path: root/src/crypto/skein.c

/***********************************************************************
**
** Implementation of the Skein hash function.
**
** Source code author: Doug Whiting, 2008.
**
** This algorithm and source code is released to the public domain.
** 
************************************************************************/

#define  SKEIN_PORT_CODE /* instantiate any code in skein_port.h */

#include <stddef.h>                          /* get size_t definition */
#include <string.h>      /* get the memcpy/memset functions */
#include "skein.h"       /* get the Skein API definitions   */

#define DISABLE_UNUSED 0

#ifndef SKEIN_256_NIST_MAX_HASHBITS
#define SKEIN_256_NIST_MAX_HASHBITS (0)
#endif

#ifndef SKEIN_512_NIST_MAX_HASHBITS
#define SKEIN_512_NIST_MAX_HASHBITS (512)
#endif

#define  SKEIN_MODIFIER_WORDS  ( 2)          /* number of modifier (tweak) words */

#define  SKEIN_256_STATE_WORDS ( 4)
#define  SKEIN_512_STATE_WORDS ( 8)
#define  SKEIN1024_STATE_WORDS (16)
#define  SKEIN_MAX_STATE_WORDS (16)

#define  SKEIN_256_STATE_BYTES ( 8*SKEIN_256_STATE_WORDS)
#define  SKEIN_512_STATE_BYTES ( 8*SKEIN_512_STATE_WORDS)
#define  SKEIN1024_STATE_BYTES ( 8*SKEIN1024_STATE_WORDS)

#define  SKEIN_256_STATE_BITS  (64*SKEIN_256_STATE_WORDS)
#define  SKEIN_512_STATE_BITS  (64*SKEIN_512_STATE_WORDS)
#define  SKEIN1024_STATE_BITS  (64*SKEIN1024_STATE_WORDS)

#define  SKEIN_256_BLOCK_BYTES ( 8*SKEIN_256_STATE_WORDS)
#define  SKEIN_512_BLOCK_BYTES ( 8*SKEIN_512_STATE_WORDS)
#define  SKEIN1024_BLOCK_BYTES ( 8*SKEIN1024_STATE_WORDS)

#define SKEIN_RND_SPECIAL       (1000u)
#define SKEIN_RND_KEY_INITIAL   (SKEIN_RND_SPECIAL+0u)
#define SKEIN_RND_KEY_INJECT    (SKEIN_RND_SPECIAL+1u)
#define SKEIN_RND_FEED_FWD      (SKEIN_RND_SPECIAL+2u)

typedef struct
{
  size_t  hashBitLen;                      /* size of hash result, in bits */
  size_t  bCnt;                            /* current byte count in buffer b[] */
  u64b_t  T[SKEIN_MODIFIER_WORDS];         /* tweak words: T[0]=byte cnt, T[1]=flags */
} Skein_Ctxt_Hdr_t;

typedef struct                               /*  256-bit Skein hash context structure */
{
  Skein_Ctxt_Hdr_t h;                      /* common header context variables */
  u64b_t  X[SKEIN_256_STATE_WORDS];        /* chaining variables */
  u08b_t  b[SKEIN_256_BLOCK_BYTES];        /* partial block buffer (8-byte aligned) */
} Skein_256_Ctxt_t;

typedef struct                               /*  512-bit Skein hash context structure */
{
  Skein_Ctxt_Hdr_t h;                      /* common header context variables */
  u64b_t  X[SKEIN_512_STATE_WORDS];        /* chaining variables */
  u08b_t  b[SKEIN_512_BLOCK_BYTES];        /* partial block buffer (8-byte aligned) */
} Skein_512_Ctxt_t;

typedef struct                               /* 1024-bit Skein hash context structure */
{
  Skein_Ctxt_Hdr_t h;                      /* common header context variables */
  u64b_t  X[SKEIN1024_STATE_WORDS];        /* chaining variables */
  u08b_t  b[SKEIN1024_BLOCK_BYTES];        /* partial block buffer (8-byte aligned) */
} Skein1024_Ctxt_t;

/*   Skein APIs for (incremental) "straight hashing" */
#if SKEIN_256_NIST_MAX_HASH_BITS
static int  Skein_256_Init  (Skein_256_Ctxt_t *ctx, size_t hashBitLen);
#endif
static int  Skein_512_Init  (Skein_512_Ctxt_t *ctx, size_t hashBitLen);
static int  Skein1024_Init  (Skein1024_Ctxt_t *ctx, size_t hashBitLen);

static int  Skein_256_Update(Skein_256_Ctxt_t *ctx, const u08b_t *msg, size_t msgByteCnt);
static int  Skein_512_Update(Skein_512_Ctxt_t *ctx, const u08b_t *msg, size_t msgByteCnt);
static int  Skein1024_Update(Skein1024_Ctxt_t *ctx, const u08b_t *msg, size_t msgByteCnt);

static int  Skein_256_Final (Skein_256_Ctxt_t *ctx, u08b_t * hashVal);
static int  Skein_512_Final (Skein_512_Ctxt_t *ctx, u08b_t * hashVal);
static int  Skein1024_Final (Skein1024_Ctxt_t *ctx, u08b_t * hashVal);

/*
**   Skein APIs for "extended" initialization: MAC keys, tree hashing.
**   After an InitExt() call, just use Update/Final calls as with Init().
**
**   Notes: Same parameters as _Init() calls, plus treeInfo/key/keyBytes.
**          When keyBytes == 0 and treeInfo == SKEIN_SEQUENTIAL, 
**              the results of InitExt() are identical to calling Init().
**          The function Init() may be called once to "precompute" the IV for
**              a given hashBitLen value, then by saving a copy of the context
**              the IV computation may be avoided in later calls.
**          Similarly, the function InitExt() may be called once per MAC key 
**              to precompute the MAC IV, then a copy of the context saved and
**              reused for each new MAC computation.
**/
#if 0
static int  Skein_256_InitExt(Skein_256_Ctxt_t *ctx, size_t hashBitLen, u64b_t treeInfo, const u08b_t *key, size_t keyBytes);
static int  Skein_512_InitExt(Skein_512_Ctxt_t *ctx, size_t hashBitLen, u64b_t treeInfo, const u08b_t *key, size_t keyBytes);
static int  Skein1024_InitExt(Skein1024_Ctxt_t *ctx, size_t hashBitLen, u64b_t treeInfo, const u08b_t *key, size_t keyBytes);
#endif

/*
**   Skein APIs for MAC and tree hash:
**      Final_Pad:  pad, do final block, but no OUTPUT type
**      Output:     do just the output stage
*/
#if 0
static int  Skein_256_Final_Pad(Skein_256_Ctxt_t *ctx, u08b_t * hashVal);
static int  Skein_512_Final_Pad(Skein_512_Ctxt_t *ctx, u08b_t * hashVal);
static int  Skein1024_Final_Pad(Skein1024_Ctxt_t *ctx, u08b_t * hashVal);
#endif

#ifndef SKEIN_TREE_HASH
#define SKEIN_TREE_HASH (1)
#endif
#if 0
#if  SKEIN_TREE_HASH
static int  Skein_256_Output   (Skein_256_Ctxt_t *ctx, u08b_t * hashVal);
static int  Skein_512_Output   (Skein_512_Ctxt_t *ctx, u08b_t * hashVal);
static int  Skein1024_Output   (Skein1024_Ctxt_t *ctx, u08b_t * hashVal);
#endif
#endif

/*****************************************************************
** "Internal" Skein definitions
**    -- not needed for sequential hashing API, but will be 
**           helpful for other uses of Skein (e.g., tree hash mode).
**    -- included here so that they can be shared between
**           reference and optimized code.
******************************************************************/

/* tweak word T[1]: bit field starting positions */
#define SKEIN_T1_BIT(BIT)       ((BIT) - 64)            /* offset 64 because it's the second word  */

#define SKEIN_T1_POS_TREE_LVL   SKEIN_T1_BIT(112)       /* bits 112..118: level in hash tree       */
#define SKEIN_T1_POS_BIT_PAD    SKEIN_T1_BIT(119)       /* bit  119     : partial final input byte */
#define SKEIN_T1_POS_BLK_TYPE   SKEIN_T1_BIT(120)       /* bits 120..125: type field               */
#define SKEIN_T1_POS_FIRST      SKEIN_T1_BIT(126)       /* bits 126     : first block flag         */
#define SKEIN_T1_POS_FINAL      SKEIN_T1_BIT(127)       /* bit  127     : final block flag         */

/* tweak word T[1]: flag bit definition(s) */
#define SKEIN_T1_FLAG_FIRST     (((u64b_t)  1 ) << SKEIN_T1_POS_FIRST)
#define SKEIN_T1_FLAG_FINAL     (((u64b_t)  1 ) << SKEIN_T1_POS_FINAL)
#define SKEIN_T1_FLAG_BIT_PAD   (((u64b_t)  1 ) << SKEIN_T1_POS_BIT_PAD)

/* tweak word T[1]: tree level bit field mask */
#define SKEIN_T1_TREE_LVL_MASK  (((u64b_t)0x7F) << SKEIN_T1_POS_TREE_LVL)
#define SKEIN_T1_TREE_LEVEL(n)  (((u64b_t) (n)) << SKEIN_T1_POS_TREE_LVL)

/* tweak word T[1]: block type field */
#define SKEIN_BLK_TYPE_KEY      ( 0)                    /* key, for MAC and KDF */
#define SKEIN_BLK_TYPE_CFG      ( 4)                    /* configuration block */
#define SKEIN_BLK_TYPE_PERS     ( 8)                    /* personalization string */
#define SKEIN_BLK_TYPE_PK       (12)                    /* public key (for digital signature hashing) */
#define SKEIN_BLK_TYPE_KDF      (16)                    /* key identifier for KDF */
#define SKEIN_BLK_TYPE_NONCE    (20)                    /* nonce for PRNG */
#define SKEIN_BLK_TYPE_MSG      (48)                    /* message processing */
#define SKEIN_BLK_TYPE_OUT      (63)                    /* output stage */
#define SKEIN_BLK_TYPE_MASK     (63)                    /* bit field mask */

#define SKEIN_T1_BLK_TYPE(T)   (((u64b_t) (SKEIN_BLK_TYPE_##T)) << SKEIN_T1_POS_BLK_TYPE)
#define SKEIN_T1_BLK_TYPE_KEY   SKEIN_T1_BLK_TYPE(KEY)  /* key, for MAC and KDF */
#define SKEIN_T1_BLK_TYPE_CFG   SKEIN_T1_BLK_TYPE(CFG)  /* configuration block */
#define SKEIN_T1_BLK_TYPE_PERS  SKEIN_T1_BLK_TYPE(PERS) /* personalization string */
#define SKEIN_T1_BLK_TYPE_PK    SKEIN_T1_BLK_TYPE(PK)   /* public key (for digital signature hashing) */
#define SKEIN_T1_BLK_TYPE_KDF   SKEIN_T1_BLK_TYPE(KDF)  /* key identifier for KDF */
#define SKEIN_T1_BLK_TYPE_NONCE SKEIN_T1_BLK_TYPE(NONCE)/* nonce for PRNG */
#define SKEIN_T1_BLK_TYPE_MSG   SKEIN_T1_BLK_TYPE(MSG)  /* message processing */
#define SKEIN_T1_BLK_TYPE_OUT   SKEIN_T1_BLK_TYPE(OUT)  /* output stage */
#define SKEIN_T1_BLK_TYPE_MASK  SKEIN_T1_BLK_TYPE(MASK) /* field bit mask */

#define SKEIN_T1_BLK_TYPE_CFG_FINAL       (SKEIN_T1_BLK_TYPE_CFG | SKEIN_T1_FLAG_FINAL)
#define SKEIN_T1_BLK_TYPE_OUT_FINAL       (SKEIN_T1_BLK_TYPE_OUT | SKEIN_T1_FLAG_FINAL)

#define SKEIN_VERSION           (1)

#ifndef SKEIN_ID_STRING_LE      /* allow compile-time personalization */
#define SKEIN_ID_STRING_LE      (0x33414853)            /* "SHA3" (little-endian)*/
#endif

#define SKEIN_MK_64(hi32,lo32)  ((lo32) + (((u64b_t) (hi32)) << 32))
#define SKEIN_SCHEMA_VER        SKEIN_MK_64(SKEIN_VERSION,SKEIN_ID_STRING_LE)
#define SKEIN_KS_PARITY         SKEIN_MK_64(0x1BD11BDA,0xA9FC1A22)

#define SKEIN_CFG_STR_LEN       (4*8)

/* bit field definitions in config block treeInfo word */
#define SKEIN_CFG_TREE_LEAF_SIZE_POS  ( 0)
#define SKEIN_CFG_TREE_NODE_SIZE_POS  ( 8)
#define SKEIN_CFG_TREE_MAX_LEVEL_POS  (16)

#define SKEIN_CFG_TREE_LEAF_SIZE_MSK  (((u64b_t) 0xFF) << SKEIN_CFG_TREE_LEAF_SIZE_POS)
#define SKEIN_CFG_TREE_NODE_SIZE_MSK  (((u64b_t) 0xFF) << SKEIN_CFG_TREE_NODE_SIZE_POS)
#define SKEIN_CFG_TREE_MAX_LEVEL_MSK  (((u64b_t) 0xFF) << SKEIN_CFG_TREE_MAX_LEVEL_POS)

#define SKEIN_CFG_TREE_INFO(leaf,node,maxLvl)                   \
  ( (((u64b_t)(leaf  )) << SKEIN_CFG_TREE_LEAF_SIZE_POS) |    \
  (((u64b_t)(node  )) << SKEIN_CFG_TREE_NODE_SIZE_POS) |    \
  (((u64b_t)(maxLvl)) << SKEIN_CFG_TREE_MAX_LEVEL_POS) )

#define SKEIN_CFG_TREE_INFO_SEQUENTIAL SKEIN_CFG_TREE_INFO(0,0,0) /* use as treeInfo in InitExt() call for sequential processing */

/*
**   Skein macros for getting/setting tweak words, etc.
**   These are useful for partial input bytes, hash tree init/update, etc.
**/
#define Skein_Get_Tweak(ctxPtr,TWK_NUM)         ((ctxPtr)->h.T[TWK_NUM])
#define Skein_Set_Tweak(ctxPtr,TWK_NUM,tVal)    {(ctxPtr)->h.T[TWK_NUM] = (tVal);}

#define Skein_Get_T0(ctxPtr)    Skein_Get_Tweak(ctxPtr,0)
#define Skein_Get_T1(ctxPtr)    Skein_Get_Tweak(ctxPtr,1)
#define Skein_Set_T0(ctxPtr,T0) Skein_Set_Tweak(ctxPtr,0,T0)
#define Skein_Set_T1(ctxPtr,T1) Skein_Set_Tweak(ctxPtr,1,T1)

/* set both tweak words at once */
#define Skein_Set_T0_T1(ctxPtr,T0,T1)           \
{                                           \
  Skein_Set_T0(ctxPtr,(T0));                  \
  Skein_Set_T1(ctxPtr,(T1));                  \
}

#define Skein_Set_Type(ctxPtr,BLK_TYPE)         \
  Skein_Set_T1(ctxPtr,SKEIN_T1_BLK_TYPE_##BLK_TYPE)

/* set up for starting with a new type: h.T[0]=0; h.T[1] = NEW_TYPE; h.bCnt=0; */
#define Skein_Start_New_Type(ctxPtr,BLK_TYPE)   \
{ Skein_Set_T0_T1(ctxPtr,0,SKEIN_T1_FLAG_FIRST | SKEIN_T1_BLK_TYPE_##BLK_TYPE); (ctxPtr)->h.bCnt=0; }

#define Skein_Clear_First_Flag(hdr)      { (hdr).T[1] &= ~SKEIN_T1_FLAG_FIRST;       }
#define Skein_Set_Bit_Pad_Flag(hdr)      { (hdr).T[1] |=  SKEIN_T1_FLAG_BIT_PAD;     }

#define Skein_Set_Tree_Level(hdr,height) { (hdr).T[1] |= SKEIN_T1_TREE_LEVEL(height);}

/*****************************************************************
** "Internal" Skein definitions for debugging and error checking
******************************************************************/
#define Skein_Show_Block(bits,ctx,X,blkPtr,wPtr,ksEvenPtr,ksOddPtr)
#define Skein_Show_Round(bits,ctx,r,X)
#define Skein_Show_R_Ptr(bits,ctx,r,X_ptr)
#define Skein_Show_Final(bits,ctx,cnt,outPtr)
#define Skein_Show_Key(bits,ctx,key,keyBytes)


#ifndef SKEIN_ERR_CHECK        /* run-time checks (e.g., bad params, uninitialized context)? */
#define Skein_Assert(x,retCode)/* default: ignore all Asserts, for performance */
#define Skein_assert(x)
#elif   defined(SKEIN_ASSERT)
#include <assert.h>     
#define Skein_Assert(x,retCode) assert(x) 
#define Skein_assert(x)         assert(x) 
#else
#include <assert.h>     
#define Skein_Assert(x,retCode) { if (!(x)) return retCode; } /*  caller  error */
#define Skein_assert(x)         assert(x)                     /* internal error */
#endif

/*****************************************************************
** Skein block function constants (shared across Ref and Opt code)
******************************************************************/
enum    
{   
  /* Skein_256 round rotation constants */
  R_256_0_0=14, R_256_0_1=16,
  R_256_1_0=52, R_256_1_1=57,
  R_256_2_0=23, R_256_2_1=40,
  R_256_3_0= 5, R_256_3_1=37,
  R_256_4_0=25, R_256_4_1=33,
  R_256_5_0=46, R_256_5_1=12,
  R_256_6_0=58, R_256_6_1=22,
  R_256_7_0=32, R_256_7_1=32,

  /* Skein_512 round rotation constants */
  R_512_0_0=46, R_512_0_1=36, R_512_0_2=19, R_512_0_3=37,
  R_512_1_0=33, R_512_1_1=27, R_512_1_2=14, R_512_1_3=42,
  R_512_2_0=17, R_512_2_1=49, R_512_2_2=36, R_512_2_3=39,
  R_512_3_0=44, R_512_3_1= 9, R_512_3_2=54, R_512_3_3=56,
  R_512_4_0=39, R_512_4_1=30, R_512_4_2=34, R_512_4_3=24,
  R_512_5_0=13, R_512_5_1=50, R_512_5_2=10, R_512_5_3=17,
  R_512_6_0=25, R_512_6_1=29, R_512_6_2=39, R_512_6_3=43,
  R_512_7_0= 8, R_512_7_1=35, R_512_7_2=56, R_512_7_3=22,

  /* Skein1024 round rotation constants */
  R1024_0_0=24, R1024_0_1=13, R1024_0_2= 8, R1024_0_3=47, R1024_0_4= 8, R1024_0_5=17, R1024_0_6=22, R1024_0_7=37,
  R1024_1_0=38, R1024_1_1=19, R1024_1_2=10, R1024_1_3=55, R1024_1_4=49, R1024_1_5=18, R1024_1_6=23, R1024_1_7=52,
  R1024_2_0=33, R1024_2_1= 4, R1024_2_2=51, R1024_2_3=13, R1024_2_4=34, R1024_2_5=41, R1024_2_6=59, R1024_2_7=17,
  R1024_3_0= 5, R1024_3_1=20, R1024_3_2=48, R1024_3_3=41, R1024_3_4=47, R1024_3_5=28, R1024_3_6=16, R1024_3_7=25,
  R1024_4_0=41, R1024_4_1= 9, R1024_4_2=37, R1024_4_3=31, R1024_4_4=12, R1024_4_5=47, R1024_4_6=44, R1024_4_7=30,
  R1024_5_0=16, R1024_5_1=34, R1024_5_2=56, R1024_5_3=51, R1024_5_4= 4, R1024_5_5=53, R1024_5_6=42, R1024_5_7=41,
  R1024_6_0=31, R1024_6_1=44, R1024_6_2=47, R1024_6_3=46, R1024_6_4=19, R1024_6_5=42, R1024_6_6=44, R1024_6_7=25,
  R1024_7_0= 9, R1024_7_1=48, R1024_7_2=35, R1024_7_3=52, R1024_7_4=23, R1024_7_5=31, R1024_7_6=37, R1024_7_7=20
};

#ifndef SKEIN_ROUNDS
#define SKEIN_256_ROUNDS_TOTAL (72)          /* number of rounds for the different block sizes */
#define SKEIN_512_ROUNDS_TOTAL (72)
#define SKEIN1024_ROUNDS_TOTAL (80)
#else                                        /* allow command-line define in range 8*(5..14)   */
#define SKEIN_256_ROUNDS_TOTAL (8*((((SKEIN_ROUNDS/100) + 5) % 10) + 5))
#define SKEIN_512_ROUNDS_TOTAL (8*((((SKEIN_ROUNDS/ 10) + 5) % 10) + 5))
#define SKEIN1024_ROUNDS_TOTAL (8*((((SKEIN_ROUNDS    ) + 5) % 10) + 5))
#endif


/*
***************** Pre-computed Skein IVs *******************
**
** NOTE: these values are not "magic" constants, but
** are generated using the Threefish block function.
** They are pre-computed here only for speed; i.e., to
** avoid the need for a Threefish call during Init().
**
** The IV for any fixed hash length may be pre-computed.
** Only the most common values are included here.
**
************************************************************
**/

#define MK_64 SKEIN_MK_64

/* blkSize =  256 bits. hashSize =  128 bits */
const u64b_t SKEIN_256_IV_128[] =
    {
    MK_64(0xE1111906,0x964D7260),
    MK_64(0x883DAAA7,0x7C8D811C),
    MK_64(0x10080DF4,0x91960F7A),
    MK_64(0xCCF7DDE5,0xB45BC1C2)
    };

/* blkSize =  256 bits. hashSize =  160 bits */
const u64b_t SKEIN_256_IV_160[] =
    {
    MK_64(0x14202314,0x72825E98),
    MK_64(0x2AC4E9A2,0x5A77E590),
    MK_64(0xD47A5856,0x8838D63E),
    MK_64(0x2DD2E496,0x8586AB7D)
    };

/* blkSize =  256 bits. hashSize =  224 bits */
const u64b_t SKEIN_256_IV_224[] =
    {
    MK_64(0xC6098A8C,0x9AE5EA0B),
    MK_64(0x876D5686,0x08C5191C),
    MK_64(0x99CB88D7,0xD7F53884),
    MK_64(0x384BDDB1,0xAEDDB5DE)
    };

/* blkSize =  256 bits. hashSize =  256 bits */
const u64b_t SKEIN_256_IV_256[] =
    {
    MK_64(0xFC9DA860,0xD048B449),
    MK_64(0x2FCA6647,0x9FA7D833),
    MK_64(0xB33BC389,0x6656840F),
    MK_64(0x6A54E920,0xFDE8DA69)
    };

/* blkSize =  512 bits. hashSize =  128 bits */
const u64b_t SKEIN_512_IV_128[] =
    {
    MK_64(0xA8BC7BF3,0x6FBF9F52),
    MK_64(0x1E9872CE,0xBD1AF0AA),
    MK_64(0x309B1790,0xB32190D3),
    MK_64(0xBCFBB854,0x3F94805C),
    MK_64(0x0DA61BCD,0x6E31B11B),
    MK_64(0x1A18EBEA,0xD46A32E3),
    MK_64(0xA2CC5B18,0xCE84AA82),
    MK_64(0x6982AB28,0x9D46982D)
    };

/* blkSize =  512 bits. hashSize =  160 bits */
const u64b_t SKEIN_512_IV_160[] =
    {
    MK_64(0x28B81A2A,0xE013BD91),
    MK_64(0xC2F11668,0xB5BDF78F),
    MK_64(0x1760D8F3,0xF6A56F12),
    MK_64(0x4FB74758,0x8239904F),
    MK_64(0x21EDE07F,0x7EAF5056),
    MK_64(0xD908922E,0x63ED70B8),
    MK_64(0xB8EC76FF,0xECCB52FA),
    MK_64(0x01A47BB8,0xA3F27A6E)
    };

/* blkSize =  512 bits. hashSize =  224 bits */
const u64b_t SKEIN_512_IV_224[] =
    {
    MK_64(0xCCD06162,0x48677224),
    MK_64(0xCBA65CF3,0xA92339EF),
    MK_64(0x8CCD69D6,0x52FF4B64),
    MK_64(0x398AED7B,0x3AB890B4),
    MK_64(0x0F59D1B1,0x457D2BD0),
    MK_64(0x6776FE65,0x75D4EB3D),
    MK_64(0x99FBC70E,0x997413E9),
    MK_64(0x9E2CFCCF,0xE1C41EF7)
    };

/* blkSize =  512 bits. hashSize =  256 bits */
const u64b_t SKEIN_512_IV_256[] =
    {
    MK_64(0xCCD044A1,0x2FDB3E13),
    MK_64(0xE8359030,0x1A79A9EB),
    MK_64(0x55AEA061,0x4F816E6F),
    MK_64(0x2A2767A4,0xAE9B94DB),
    MK_64(0xEC06025E,0x74DD7683),
    MK_64(0xE7A436CD,0xC4746251),
    MK_64(0xC36FBAF9,0x393AD185),
    MK_64(0x3EEDBA18,0x33EDFC13)
    };

/* blkSize =  512 bits. hashSize =  384 bits */
const u64b_t SKEIN_512_IV_384[] =
    {
    MK_64(0xA3F6C6BF,0x3A75EF5F),
    MK_64(0xB0FEF9CC,0xFD84FAA4),
    MK_64(0x9D77DD66,0x3D770CFE),
    MK_64(0xD798CBF3,0xB468FDDA),
    MK_64(0x1BC4A666,0x8A0E4465),
    MK_64(0x7ED7D434,0xE5807407),
    MK_64(0x548FC1AC,0xD4EC44D6),
    MK_64(0x266E1754,0x6AA18FF8)
    };

/* blkSize =  512 bits. hashSize =  512 bits */
const u64b_t SKEIN_512_IV_512[] =
    {
    MK_64(0x4903ADFF,0x749C51CE),
    MK_64(0x0D95DE39,0x9746DF03),
    MK_64(0x8FD19341,0x27C79BCE),
    MK_64(0x9A255629,0xFF352CB1),
    MK_64(0x5DB62599,0xDF6CA7B0),
    MK_64(0xEABE394C,0xA9D5C3F4),
    MK_64(0x991112C7,0x1A75B523),
    MK_64(0xAE18A40B,0x660FCC33)
    };

/* blkSize = 1024 bits. hashSize =  384 bits */
const u64b_t SKEIN1024_IV_384[] =
    {
    MK_64(0x5102B6B8,0xC1894A35),
    MK_64(0xFEEBC9E3,0xFE8AF11A),
    MK_64(0x0C807F06,0xE32BED71),
    MK_64(0x60C13A52,0xB41A91F6),
    MK_64(0x9716D35D,0xD4917C38),
    MK_64(0xE780DF12,0x6FD31D3A),
    MK_64(0x797846B6,0xC898303A),
    MK_64(0xB172C2A8,0xB3572A3B),
    MK_64(0xC9BC8203,0xA6104A6C),
    MK_64(0x65909338,0xD75624F4),
    MK_64(0x94BCC568,0x4B3F81A0),
    MK_64(0x3EBBF51E,0x10ECFD46),
    MK_64(0x2DF50F0B,0xEEB08542),
    MK_64(0x3B5A6530,0x0DBC6516),
    MK_64(0x484B9CD2,0x167BBCE1),
    MK_64(0x2D136947,0xD4CBAFEA)
    };

/* blkSize = 1024 bits. hashSize =  512 bits */
const u64b_t SKEIN1024_IV_512[] =
    {
    MK_64(0xCAEC0E5D,0x7C1B1B18),
    MK_64(0xA01B0E04,0x5F03E802),
    MK_64(0x33840451,0xED912885),
    MK_64(0x374AFB04,0xEAEC2E1C),
    MK_64(0xDF25A0E2,0x813581F7),
    MK_64(0xE4004093,0x8B12F9D2),
    MK_64(0xA662D539,0xC2ED39B6),
    MK_64(0xFA8B85CF,0x45D8C75A),
    MK_64(0x8316ED8E,0x29EDE796),
    MK_64(0x053289C0,0x2E9F91B8),
    MK_64(0xC3F8EF1D,0x6D518B73),
    MK_64(0xBDCEC3C4,0xD5EF332E),
    MK_64(0x549A7E52,0x22974487),
    MK_64(0x67070872,0x5B749816),
    MK_64(0xB9CD28FB,0xF0581BD1),
    MK_64(0x0E2940B8,0x15804974)
    };

/* blkSize = 1024 bits. hashSize = 1024 bits */
const u64b_t SKEIN1024_IV_1024[] =
    {
    MK_64(0xD593DA07,0x41E72355),
    MK_64(0x15B5E511,0xAC73E00C),
    MK_64(0x5180E5AE,0xBAF2C4F0),
    MK_64(0x03BD41D3,0xFCBCAFAF),
    MK_64(0x1CAEC6FD,0x1983A898),
    MK_64(0x6E510B8B,0xCDD0589F),
    MK_64(0x77E2BDFD,0xC6394ADA),
    MK_64(0xC11E1DB5,0x24DCB0A3),
    MK_64(0xD6D14AF9,0xC6329AB5),
    MK_64(0x6A9B0BFC,0x6EB67E0D),
    MK_64(0x9243C60D,0xCCFF1332),
    MK_64(0x1A1F1DDE,0x743F02D4),
    MK_64(0x0996753C,0x10ED0BB8),
    MK_64(0x6572DD22,0xF2B4969A),
    MK_64(0x61FD3062,0xD00A579A),
    MK_64(0x1DE0536E,0x8682E539)
    };


#ifndef SKEIN_USE_ASM
#define SKEIN_USE_ASM   (0)                     /* default is all C code (no ASM) */
#endif

#ifndef SKEIN_LOOP
#define SKEIN_LOOP 001                          /* default: unroll 256 and 512, but not 1024 */
#endif

#define BLK_BITS        (WCNT*64)               /* some useful definitions for code here */
#define KW_TWK_BASE     (0)
#define KW_KEY_BASE     (3)
#define ks              (kw + KW_KEY_BASE)                
#define ts              (kw + KW_TWK_BASE)

#ifdef SKEIN_DEBUG
#define DebugSaveTweak(ctx) { ctx->h.T[0] = ts[0]; ctx->h.T[1] = ts[1]; }
#else
#define DebugSaveTweak(ctx)
#endif

/*****************************  Skein_256 ******************************/
#if !(SKEIN_USE_ASM & 256)
static void Skein_256_Process_Block(Skein_256_Ctxt_t *ctx,const u08b_t *blkPtr,size_t blkCnt,size_t byteCntAdd)
    { /* do it in C */
    enum
        {
        WCNT = SKEIN_256_STATE_WORDS
        };
#undef  RCNT
#define RCNT  (SKEIN_256_ROUNDS_TOTAL/8)

#ifdef  SKEIN_LOOP                              /* configure how much to unroll the loop */
#define SKEIN_UNROLL_256 (((SKEIN_LOOP)/100)%10)
#else
#define SKEIN_UNROLL_256 (0)
#endif

#if SKEIN_UNROLL_256
#if (RCNT % SKEIN_UNROLL_256)
#error "Invalid SKEIN_UNROLL_256"               /* sanity check on unroll count */
#endif
    size_t  r;
    u64b_t  kw[WCNT+4+RCNT*2];                  /* key schedule words : chaining vars + tweak + "rotation"*/
#else
    u64b_t  kw[WCNT+4];                         /* key schedule words : chaining vars + tweak */
#endif
    u64b_t  X0,X1,X2,X3;                        /* local copy of context vars, for speed */
    u64b_t  w [WCNT];                           /* local copy of input block */
#ifdef SKEIN_DEBUG
    const u64b_t *Xptr[4];                      /* use for debugging (help compiler put Xn in registers) */
    Xptr[0] = &X0;  Xptr[1] = &X1;  Xptr[2] = &X2;  Xptr[3] = &X3;
#endif
    Skein_assert(blkCnt != 0);                  /* never call with blkCnt == 0! */
    ts[0] = ctx->h.T[0];
    ts[1] = ctx->h.T[1];
    do  {
        /* this implementation only supports 2**64 input bytes (no carry out here) */
        ts[0] += byteCntAdd;                    /* update processed length */

        /* precompute the key schedule for this block */
        ks[0] = ctx->X[0];     
        ks[1] = ctx->X[1];
        ks[2] = ctx->X[2];
        ks[3] = ctx->X[3];
        ks[4] = ks[0] ^ ks[1] ^ ks[2] ^ ks[3] ^ SKEIN_KS_PARITY;

        ts[2] = ts[0] ^ ts[1];

        Skein_Get64_LSB_First(w,blkPtr,WCNT);   /* get input block in little-endian format */
        DebugSaveTweak(ctx);
        Skein_Show_Block(BLK_BITS,&ctx->h,ctx->X,blkPtr,w,ks,ts);

        X0 = w[0] + ks[0];                      /* do the first full key injection */
        X1 = w[1] + ks[1] + ts[0];
        X2 = w[2] + ks[2] + ts[1];
        X3 = w[3] + ks[3];

        Skein_Show_R_Ptr(BLK_BITS,&ctx->h,SKEIN_RND_KEY_INITIAL,Xptr);    /* show starting state values */

        blkPtr += SKEIN_256_BLOCK_BYTES;

        /* run the rounds */

#define Round256(p0,p1,p2,p3,ROT,rNum)                              \
    X##p0 += X##p1; X##p1 = RotL_64(X##p1,ROT##_0); X##p1 ^= X##p0; \
    X##p2 += X##p3; X##p3 = RotL_64(X##p3,ROT##_1); X##p3 ^= X##p2; \

#if SKEIN_UNROLL_256 == 0                       
#define R256(p0,p1,p2,p3,ROT,rNum)           /* fully unrolled */   \
    Round256(p0,p1,p2,p3,ROT,rNum)                                  \
    Skein_Show_R_Ptr(BLK_BITS,&ctx->h,rNum,Xptr);

#define I256(R)                                                     \
    X0   += ks[((R)+1) % 5];    /* inject the key schedule value */ \
    X1   += ks[((R)+2) % 5] + ts[((R)+1) % 3];                      \
    X2   += ks[((R)+3) % 5] + ts[((R)+2) % 3];                      \
    X3   += ks[((R)+4) % 5] +     (R)+1;                            \
    Skein_Show_R_Ptr(BLK_BITS,&ctx->h,SKEIN_RND_KEY_INJECT,Xptr);
#else                                       /* looping version */
#define R256(p0,p1,p2,p3,ROT,rNum)                                  \
    Round256(p0,p1,p2,p3,ROT,rNum)                                  \
    Skein_Show_R_Ptr(BLK_BITS,&ctx->h,4*(r-1)+rNum,Xptr);

#define I256(R)                                                     \
    X0   += ks[r+(R)+0];        /* inject the key schedule value */ \
    X1   += ks[r+(R)+1] + ts[r+(R)+0];                              \
    X2   += ks[r+(R)+2] + ts[r+(R)+1];                              \
    X3   += ks[r+(R)+3] +    r+(R)   ;                              \
    ks[r + (R)+4    ]   = ks[r+(R)-1];     /* rotate key schedule */\
    ts[r + (R)+2    ]   = ts[r+(R)-1];                              \
    Skein_Show_R_Ptr(BLK_BITS,&ctx->h,SKEIN_RND_KEY_INJECT,Xptr);

    for (r=1;r < 2*RCNT;r+=2*SKEIN_UNROLL_256)  /* loop thru it */
#endif  
        {    
#define R256_8_rounds(R)                  \
        R256(0,1,2,3,R_256_0,8*(R) + 1);  \
        R256(0,3,2,1,R_256_1,8*(R) + 2);  \
        R256(0,1,2,3,R_256_2,8*(R) + 3);  \
        R256(0,3,2,1,R_256_3,8*(R) + 4);  \
        I256(2*(R));                      \
        R256(0,1,2,3,R_256_4,8*(R) + 5);  \
        R256(0,3,2,1,R_256_5,8*(R) + 6);  \
        R256(0,1,2,3,R_256_6,8*(R) + 7);  \
        R256(0,3,2,1,R_256_7,8*(R) + 8);  \
        I256(2*(R)+1);

        R256_8_rounds( 0);

#define R256_Unroll_R(NN) ((SKEIN_UNROLL_256 == 0 && SKEIN_256_ROUNDS_TOTAL/8 > (NN)) || (SKEIN_UNROLL_256 > (NN)))

  #if   R256_Unroll_R( 1)
        R256_8_rounds( 1);
  #endif
  #if   R256_Unroll_R( 2)
        R256_8_rounds( 2);
  #endif
  #if   R256_Unroll_R( 3)
        R256_8_rounds( 3);
  #endif
  #if   R256_Unroll_R( 4)
        R256_8_rounds( 4);
  #endif
  #if   R256_Unroll_R( 5)
        R256_8_rounds( 5);
  #endif
  #if   R256_Unroll_R( 6)
        R256_8_rounds( 6);
  #endif
  #if   R256_Unroll_R( 7)
        R256_8_rounds( 7);
  #endif
  #if   R256_Unroll_R( 8)
        R256_8_rounds( 8);
  #endif
  #if   R256_Unroll_R( 9)
        R256_8_rounds( 9);
  #endif
  #if   R256_Unroll_R(10)
        R256_8_rounds(10);
  #endif
  #if   R256_Unroll_R(11)
        R256_8_rounds(11);
  #endif
  #if   R256_Unroll_R(12)
        R256_8_rounds(12);
  #endif
  #if   R256_Unroll_R(13)
        R256_8_rounds(13);
  #endif
  #if   R256_Unroll_R(14)
        R256_8_rounds(14);
  #endif
  #if  (SKEIN_UNROLL_256 > 14)
#error  "need more unrolling in Skein_256_Process_Block"
  #endif
        }
        /* do the final "feedforward" xor, update context chaining vars */
        ctx->X[0] = X0 ^ w[0];
        ctx->X[1] = X1 ^ w[1];
        ctx->X[2] = X2 ^ w[2];
        ctx->X[3] = X3 ^ w[3];

        Skein_Show_Round(BLK_BITS,&ctx->h,SKEIN_RND_FEED_FWD,ctx->X);

        ts[1] &= ~SKEIN_T1_FLAG_FIRST;
        }
    while (--blkCnt);
    ctx->h.T[0] = ts[0];
    ctx->h.T[1] = ts[1];
    }

#if defined(SKEIN_CODE_SIZE) || defined(SKEIN_PERF)
static size_t Skein_256_Process_Block_CodeSize(void)
    {
    return ((u08b_t *) Skein_256_Process_Block_CodeSize) -
           ((u08b_t *) Skein_256_Process_Block);
    }
static uint_t Skein_256_Unroll_Cnt(void)
    {
    return SKEIN_UNROLL_256;
    }
#endif
#endif

/*****************************  Skein_512 ******************************/
#if !(SKEIN_USE_ASM & 512)
static void Skein_512_Process_Block(Skein_512_Ctxt_t *ctx,const u08b_t *blkPtr,size_t blkCnt,size_t byteCntAdd)
    { /* do it in C */
    enum
        {
        WCNT = SKEIN_512_STATE_WORDS
        };
#undef  RCNT
#define RCNT  (SKEIN_512_ROUNDS_TOTAL/8)

#ifdef  SKEIN_LOOP                              /* configure how much to unroll the loop */
#define SKEIN_UNROLL_512 (((SKEIN_LOOP)/10)%10)
#else
#define SKEIN_UNROLL_512 (0)
#endif

#if SKEIN_UNROLL_512
#if (RCNT % SKEIN_UNROLL_512)
#error "Invalid SKEIN_UNROLL_512"               /* sanity check on unroll count */
#endif
    size_t  r;
    u64b_t  kw[WCNT+4+RCNT*2];                  /* key schedule words : chaining vars + tweak + "rotation"*/
#else
    u64b_t  kw[WCNT+4];                         /* key schedule words : chaining vars + tweak */
#endif
    u64b_t  X0,X1,X2,X3,X4,X5,X6,X7;            /* local copy of vars, for speed */
    u64b_t  w [WCNT];                           /* local copy of input block */
#ifdef SKEIN_DEBUG
    const u64b_t *Xptr[8];                      /* use for debugging (help compiler put Xn in registers) */
    Xptr[0] = &X0;  Xptr[1] = &X1;  Xptr[2] = &X2;  Xptr[3] = &X3;
    Xptr[4] = &X4;  Xptr[5] = &X5;  Xptr[6] = &X6;  Xptr[7] = &X7;
#endif

    Skein_assert(blkCnt != 0);                  /* never call with blkCnt == 0! */
    ts[0] = ctx->h.T[0];
    ts[1] = ctx->h.T[1];
    do  {
        /* this implementation only supports 2**64 input bytes (no carry out here) */
        ts[0] += byteCntAdd;                    /* update processed length */

        /* precompute the key schedule for this block */
        ks[0] = ctx->X[0];
        ks[1] = ctx->X[1];
        ks[2] = ctx->X[2];
        ks[3] = ctx->X[3];
        ks[4] = ctx->X[4];
        ks[5] = ctx->X[5];
        ks[6] = ctx->X[6];
        ks[7] = ctx->X[7];
        ks[8] = ks[0] ^ ks[1] ^ ks[2] ^ ks[3] ^ 
                ks[4] ^ ks[5] ^ ks[6] ^ ks[7] ^ SKEIN_KS_PARITY;

        ts[2] = ts[0] ^ ts[1];

        Skein_Get64_LSB_First(w,blkPtr,WCNT); /* get input block in little-endian format */
        DebugSaveTweak(ctx);
        Skein_Show_Block(BLK_BITS,&ctx->h,ctx->X,blkPtr,w,ks,ts);

        X0   = w[0] + ks[0];                    /* do the first full key injection */
        X1   = w[1] + ks[1];
        X2   = w[2] + ks[2];
        X3   = w[3] + ks[3];
        X4   = w[4] + ks[4];
        X5   = w[5] + ks[5] + ts[0];
        X6   = w[6] + ks[6] + ts[1];
        X7   = w[7] + ks[7];

        blkPtr += SKEIN_512_BLOCK_BYTES;

        Skein_Show_R_Ptr(BLK_BITS,&ctx->h,SKEIN_RND_KEY_INITIAL,Xptr);
        /* run the rounds */
#define Round512(p0,p1,p2,p3,p4,p5,p6,p7,ROT,rNum)                  \
    X##p0 += X##p1; X##p1 = RotL_64(X##p1,ROT##_0); X##p1 ^= X##p0; \
    X##p2 += X##p3; X##p3 = RotL_64(X##p3,ROT##_1); X##p3 ^= X##p2; \
    X##p4 += X##p5; X##p5 = RotL_64(X##p5,ROT##_2); X##p5 ^= X##p4; \
    X##p6 += X##p7; X##p7 = RotL_64(X##p7,ROT##_3); X##p7 ^= X##p6; \

#if SKEIN_UNROLL_512 == 0                       
#define R512(p0,p1,p2,p3,p4,p5,p6,p7,ROT,rNum)      /* unrolled */  \
    Round512(p0,p1,p2,p3,p4,p5,p6,p7,ROT,rNum)                      \
    Skein_Show_R_Ptr(BLK_BITS,&ctx->h,rNum,Xptr);

#define I512(R)                                                     \
    X0   += ks[((R)+1) % 9];   /* inject the key schedule value */  \
    X1   += ks[((R)+2) % 9];                                        \
    X2   += ks[((R)+3) % 9];                                        \
    X3   += ks[((R)+4) % 9];                                        \
    X4   += ks[((R)+5) % 9];                                        \
    X5   += ks[((R)+6) % 9] + ts[((R)+1) % 3];                      \
    X6   += ks[((R)+7) % 9] + ts[((R)+2) % 3];                      \
    X7   += ks[((R)+8) % 9] +     (R)+1;                            \
    Skein_Show_R_Ptr(BLK_BITS,&ctx->h,SKEIN_RND_KEY_INJECT,Xptr);
#else                                       /* looping version */
#define R512(p0,p1,p2,p3,p4,p5,p6,p7,ROT,rNum)                      \
    Round512(p0,p1,p2,p3,p4,p5,p6,p7,ROT,rNum)                      \
    Skein_Show_R_Ptr(BLK_BITS,&ctx->h,4*(r-1)+rNum,Xptr);

#define I512(R)                                                     \
    X0   += ks[r+(R)+0];        /* inject the key schedule value */ \
    X1   += ks[r+(R)+1];                                            \
    X2   += ks[r+(R)+2];                                            \
    X3   += ks[r+(R)+3];                                            \
    X4   += ks[r+(R)+4];                                            \
    X5   += ks[r+(R)+5] + ts[r+(R)+0];                              \
    X6   += ks[r+(R)+6] + ts[r+(R)+1];                              \
    X7   += ks[r+(R)+7] +    r+(R)   ;                              \
    ks[r +       (R)+8] = ks[r+(R)-1];  /* rotate key schedule */   \
    ts[r +       (R)+2] = ts[r+(R)-1];                              \
    Skein_Show_R_Ptr(BLK_BITS,&ctx->h,SKEIN_RND_KEY_INJECT,Xptr);

    for (r=1;r < 2*RCNT;r+=2*SKEIN_UNROLL_512)   /* loop thru it */
#endif                         /* end of looped code definitions */
        {
#define R512_8_rounds(R)  /* do 8 full rounds */  \
        R512(0,1,2,3,4,5,6,7,R_512_0,8*(R)+ 1);   \
        R512(2,1,4,7,6,5,0,3,R_512_1,8*(R)+ 2);   \
        R512(4,1,6,3,0,5,2,7,R_512_2,8*(R)+ 3);   \
        R512(6,1,0,7,2,5,4,3,R_512_3,8*(R)+ 4);   \
        I512(2*(R));                              \
        R512(0,1,2,3,4,5,6,7,R_512_4,8*(R)+ 5);   \
        R512(2,1,4,7,6,5,0,3,R_512_5,8*(R)+ 6);   \
        R512(4,1,6,3,0,5,2,7,R_512_6,8*(R)+ 7);   \
        R512(6,1,0,7,2,5,4,3,R_512_7,8*(R)+ 8);   \
        I512(2*(R)+1);        /* and key injection */

        R512_8_rounds( 0);

#define R512_Unroll_R(NN) ((SKEIN_UNROLL_512 == 0 && SKEIN_512_ROUNDS_TOTAL/8 > (NN)) || (SKEIN_UNROLL_512 > (NN)))

  #if   R512_Unroll_R( 1)
        R512_8_rounds( 1);
  #endif
  #if   R512_Unroll_R( 2)
        R512_8_rounds( 2);
  #endif
  #if   R512_Unroll_R( 3)
        R512_8_rounds( 3);
  #endif
  #if   R512_Unroll_R( 4)
        R512_8_rounds( 4);
  #endif
  #if   R512_Unroll_R( 5)
        R512_8_rounds( 5);
  #endif
  #if   R512_Unroll_R( 6)
        R512_8_rounds( 6);
  #endif
  #if   R512_Unroll_R( 7)
        R512_8_rounds( 7);
  #endif
  #if   R512_Unroll_R( 8)
        R512_8_rounds( 8);
  #endif
  #if   R512_Unroll_R( 9)
        R512_8_rounds( 9);
  #endif
  #if   R512_Unroll_R(10)
        R512_8_rounds(10);
  #endif
  #if   R512_Unroll_R(11)
        R512_8_rounds(11);
  #endif
  #if   R512_Unroll_R(12)
        R512_8_rounds(12);
  #endif
  #if   R512_Unroll_R(13)
        R512_8_rounds(13);
  #endif
  #if   R512_Unroll_R(14)
        R512_8_rounds(14);
  #endif
  #if  (SKEIN_UNROLL_512 > 14)
#error  "need more unrolling in Skein_512_Process_Block"
  #endif
        }

        /* do the final "feedforward" xor, update context chaining vars */
        ctx->X[0] = X0 ^ w[0];
        ctx->X[1] = X1 ^ w[1];
        ctx->X[2] = X2 ^ w[2];
        ctx->X[3] = X3 ^ w[3];
        ctx->X[4] = X4 ^ w[4];
        ctx->X[5] = X5 ^ w[5];
        ctx->X[6] = X6 ^ w[6];
        ctx->X[7] = X7 ^ w[7];
        Skein_Show_Round(BLK_BITS,&ctx->h,SKEIN_RND_FEED_FWD,ctx->X);

        ts[1] &= ~SKEIN_T1_FLAG_FIRST;
        }
    while (--blkCnt);
    ctx->h.T[0] = ts[0];
    ctx->h.T[1] = ts[1];
    }

#if defined(SKEIN_CODE_SIZE) || defined(SKEIN_PERF)
static size_t Skein_512_Process_Block_CodeSize(void)
    {
    return ((u08b_t *) Skein_512_Process_Block_CodeSize) -
           ((u08b_t *) Skein_512_Process_Block);
    }
static uint_t Skein_512_Unroll_Cnt(void)
    {
    return SKEIN_UNROLL_512;
    }
#endif
#endif

/*****************************  Skein1024 ******************************/
#if !(SKEIN_USE_ASM & 1024)
static void Skein1024_Process_Block(Skein1024_Ctxt_t *ctx,const u08b_t *blkPtr,size_t blkCnt,size_t byteCntAdd)
    { /* do it in C, always looping (unrolled is bigger AND slower!) */
    enum
        {
        WCNT = SKEIN1024_STATE_WORDS
        };
#undef  RCNT
#define RCNT  (SKEIN1024_ROUNDS_TOTAL/8)

#ifdef  SKEIN_LOOP                              /* configure how much to unroll the loop */
#define SKEIN_UNROLL_1024 ((SKEIN_LOOP)%10)
#else
#define SKEIN_UNROLL_1024 (0)
#endif

#if (SKEIN_UNROLL_1024 != 0)
#if (RCNT % SKEIN_UNROLL_1024)
#error "Invalid SKEIN_UNROLL_1024"              /* sanity check on unroll count */
#endif
    size_t  r;
    u64b_t  kw[WCNT+4+RCNT*2];                  /* key schedule words : chaining vars + tweak + "rotation"*/
#else
    u64b_t  kw[WCNT+4];                         /* key schedule words : chaining vars + tweak */
#endif

    u64b_t  X00,X01,X02,X03,X04,X05,X06,X07,    /* local copy of vars, for speed */
            X08,X09,X10,X11,X12,X13,X14,X15;
    u64b_t  w [WCNT];                           /* local copy of input block */
#ifdef SKEIN_DEBUG
    const u64b_t *Xptr[16];                     /* use for debugging (help compiler put Xn in registers) */
    Xptr[ 0] = &X00;  Xptr[ 1] = &X01;  Xptr[ 2] = &X02;  Xptr[ 3] = &X03;
    Xptr[ 4] = &X04;  Xptr[ 5] = &X05;  Xptr[ 6] = &X06;  Xptr[ 7] = &X07;
    Xptr[ 8] = &X08;  Xptr[ 9] = &X09;  Xptr[10] = &X10;  Xptr[11] = &X11;
    Xptr[12] = &X12;  Xptr[13] = &X13;  Xptr[14] = &X14;  Xptr[15] = &X15;
#endif

    Skein_assert(blkCnt != 0);                  /* never call with blkCnt == 0! */
    ts[0] = ctx->h.T[0];
    ts[1] = ctx->h.T[1];
    do  {
        /* this implementation only supports 2**64 input bytes (no carry out here) */
        ts[0] += byteCntAdd;                    /* update processed length */

        /* precompute the key schedule for this block */
        ks[ 0] = ctx->X[ 0];
        ks[ 1] = ctx->X[ 1];
        ks[ 2] = ctx->X[ 2];
        ks[ 3] = ctx->X[ 3];
        ks[ 4] = ctx->X[ 4];
        ks[ 5] = ctx->X[ 5];
        ks[ 6] = ctx->X[ 6];
        ks[ 7] = ctx->X[ 7];
        ks[ 8] = ctx->X[ 8];
        ks[ 9] = ctx->X[ 9];
        ks[10] = ctx->X[10];
        ks[11] = ctx->X[11];
        ks[12] = ctx->X[12];
        ks[13] = ctx->X[13];
        ks[14] = ctx->X[14];
        ks[15] = ctx->X[15];
        ks[16] = ks[ 0] ^ ks[ 1] ^ ks[ 2] ^ ks[ 3] ^
                 ks[ 4] ^ ks[ 5] ^ ks[ 6] ^ ks[ 7] ^
                 ks[ 8] ^ ks[ 9] ^ ks[10] ^ ks[11] ^
                 ks[12] ^ ks[13] ^ ks[14] ^ ks[15] ^ SKEIN_KS_PARITY;

        ts[2]  = ts[0] ^ ts[1];

        Skein_Get64_LSB_First(w,blkPtr,WCNT); /* get input block in little-endian format */
        DebugSaveTweak(ctx);
        Skein_Show_Block(BLK_BITS,&ctx->h,ctx->X,blkPtr,w,ks,ts);

        X00    = w[ 0] + ks[ 0];                 /* do the first full key injection */
        X01    = w[ 1] + ks[ 1];
        X02    = w[ 2] + ks[ 2];
        X03    = w[ 3] + ks[ 3];
        X04    = w[ 4] + ks[ 4];
        X05    = w[ 5] + ks[ 5];
        X06    = w[ 6] + ks[ 6];
        X07    = w[ 7] + ks[ 7];
        X08    = w[ 8] + ks[ 8];
        X09    = w[ 9] + ks[ 9];
        X10    = w[10] + ks[10];
        X11    = w[11] + ks[11];
        X12    = w[12] + ks[12];
        X13    = w[13] + ks[13] + ts[0];
        X14    = w[14] + ks[14] + ts[1];
        X15    = w[15] + ks[15];

        Skein_Show_R_Ptr(BLK_BITS,&ctx->h,SKEIN_RND_KEY_INITIAL,Xptr);

#define Round1024(p0,p1,p2,p3,p4,p5,p6,p7,p8,p9,pA,pB,pC,pD,pE,pF,ROT,rNum) \
    X##p0 += X##p1; X##p1 = RotL_64(X##p1,ROT##_0); X##p1 ^= X##p0;   \
    X##p2 += X##p3; X##p3 = RotL_64(X##p3,ROT##_1); X##p3 ^= X##p2;   \
    X##p4 += X##p5; X##p5 = RotL_64(X##p5,ROT##_2); X##p5 ^= X##p4;   \
    X##p6 += X##p7; X##p7 = RotL_64(X##p7,ROT##_3); X##p7 ^= X##p6;   \
    X##p8 += X##p9; X##p9 = RotL_64(X##p9,ROT##_4); X##p9 ^= X##p8;   \
    X##pA += X##pB; X##pB = RotL_64(X##pB,ROT##_5); X##pB ^= X##pA;   \
    X##pC += X##pD; X##pD = RotL_64(X##pD,ROT##_6); X##pD ^= X##pC;   \
    X##pE += X##pF; X##pF = RotL_64(X##pF,ROT##_7); X##pF ^= X##pE;   \

#if SKEIN_UNROLL_1024 == 0                      
#define R1024(p0,p1,p2,p3,p4,p5,p6,p7,p8,p9,pA,pB,pC,pD,pE,pF,ROT,rn) \
    Round1024(p0,p1,p2,p3,p4,p5,p6,p7,p8,p9,pA,pB,pC,pD,pE,pF,ROT,rn) \
    Skein_Show_R_Ptr(BLK_BITS,&ctx->h,rn,Xptr);

#define I1024(R)                                                      \
    X00   += ks[((R)+ 1) % 17]; /* inject the key schedule value */   \
    X01   += ks[((R)+ 2) % 17];                                       \
    X02   += ks[((R)+ 3) % 17];                                       \
    X03   += ks[((R)+ 4) % 17];                                       \
    X04   += ks[((R)+ 5) % 17];                                       \
    X05   += ks[((R)+ 6) % 17];                                       \
    X06   += ks[((R)+ 7) % 17];                                       \
    X07   += ks[((R)+ 8) % 17];                                       \
    X08   += ks[((R)+ 9) % 17];                                       \
    X09   += ks[((R)+10) % 17];                                       \
    X10   += ks[((R)+11) % 17];                                       \
    X11   += ks[((R)+12) % 17];                                       \
    X12   += ks[((R)+13) % 17];                                       \
    X13   += ks[((R)+14) % 17] + ts[((R)+1) % 3];                     \
    X14   += ks[((R)+15) % 17] + ts[((R)+2) % 3];                     \
    X15   += ks[((R)+16) % 17] +     (R)+1;                           \
    Skein_Show_R_Ptr(BLK_BITS,&ctx->h,SKEIN_RND_KEY_INJECT,Xptr); 
#else                                       /* looping version */
#define R1024(p0,p1,p2,p3,p4,p5,p6,p7,p8,p9,pA,pB,pC,pD,pE,pF,ROT,rn) \
    Round1024(p0,p1,p2,p3,p4,p5,p6,p7,p8,p9,pA,pB,pC,pD,pE,pF,ROT,rn) \
    Skein_Show_R_Ptr(BLK_BITS,&ctx->h,4*(r-1)+rn,Xptr);

#define I1024(R)                                                      \
    X00   += ks[r+(R)+ 0];    /* inject the key schedule value */     \
    X01   += ks[r+(R)+ 1];                                            \
    X02   += ks[r+(R)+ 2];                                            \
    X03   += ks[r+(R)+ 3];                                            \
    X04   += ks[r+(R)+ 4];                                            \
    X05   += ks[r+(R)+ 5];                                            \
    X06   += ks[r+(R)+ 6];                                            \
    X07   += ks[r+(R)+ 7];                                            \
    X08   += ks[r+(R)+ 8];                                            \
    X09   += ks[r+(R)+ 9];                                            \
    X10   += ks[r+(R)+10];                                            \
    X11   += ks[r+(R)+11];                                            \
    X12   += ks[r+(R)+12];                                            \
    X13   += ks[r+(R)+13] + ts[r+(R)+0];                              \
    X14   += ks[r+(R)+14] + ts[r+(R)+1];                              \
    X15   += ks[r+(R)+15] +    r+(R)   ;                              \
    ks[r  +       (R)+16] = ks[r+(R)-1];  /* rotate key schedule */   \
    ts[r  +       (R)+ 2] = ts[r+(R)-1];                              \
    Skein_Show_R_Ptr(BLK_BITS,&ctx->h,SKEIN_RND_KEY_INJECT,Xptr);

    for (r=1;r <= 2*RCNT;r+=2*SKEIN_UNROLL_1024)    /* loop thru it */
#endif  
        {
#define R1024_8_rounds(R)    /* do 8 full rounds */                               \
        R1024(00,01,02,03,04,05,06,07,08,09,10,11,12,13,14,15,R1024_0,8*(R) + 1); \
        R1024(00,09,02,13,06,11,04,15,10,07,12,03,14,05,08,01,R1024_1,8*(R) + 2); \
        R1024(00,07,02,05,04,03,06,01,12,15,14,13,08,11,10,09,R1024_2,8*(R) + 3); \
        R1024(00,15,02,11,06,13,04,09,14,01,08,05,10,03,12,07,R1024_3,8*(R) + 4); \
        I1024(2*(R));                                                             \
        R1024(00,01,02,03,04,05,06,07,08,09,10,11,12,13,14,15,R1024_4,8*(R) + 5); \
        R1024(00,09,02,13,06,11,04,15,10,07,12,03,14,05,08,01,R1024_5,8*(R) + 6); \
        R1024(00,07,02,05,04,03,06,01,12,15,14,13,08,11,10,09,R1024_6,8*(R) + 7); \
        R1024(00,15,02,11,06,13,04,09,14,01,08,05,10,03,12,07,R1024_7,8*(R) + 8); \
        I1024(2*(R)+1);

        R1024_8_rounds( 0);

#define R1024_Unroll_R(NN) ((SKEIN_UNROLL_1024 == 0 && SKEIN1024_ROUNDS_TOTAL/8 > (NN)) || (SKEIN_UNROLL_1024 > (NN)))

  #if   R1024_Unroll_R( 1)
        R1024_8_rounds( 1);
  #endif
  #if   R1024_Unroll_R( 2)
        R1024_8_rounds( 2);
  #endif
  #if   R1024_Unroll_R( 3)
        R1024_8_rounds( 3);
  #endif
  #if   R1024_Unroll_R( 4)
        R1024_8_rounds( 4);
  #endif
  #if   R1024_Unroll_R( 5)
        R1024_8_rounds( 5);
  #endif
  #if   R1024_Unroll_R( 6)
        R1024_8_rounds( 6);
  #endif
  #if   R1024_Unroll_R( 7)
        R1024_8_rounds( 7);
  #endif
  #if   R1024_Unroll_R( 8)
        R1024_8_rounds( 8);
  #endif
  #if   R1024_Unroll_R( 9)
        R1024_8_rounds( 9);
  #endif
  #if   R1024_Unroll_R(10)
        R1024_8_rounds(10);
  #endif
  #if   R1024_Unroll_R(11)
        R1024_8_rounds(11);
  #endif
  #if   R1024_Unroll_R(12)
        R1024_8_rounds(12);
  #endif
  #if   R1024_Unroll_R(13)
        R1024_8_rounds(13);
  #endif
  #if   R1024_Unroll_R(14)
        R1024_8_rounds(14);
  #endif
  #if  (SKEIN_UNROLL_1024 > 14)
#error  "need more unrolling in Skein_1024_Process_Block"
  #endif
        }
        /* do the final "feedforward" xor, update context chaining vars */

        ctx->X[ 0] = X00 ^ w[ 0];
        ctx->X[ 1] = X01 ^ w[ 1];
        ctx->X[ 2] = X02 ^ w[ 2];
        ctx->X[ 3] = X03 ^ w[ 3];
        ctx->X[ 4] = X04 ^ w[ 4];
        ctx->X[ 5] = X05 ^ w[ 5];
        ctx->X[ 6] = X06 ^ w[ 6];
        ctx->X[ 7] = X07 ^ w[ 7];
        ctx->X[ 8] = X08 ^ w[ 8];
        ctx->X[ 9] = X09 ^ w[ 9];
        ctx->X[10] = X10 ^ w[10];
        ctx->X[11] = X11 ^ w[11];
        ctx->X[12] = X12 ^ w[12];
        ctx->X[13] = X13 ^ w[13];
        ctx->X[14] = X14 ^ w[14];
        ctx->X[15] = X15 ^ w[15];

        Skein_Show_Round(BLK_BITS,&ctx->h,SKEIN_RND_FEED_FWD,ctx->X);
        
        ts[1] &= ~SKEIN_T1_FLAG_FIRST;
        blkPtr += SKEIN1024_BLOCK_BYTES;
        }
    while (--blkCnt);
    ctx->h.T[0] = ts[0];
    ctx->h.T[1] = ts[1];
    }

#if defined(SKEIN_CODE_SIZE) || defined(SKEIN_PERF)
static size_t Skein1024_Process_Block_CodeSize(void)
    {
    return ((u08b_t *) Skein1024_Process_Block_CodeSize) -
           ((u08b_t *) Skein1024_Process_Block);
    }
static uint_t Skein1024_Unroll_Cnt(void)
    {
    return SKEIN_UNROLL_1024;
    }
#endif
#endif


#if 0
/*****************************************************************/
/*     256-bit Skein                                             */
/*****************************************************************/

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* init the context for a straight hashing operation  */
static int Skein_256_Init(Skein_256_Ctxt_t *ctx, size_t hashBitLen)
    {
    union
        {
        u08b_t  b[SKEIN_256_STATE_BYTES];
        u64b_t  w[SKEIN_256_STATE_WORDS];
        } cfg;                              /* config block */
        
    Skein_Assert(hashBitLen > 0,SKEIN_BAD_HASHLEN);
    ctx->h.hashBitLen = hashBitLen;         /* output hash bit count */

    switch (hashBitLen)
        {             /* use pre-computed values, where available */
#ifndef SKEIN_NO_PRECOMP
        case  256: memcpy(ctx->X,SKEIN_256_IV_256,sizeof(ctx->X));  break;
        case  224: memcpy(ctx->X,SKEIN_256_IV_224,sizeof(ctx->X));  break;
        case  160: memcpy(ctx->X,SKEIN_256_IV_160,sizeof(ctx->X));  break;
        case  128: memcpy(ctx->X,SKEIN_256_IV_128,sizeof(ctx->X));  break;
#endif
        default:
            /* here if there is no precomputed IV value available */
            /* build/process the config block, type == CONFIG (could be precomputed) */
            Skein_Start_New_Type(ctx,CFG_FINAL);        /* set tweaks: T0=0; T1=CFG | FINAL */

            cfg.w[0] = Skein_Swap64(SKEIN_SCHEMA_VER);  /* set the schema, version */
            cfg.w[1] = Skein_Swap64(hashBitLen);        /* hash result length in bits */
            cfg.w[2] = Skein_Swap64(SKEIN_CFG_TREE_INFO_SEQUENTIAL);
            memset(&cfg.w[3],0,sizeof(cfg) - 3*sizeof(cfg.w[0])); /* zero pad config block */

            /* compute the initial chaining values from config block */
            memset(ctx->X,0,sizeof(ctx->X));            /* zero the chaining variables */
            Skein_256_Process_Block(ctx,cfg.b,1,SKEIN_CFG_STR_LEN);
            break;
        }
    /* The chaining vars ctx->X are now initialized for the given hashBitLen. */
    /* Set up to process the data message portion of the hash (default) */
    Skein_Start_New_Type(ctx,MSG);              /* T0=0, T1= MSG type */

    return SKEIN_SUCCESS;
    }

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* init the context for a MAC and/or tree hash operation */
/* [identical to Skein_256_Init() when keyBytes == 0 && treeInfo == SKEIN_CFG_TREE_INFO_SEQUENTIAL] */
static int Skein_256_InitExt(Skein_256_Ctxt_t *ctx,size_t hashBitLen,u64b_t treeInfo, const u08b_t *key, size_t keyBytes)
    {
    union
        {
        u08b_t  b[SKEIN_256_STATE_BYTES];
        u64b_t  w[SKEIN_256_STATE_WORDS];
        } cfg;                              /* config block */
        
    Skein_Assert(hashBitLen > 0,SKEIN_BAD_HASHLEN);
    Skein_Assert(keyBytes == 0 || key != NULL,SKEIN_FAIL);

    /* compute the initial chaining values ctx->X[], based on key */
    if (keyBytes == 0)                          /* is there a key? */
        {                                   
        memset(ctx->X,0,sizeof(ctx->X));        /* no key: use all zeroes as key for config block */
        }
    else                                        /* here to pre-process a key */
        {
        Skein_assert(sizeof(cfg.b) >= sizeof(ctx->X));
        /* do a mini-Init right here */
        ctx->h.hashBitLen=8*sizeof(ctx->X);     /* set output hash bit count = state size */
        Skein_Start_New_Type(ctx,KEY);          /* set tweaks: T0 = 0; T1 = KEY type */
        memset(ctx->X,0,sizeof(ctx->X));        /* zero the initial chaining variables */
        Skein_256_Update(ctx,key,keyBytes);     /* hash the key */
        Skein_256_Final_Pad(ctx,cfg.b);         /* put result into cfg.b[] */
        memcpy(ctx->X,cfg.b,sizeof(cfg.b));     /* copy over into ctx->X[] */
#if SKEIN_NEED_SWAP
        {
        uint_t i;
        for (i=0;i<SKEIN_256_STATE_WORDS;i++)   /* convert key bytes to context words */
            ctx->X[i] = Skein_Swap64(ctx->X[i]);
        }
#endif
        }
    /* build/process the config block, type == CONFIG (could be precomputed for each key) */
    ctx->h.hashBitLen = hashBitLen;             /* output hash bit count */
    Skein_Start_New_Type(ctx,CFG_FINAL);

    memset(&cfg.w,0,sizeof(cfg.w));             /* pre-pad cfg.w[] with zeroes */
    cfg.w[0] = Skein_Swap64(SKEIN_SCHEMA_VER);
    cfg.w[1] = Skein_Swap64(hashBitLen);        /* hash result length in bits */
    cfg.w[2] = Skein_Swap64(treeInfo);          /* tree hash config info (or SKEIN_CFG_TREE_INFO_SEQUENTIAL) */

    Skein_Show_Key(256,&ctx->h,key,keyBytes);

    /* compute the initial chaining values from config block */
    Skein_256_Process_Block(ctx,cfg.b,1,SKEIN_CFG_STR_LEN);

    /* The chaining vars ctx->X are now initialized */
    /* Set up to process the data message portion of the hash (default) */
    ctx->h.bCnt = 0;                            /* buffer b[] starts out empty */
    Skein_Start_New_Type(ctx,MSG);
    
    return SKEIN_SUCCESS;
    }
#endif

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* process the input bytes */
static int Skein_256_Update(Skein_256_Ctxt_t *ctx, const u08b_t *msg, size_t msgByteCnt)
    {
    size_t n;

    Skein_Assert(ctx->h.bCnt <= SKEIN_256_BLOCK_BYTES,SKEIN_FAIL);    /* catch uninitialized context */

    /* process full blocks, if any */
    if (msgByteCnt + ctx->h.bCnt > SKEIN_256_BLOCK_BYTES)
        {
        if (ctx->h.bCnt)                              /* finish up any buffered message data */
            {
            n = SKEIN_256_BLOCK_BYTES - ctx->h.bCnt;  /* # bytes free in buffer b[] */
            if (n)
                {
                Skein_assert(n < msgByteCnt);         /* check on our logic here */
                memcpy(&ctx->b[ctx->h.bCnt],msg,n);
                msgByteCnt  -= n;
                msg         += n;
                ctx->h.bCnt += n;
                }
            Skein_assert(ctx->h.bCnt == SKEIN_256_BLOCK_BYTES);
            Skein_256_Process_Block(ctx,ctx->b,1,SKEIN_256_BLOCK_BYTES);
            ctx->h.bCnt = 0;
            }
        /* now process any remaining full blocks, directly from input message data */
        if (msgByteCnt > SKEIN_256_BLOCK_BYTES)
            {
            n = (msgByteCnt-1) / SKEIN_256_BLOCK_BYTES;   /* number of full blocks to process */
            Skein_256_Process_Block(ctx,msg,n,SKEIN_256_BLOCK_BYTES);
            msgByteCnt -= n * SKEIN_256_BLOCK_BYTES;
            msg        += n * SKEIN_256_BLOCK_BYTES;
            }
        Skein_assert(ctx->h.bCnt == 0);
        }

    /* copy any remaining source message data bytes into b[] */
    if (msgByteCnt)
        {
        Skein_assert(msgByteCnt + ctx->h.bCnt <= SKEIN_256_BLOCK_BYTES);
        memcpy(&ctx->b[ctx->h.bCnt],msg,msgByteCnt);
        ctx->h.bCnt += msgByteCnt;
        }

    return SKEIN_SUCCESS;
    }
   
/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* finalize the hash computation and output the result */
static int Skein_256_Final(Skein_256_Ctxt_t *ctx, u08b_t *hashVal)
    {
    size_t i,n,byteCnt;
    u64b_t X[SKEIN_256_STATE_WORDS];
    Skein_Assert(ctx->h.bCnt <= SKEIN_256_BLOCK_BYTES,SKEIN_FAIL);    /* catch uninitialized context */

    ctx->h.T[1] |= SKEIN_T1_FLAG_FINAL;                 /* tag as the final block */
    if (ctx->h.bCnt < SKEIN_256_BLOCK_BYTES)            /* zero pad b[] if necessary */
        memset(&ctx->b[ctx->h.bCnt],0,SKEIN_256_BLOCK_BYTES - ctx->h.bCnt);

    Skein_256_Process_Block(ctx,ctx->b,1,ctx->h.bCnt);  /* process the final block */
    
    /* now output the result */
    byteCnt = (ctx->h.hashBitLen + 7) >> 3;             /* total number of output bytes */

    /* run Threefish in "counter mode" to generate output */
    memset(ctx->b,0,sizeof(ctx->b));  /* zero out b[], so it can hold the counter */
    memcpy(X,ctx->X,sizeof(X));       /* keep a local copy of counter mode "key" */
    for (i=0;i*SKEIN_256_BLOCK_BYTES < byteCnt;i++)
        {
        ((u64b_t *)ctx->b)[0]= Skein_Swap64((u64b_t) i); /* build the counter block */
        Skein_Start_New_Type(ctx,OUT_FINAL);
        Skein_256_Process_Block(ctx,ctx->b,1,sizeof(u64b_t)); /* run "counter mode" */
        n = byteCnt - i*SKEIN_256_BLOCK_BYTES;   /* number of output bytes left to go */
        if (n >= SKEIN_256_BLOCK_BYTES)
            n  = SKEIN_256_BLOCK_BYTES;
        Skein_Put64_LSB_First(hashVal+i*SKEIN_256_BLOCK_BYTES,ctx->X,n);   /* "output" the ctr mode bytes */
        Skein_Show_Final(256,&ctx->h,n,hashVal+i*SKEIN_256_BLOCK_BYTES);
        memcpy(ctx->X,X,sizeof(X));   /* restore the counter mode key for next time */
        }
    return SKEIN_SUCCESS;
    }

#if defined(SKEIN_CODE_SIZE) || defined(SKEIN_PERF)
static size_t Skein_256_API_CodeSize(void)
    {
    return ((u08b_t *) Skein_256_API_CodeSize) -
           ((u08b_t *) Skein_256_Init);
    }
#endif

/*****************************************************************/
/*     512-bit Skein                                             */
/*****************************************************************/

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* init the context for a straight hashing operation  */
static int Skein_512_Init(Skein_512_Ctxt_t *ctx, size_t hashBitLen)
    {
    union
        {
        u08b_t  b[SKEIN_512_STATE_BYTES];
        u64b_t  w[SKEIN_512_STATE_WORDS];
        } cfg;                              /* config block */
        
    Skein_Assert(hashBitLen > 0,SKEIN_BAD_HASHLEN);
    ctx->h.hashBitLen = hashBitLen;         /* output hash bit count */

    switch (hashBitLen)
        {             /* use pre-computed values, where available */
#ifndef SKEIN_NO_PRECOMP
        case  512: memcpy(ctx->X,SKEIN_512_IV_512,sizeof(ctx->X));  break;
        case  384: memcpy(ctx->X,SKEIN_512_IV_384,sizeof(ctx->X));  break;
        case  256: memcpy(ctx->X,SKEIN_512_IV_256,sizeof(ctx->X));  break;
        case  224: memcpy(ctx->X,SKEIN_512_IV_224,sizeof(ctx->X));  break;
#endif
        default:
            /* here if there is no precomputed IV value available */
            /* build/process the config block, type == CONFIG (could be precomputed) */
            Skein_Start_New_Type(ctx,CFG_FINAL);        /* set tweaks: T0=0; T1=CFG | FINAL */

            cfg.w[0] = Skein_Swap64(SKEIN_SCHEMA_VER);  /* set the schema, version */
            cfg.w[1] = Skein_Swap64(hashBitLen);        /* hash result length in bits */
            cfg.w[2] = Skein_Swap64(SKEIN_CFG_TREE_INFO_SEQUENTIAL);
            memset(&cfg.w[3],0,sizeof(cfg) - 3*sizeof(cfg.w[0])); /* zero pad config block */

            /* compute the initial chaining values from config block */
            memset(ctx->X,0,sizeof(ctx->X));            /* zero the chaining variables */
            Skein_512_Process_Block(ctx,cfg.b,1,SKEIN_CFG_STR_LEN);
            break;
        }

    /* The chaining vars ctx->X are now initialized for the given hashBitLen. */
    /* Set up to process the data message portion of the hash (default) */
    Skein_Start_New_Type(ctx,MSG);              /* T0=0, T1= MSG type */

    return SKEIN_SUCCESS;
    }

#if 0
/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* init the context for a MAC and/or tree hash operation */
/* [identical to Skein_512_Init() when keyBytes == 0 && treeInfo == SKEIN_CFG_TREE_INFO_SEQUENTIAL] */
static int Skein_512_InitExt(Skein_512_Ctxt_t *ctx,size_t hashBitLen,u64b_t treeInfo, const u08b_t *key, size_t keyBytes)
    {
    union
        {
        u08b_t  b[SKEIN_512_STATE_BYTES];
        u64b_t  w[SKEIN_512_STATE_WORDS];
        } cfg;                              /* config block */
        
    Skein_Assert(hashBitLen > 0,SKEIN_BAD_HASHLEN);
    Skein_Assert(keyBytes == 0 || key != NULL,SKEIN_FAIL);

    /* compute the initial chaining values ctx->X[], based on key */
    if (keyBytes == 0)                          /* is there a key? */
        {                                   
        memset(ctx->X,0,sizeof(ctx->X));        /* no key: use all zeroes as key for config block */
        }
    else                                        /* here to pre-process a key */
        {
        Skein_assert(sizeof(cfg.b) >= sizeof(ctx->X));
        /* do a mini-Init right here */
        ctx->h.hashBitLen=8*sizeof(ctx->X);     /* set output hash bit count = state size */
        Skein_Start_New_Type(ctx,KEY);          /* set tweaks: T0 = 0; T1 = KEY type */
        memset(ctx->X,0,sizeof(ctx->X));        /* zero the initial chaining variables */
        Skein_512_Update(ctx,key,keyBytes);     /* hash the key */
        Skein_512_Final_Pad(ctx,cfg.b);         /* put result into cfg.b[] */
        memcpy(ctx->X,cfg.b,sizeof(cfg.b));     /* copy over into ctx->X[] */
#if SKEIN_NEED_SWAP
        {
        uint_t i;
        for (i=0;i<SKEIN_512_STATE_WORDS;i++)   /* convert key bytes to context words */
            ctx->X[i] = Skein_Swap64(ctx->X[i]);
        }
#endif
        }
    /* build/process the config block, type == CONFIG (could be precomputed for each key) */
    ctx->h.hashBitLen = hashBitLen;             /* output hash bit count */
    Skein_Start_New_Type(ctx,CFG_FINAL);

    memset(&cfg.w,0,sizeof(cfg.w));             /* pre-pad cfg.w[] with zeroes */
    cfg.w[0] = Skein_Swap64(SKEIN_SCHEMA_VER);
    cfg.w[1] = Skein_Swap64(hashBitLen);        /* hash result length in bits */
    cfg.w[2] = Skein_Swap64(treeInfo);          /* tree hash config info (or SKEIN_CFG_TREE_INFO_SEQUENTIAL) */

    Skein_Show_Key(512,&ctx->h,key,keyBytes);

    /* compute the initial chaining values from config block */
    Skein_512_Process_Block(ctx,cfg.b,1,SKEIN_CFG_STR_LEN);

    /* The chaining vars ctx->X are now initialized */
    /* Set up to process the data message portion of the hash (default) */
    ctx->h.bCnt = 0;                            /* buffer b[] starts out empty */
    Skein_Start_New_Type(ctx,MSG);
    
    return SKEIN_SUCCESS;
    }
#endif

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* process the input bytes */
static int Skein_512_Update(Skein_512_Ctxt_t *ctx, const u08b_t *msg, size_t msgByteCnt)
    {
    size_t n;

    Skein_Assert(ctx->h.bCnt <= SKEIN_512_BLOCK_BYTES,SKEIN_FAIL);    /* catch uninitialized context */

    /* process full blocks, if any */
    if (msgByteCnt + ctx->h.bCnt > SKEIN_512_BLOCK_BYTES)
        {
        if (ctx->h.bCnt)                              /* finish up any buffered message data */
            {
            n = SKEIN_512_BLOCK_BYTES - ctx->h.bCnt;  /* # bytes free in buffer b[] */
            if (n)
                {
                Skein_assert(n < msgByteCnt);         /* check on our logic here */
                memcpy(&ctx->b[ctx->h.bCnt],msg,n);
                msgByteCnt  -= n;
                msg         += n;
                ctx->h.bCnt += n;
                }
            Skein_assert(ctx->h.bCnt == SKEIN_512_BLOCK_BYTES);
            Skein_512_Process_Block(ctx,ctx->b,1,SKEIN_512_BLOCK_BYTES);
            ctx->h.bCnt = 0;
            }
        /* now process any remaining full blocks, directly from input message data */
        if (msgByteCnt > SKEIN_512_BLOCK_BYTES)
            {
            n = (msgByteCnt-1) / SKEIN_512_BLOCK_BYTES;   /* number of full blocks to process */
            Skein_512_Process_Block(ctx,msg,n,SKEIN_512_BLOCK_BYTES);
            msgByteCnt -= n * SKEIN_512_BLOCK_BYTES;
            msg        += n * SKEIN_512_BLOCK_BYTES;
            }
        Skein_assert(ctx->h.bCnt == 0);
        }

    /* copy any remaining source message data bytes into b[] */
    if (msgByteCnt)
        {
        Skein_assert(msgByteCnt + ctx->h.bCnt <= SKEIN_512_BLOCK_BYTES);
        memcpy(&ctx->b[ctx->h.bCnt],msg,msgByteCnt);
        ctx->h.bCnt += msgByteCnt;
        }

    return SKEIN_SUCCESS;
    }
   
/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* finalize the hash computation and output the result */
static int Skein_512_Final(Skein_512_Ctxt_t *ctx, u08b_t *hashVal)
    {
    size_t i,n,byteCnt;
    u64b_t X[SKEIN_512_STATE_WORDS];
    Skein_Assert(ctx->h.bCnt <= SKEIN_512_BLOCK_BYTES,SKEIN_FAIL);    /* catch uninitialized context */

    ctx->h.T[1] |= SKEIN_T1_FLAG_FINAL;                 /* tag as the final block */
    if (ctx->h.bCnt < SKEIN_512_BLOCK_BYTES)            /* zero pad b[] if necessary */
        memset(&ctx->b[ctx->h.bCnt],0,SKEIN_512_BLOCK_BYTES - ctx->h.bCnt);

    Skein_512_Process_Block(ctx,ctx->b,1,ctx->h.bCnt);  /* process the final block */
    
    /* now output the result */
    byteCnt = (ctx->h.hashBitLen + 7) >> 3;             /* total number of output bytes */

    /* run Threefish in "counter mode" to generate output */
    memset(ctx->b,0,sizeof(ctx->b));  /* zero out b[], so it can hold the counter */
    memcpy(X,ctx->X,sizeof(X));       /* keep a local copy of counter mode "key" */
    for (i=0;i*SKEIN_512_BLOCK_BYTES < byteCnt;i++)
        {
        ((u64b_t *)ctx->b)[0]= Skein_Swap64((u64b_t) i); /* build the counter block */
        Skein_Start_New_Type(ctx,OUT_FINAL);
        Skein_512_Process_Block(ctx,ctx->b,1,sizeof(u64b_t)); /* run "counter mode" */
        n = byteCnt - i*SKEIN_512_BLOCK_BYTES;   /* number of output bytes left to go */
        if (n >= SKEIN_512_BLOCK_BYTES)
            n  = SKEIN_512_BLOCK_BYTES;
        Skein_Put64_LSB_First(hashVal+i*SKEIN_512_BLOCK_BYTES,ctx->X,n);   /* "output" the ctr mode bytes */
        Skein_Show_Final(512,&ctx->h,n,hashVal+i*SKEIN_512_BLOCK_BYTES);
        memcpy(ctx->X,X,sizeof(X));   /* restore the counter mode key for next time */
        }
    return SKEIN_SUCCESS;
    }

#if defined(SKEIN_CODE_SIZE) || defined(SKEIN_PERF)
static size_t Skein_512_API_CodeSize(void)
    {
    return ((u08b_t *) Skein_512_API_CodeSize) -
           ((u08b_t *) Skein_512_Init);
    }
#endif

/*****************************************************************/
/*    1024-bit Skein                                             */
/*****************************************************************/
/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* init the context for a straight hashing operation  */
static int Skein1024_Init(Skein1024_Ctxt_t *ctx, size_t hashBitLen)
    {
    union
        {
        u08b_t  b[SKEIN1024_STATE_BYTES];
        u64b_t  w[SKEIN1024_STATE_WORDS];
        } cfg;                              /* config block */
        
    Skein_Assert(hashBitLen > 0,SKEIN_BAD_HASHLEN);
    ctx->h.hashBitLen = hashBitLen;         /* output hash bit count */

    switch (hashBitLen)
        {              /* use pre-computed values, where available */
#ifndef SKEIN_NO_PRECOMP
        case  512: memcpy(ctx->X,SKEIN1024_IV_512 ,sizeof(ctx->X)); break;
        case  384: memcpy(ctx->X,SKEIN1024_IV_384 ,sizeof(ctx->X)); break;
        case 1024: memcpy(ctx->X,SKEIN1024_IV_1024,sizeof(ctx->X)); break;
#endif
        default:
            /* here if there is no precomputed IV value available */
            /* build/process the config block, type == CONFIG (could be precomputed) */
            Skein_Start_New_Type(ctx,CFG_FINAL);        /* set tweaks: T0=0; T1=CFG | FINAL */

            cfg.w[0] = Skein_Swap64(SKEIN_SCHEMA_VER);  /* set the schema, version */
            cfg.w[1] = Skein_Swap64(hashBitLen);        /* hash result length in bits */
            cfg.w[2] = Skein_Swap64(SKEIN_CFG_TREE_INFO_SEQUENTIAL);
            memset(&cfg.w[3],0,sizeof(cfg) - 3*sizeof(cfg.w[0])); /* zero pad config block */

            /* compute the initial chaining values from config block */
            memset(ctx->X,0,sizeof(ctx->X));            /* zero the chaining variables */
            Skein1024_Process_Block(ctx,cfg.b,1,SKEIN_CFG_STR_LEN);
            break;
        }

    /* The chaining vars ctx->X are now initialized for the given hashBitLen. */
    /* Set up to process the data message portion of the hash (default) */
    Skein_Start_New_Type(ctx,MSG);              /* T0=0, T1= MSG type */

    return SKEIN_SUCCESS;
    }

#if 0
/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* init the context for a MAC and/or tree hash operation */
/* [identical to Skein1024_Init() when keyBytes == 0 && treeInfo == SKEIN_CFG_TREE_INFO_SEQUENTIAL] */
static int Skein1024_InitExt(Skein1024_Ctxt_t *ctx,size_t hashBitLen,u64b_t treeInfo, const u08b_t *key, size_t keyBytes)
    {
    union
        {
        u08b_t  b[SKEIN1024_STATE_BYTES];
        u64b_t  w[SKEIN1024_STATE_WORDS];
        } cfg;                              /* config block */
        
    Skein_Assert(hashBitLen > 0,SKEIN_BAD_HASHLEN);
    Skein_Assert(keyBytes == 0 || key != NULL,SKEIN_FAIL);

    /* compute the initial chaining values ctx->X[], based on key */
    if (keyBytes == 0)                          /* is there a key? */
        {                                   
        memset(ctx->X,0,sizeof(ctx->X));        /* no key: use all zeroes as key for config block */
        }
    else                                        /* here to pre-process a key */
        {
        Skein_assert(sizeof(cfg.b) >= sizeof(ctx->X));
        /* do a mini-Init right here */
        ctx->h.hashBitLen=8*sizeof(ctx->X);     /* set output hash bit count = state size */
        Skein_Start_New_Type(ctx,KEY);          /* set tweaks: T0 = 0; T1 = KEY type */
        memset(ctx->X,0,sizeof(ctx->X));        /* zero the initial chaining variables */
        Skein1024_Update(ctx,key,keyBytes);     /* hash the key */
        Skein1024_Final_Pad(ctx,cfg.b);         /* put result into cfg.b[] */
        memcpy(ctx->X,cfg.b,sizeof(cfg.b));     /* copy over into ctx->X[] */
#if SKEIN_NEED_SWAP
        {
        uint_t i;
        for (i=0;i<SKEIN1024_STATE_WORDS;i++)   /* convert key bytes to context words */
            ctx->X[i] = Skein_Swap64(ctx->X[i]);
        }
#endif
        }
    /* build/process the config block, type == CONFIG (could be precomputed for each key) */
    ctx->h.hashBitLen = hashBitLen;             /* output hash bit count */
    Skein_Start_New_Type(ctx,CFG_FINAL);

    memset(&cfg.w,0,sizeof(cfg.w));             /* pre-pad cfg.w[] with zeroes */
    cfg.w[0] = Skein_Swap64(SKEIN_SCHEMA_VER);
    cfg.w[1] = Skein_Swap64(hashBitLen);        /* hash result length in bits */
    cfg.w[2] = Skein_Swap64(treeInfo);          /* tree hash config info (or SKEIN_CFG_TREE_INFO_SEQUENTIAL) */

    Skein_Show_Key(1024,&ctx->h,key,keyBytes);

    /* compute the initial chaining values from config block */
    Skein1024_Process_Block(ctx,cfg.b,1,SKEIN_CFG_STR_LEN);

    /* The chaining vars ctx->X are now initialized */
    /* Set up to process the data message portion of the hash (default) */
    ctx->h.bCnt = 0;                            /* buffer b[] starts out empty */
    Skein_Start_New_Type(ctx,MSG);
    
    return SKEIN_SUCCESS;
    }
#endif

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* process the input bytes */
static int Skein1024_Update(Skein1024_Ctxt_t *ctx, const u08b_t *msg, size_t msgByteCnt)
    {
    size_t n;

    Skein_Assert(ctx->h.bCnt <= SKEIN1024_BLOCK_BYTES,SKEIN_FAIL);    /* catch uninitialized context */

    /* process full blocks, if any */
    if (msgByteCnt + ctx->h.bCnt > SKEIN1024_BLOCK_BYTES)
        {
        if (ctx->h.bCnt)                              /* finish up any buffered message data */
            {
            n = SKEIN1024_BLOCK_BYTES - ctx->h.bCnt;  /* # bytes free in buffer b[] */
            if (n)
                {
                Skein_assert(n < msgByteCnt);         /* check on our logic here */
                memcpy(&ctx->b[ctx->h.bCnt],msg,n);
                msgByteCnt  -= n;
                msg         += n;
                ctx->h.bCnt += n;
                }
            Skein_assert(ctx->h.bCnt == SKEIN1024_BLOCK_BYTES);
            Skein1024_Process_Block(ctx,ctx->b,1,SKEIN1024_BLOCK_BYTES);
            ctx->h.bCnt = 0;
            }
        /* now process any remaining full blocks, directly from input message data */
        if (msgByteCnt > SKEIN1024_BLOCK_BYTES)
            {
            n = (msgByteCnt-1) / SKEIN1024_BLOCK_BYTES;   /* number of full blocks to process */
            Skein1024_Process_Block(ctx,msg,n,SKEIN1024_BLOCK_BYTES);
            msgByteCnt -= n * SKEIN1024_BLOCK_BYTES;
            msg        += n * SKEIN1024_BLOCK_BYTES;
            }
        Skein_assert(ctx->h.bCnt == 0);
        }

    /* copy any remaining source message data bytes into b[] */
    if (msgByteCnt)
        {
        Skein_assert(msgByteCnt + ctx->h.bCnt <= SKEIN1024_BLOCK_BYTES);
        memcpy(&ctx->b[ctx->h.bCnt],msg,msgByteCnt);
        ctx->h.bCnt += msgByteCnt;
        }

    return SKEIN_SUCCESS;
    }
   
/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* finalize the hash computation and output the result */
static int Skein1024_Final(Skein1024_Ctxt_t *ctx, u08b_t *hashVal)
    {
    size_t i,n,byteCnt;
    u64b_t X[SKEIN1024_STATE_WORDS];
    Skein_Assert(ctx->h.bCnt <= SKEIN1024_BLOCK_BYTES,SKEIN_FAIL);    /* catch uninitialized context */

    ctx->h.T[1] |= SKEIN_T1_FLAG_FINAL;                 /* tag as the final block */
    if (ctx->h.bCnt < SKEIN1024_BLOCK_BYTES)            /* zero pad b[] if necessary */
        memset(&ctx->b[ctx->h.bCnt],0,SKEIN1024_BLOCK_BYTES - ctx->h.bCnt);

    Skein1024_Process_Block(ctx,ctx->b,1,ctx->h.bCnt);  /* process the final block */
    
    /* now output the result */
    byteCnt = (ctx->h.hashBitLen + 7) >> 3;             /* total number of output bytes */

    /* run Threefish in "counter mode" to generate output */
    memset(ctx->b,0,sizeof(ctx->b));  /* zero out b[], so it can hold the counter */
    memcpy(X,ctx->X,sizeof(X));       /* keep a local copy of counter mode "key" */
    for (i=0;i*SKEIN1024_BLOCK_BYTES < byteCnt;i++)
        {
        ((u64b_t *)ctx->b)[0]= Skein_Swap64((u64b_t) i); /* build the counter block */
        Skein_Start_New_Type(ctx,OUT_FINAL);
        Skein1024_Process_Block(ctx,ctx->b,1,sizeof(u64b_t)); /* run "counter mode" */
        n = byteCnt - i*SKEIN1024_BLOCK_BYTES;   /* number of output bytes left to go */
        if (n >= SKEIN1024_BLOCK_BYTES)
            n  = SKEIN1024_BLOCK_BYTES;
        Skein_Put64_LSB_First(hashVal+i*SKEIN1024_BLOCK_BYTES,ctx->X,n);   /* "output" the ctr mode bytes */
        Skein_Show_Final(1024,&ctx->h,n,hashVal+i*SKEIN1024_BLOCK_BYTES);
        memcpy(ctx->X,X,sizeof(X));   /* restore the counter mode key for next time */
        }
    return SKEIN_SUCCESS;
    }

#if defined(SKEIN_CODE_SIZE) || defined(SKEIN_PERF)
static size_t Skein1024_API_CodeSize(void)
    {
    return ((u08b_t *) Skein1024_API_CodeSize) -
           ((u08b_t *) Skein1024_Init);
    }
#endif

/**************** Functions to support MAC/tree hashing ***************/
/*   (this code is identical for Optimized and Reference versions)    */

#if 0
/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* finalize the hash computation and output the block, no OUTPUT stage */
static int Skein_256_Final_Pad(Skein_256_Ctxt_t *ctx, u08b_t *hashVal)
    {
    Skein_Assert(ctx->h.bCnt <= SKEIN_256_BLOCK_BYTES,SKEIN_FAIL);    /* catch uninitialized context */

    ctx->h.T[1] |= SKEIN_T1_FLAG_FINAL;        /* tag as the final block */
    if (ctx->h.bCnt < SKEIN_256_BLOCK_BYTES)   /* zero pad b[] if necessary */
        memset(&ctx->b[ctx->h.bCnt],0,SKEIN_256_BLOCK_BYTES - ctx->h.bCnt);
    Skein_256_Process_Block(ctx,ctx->b,1,ctx->h.bCnt);    /* process the final block */
    
    Skein_Put64_LSB_First(hashVal,ctx->X,SKEIN_256_BLOCK_BYTES);   /* "output" the state bytes */
    
    return SKEIN_SUCCESS;
    }

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* finalize the hash computation and output the block, no OUTPUT stage */
static int Skein_512_Final_Pad(Skein_512_Ctxt_t *ctx, u08b_t *hashVal)
    {
    Skein_Assert(ctx->h.bCnt <= SKEIN_512_BLOCK_BYTES,SKEIN_FAIL);    /* catch uninitialized context */

    ctx->h.T[1] |= SKEIN_T1_FLAG_FINAL;        /* tag as the final block */
    if (ctx->h.bCnt < SKEIN_512_BLOCK_BYTES)   /* zero pad b[] if necessary */
        memset(&ctx->b[ctx->h.bCnt],0,SKEIN_512_BLOCK_BYTES - ctx->h.bCnt);
    Skein_512_Process_Block(ctx,ctx->b,1,ctx->h.bCnt);    /* process the final block */
    
    Skein_Put64_LSB_First(hashVal,ctx->X,SKEIN_512_BLOCK_BYTES);   /* "output" the state bytes */
    
    return SKEIN_SUCCESS;
    }

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* finalize the hash computation and output the block, no OUTPUT stage */
static int Skein1024_Final_Pad(Skein1024_Ctxt_t *ctx, u08b_t *hashVal)
    {
    Skein_Assert(ctx->h.bCnt <= SKEIN1024_BLOCK_BYTES,SKEIN_FAIL);    /* catch uninitialized context */

    ctx->h.T[1] |= SKEIN_T1_FLAG_FINAL;        /* tag as the final block */
    if (ctx->h.bCnt < SKEIN1024_BLOCK_BYTES)   /* zero pad b[] if necessary */
        memset(&ctx->b[ctx->h.bCnt],0,SKEIN1024_BLOCK_BYTES - ctx->h.bCnt);
    Skein1024_Process_Block(ctx,ctx->b,1,ctx->h.bCnt);    /* process the final block */
    
    Skein_Put64_LSB_First(hashVal,ctx->X,SKEIN1024_BLOCK_BYTES);   /* "output" the state bytes */
    
    return SKEIN_SUCCESS;
    }


#if SKEIN_TREE_HASH
/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* just do the OUTPUT stage                                       */
static int Skein_256_Output(Skein_256_Ctxt_t *ctx, u08b_t *hashVal)
    {
    size_t i,n,byteCnt;
    u64b_t X[SKEIN_256_STATE_WORDS];
    Skein_Assert(ctx->h.bCnt <= SKEIN_256_BLOCK_BYTES,SKEIN_FAIL);    /* catch uninitialized context */

    /* now output the result */
    byteCnt = (ctx->h.hashBitLen + 7) >> 3;    /* total number of output bytes */

    /* run Threefish in "counter mode" to generate output */
    memset(ctx->b,0,sizeof(ctx->b));  /* zero out b[], so it can hold the counter */
    memcpy(X,ctx->X,sizeof(X));       /* keep a local copy of counter mode "key" */
    for (i=0;i*SKEIN_256_BLOCK_BYTES < byteCnt;i++)
        {
        ((u64b_t *)ctx->b)[0]= Skein_Swap64((u64b_t) i); /* build the counter block */
        Skein_Start_New_Type(ctx,OUT_FINAL);
        Skein_256_Process_Block(ctx,ctx->b,1,sizeof(u64b_t)); /* run "counter mode" */
        n = byteCnt - i*SKEIN_256_BLOCK_BYTES;   /* number of output bytes left to go */
        if (n >= SKEIN_256_BLOCK_BYTES)
            n  = SKEIN_256_BLOCK_BYTES;
        Skein_Put64_LSB_First(hashVal+i*SKEIN_256_BLOCK_BYTES,ctx->X,n);   /* "output" the ctr mode bytes */
        Skein_Show_Final(256,&ctx->h,n,hashVal+i*SKEIN_256_BLOCK_BYTES);
        memcpy(ctx->X,X,sizeof(X));   /* restore the counter mode key for next time */
        }
    return SKEIN_SUCCESS;
    }

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* just do the OUTPUT stage                                       */
static int Skein_512_Output(Skein_512_Ctxt_t *ctx, u08b_t *hashVal)
    {
    size_t i,n,byteCnt;
    u64b_t X[SKEIN_512_STATE_WORDS];
    Skein_Assert(ctx->h.bCnt <= SKEIN_512_BLOCK_BYTES,SKEIN_FAIL);    /* catch uninitialized context */

    /* now output the result */
    byteCnt = (ctx->h.hashBitLen + 7) >> 3;    /* total number of output bytes */

    /* run Threefish in "counter mode" to generate output */
    memset(ctx->b,0,sizeof(ctx->b));  /* zero out b[], so it can hold the counter */
    memcpy(X,ctx->X,sizeof(X));       /* keep a local copy of counter mode "key" */
    for (i=0;i*SKEIN_512_BLOCK_BYTES < byteCnt;i++)
        {
        ((u64b_t *)ctx->b)[0]= Skein_Swap64((u64b_t) i); /* build the counter block */
        Skein_Start_New_Type(ctx,OUT_FINAL);
        Skein_512_Process_Block(ctx,ctx->b,1,sizeof(u64b_t)); /* run "counter mode" */
        n = byteCnt - i*SKEIN_512_BLOCK_BYTES;   /* number of output bytes left to go */
        if (n >= SKEIN_512_BLOCK_BYTES)
            n  = SKEIN_512_BLOCK_BYTES;
        Skein_Put64_LSB_First(hashVal+i*SKEIN_512_BLOCK_BYTES,ctx->X,n);   /* "output" the ctr mode bytes */
        Skein_Show_Final(256,&ctx->h,n,hashVal+i*SKEIN_512_BLOCK_BYTES);
        memcpy(ctx->X,X,sizeof(X));   /* restore the counter mode key for next time */
        }
    return SKEIN_SUCCESS;
    }

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* just do the OUTPUT stage                                       */
static int Skein1024_Output(Skein1024_Ctxt_t *ctx, u08b_t *hashVal)
    {
    size_t i,n,byteCnt;
    u64b_t X[SKEIN1024_STATE_WORDS];
    Skein_Assert(ctx->h.bCnt <= SKEIN1024_BLOCK_BYTES,SKEIN_FAIL);    /* catch uninitialized context */

    /* now output the result */
    byteCnt = (ctx->h.hashBitLen + 7) >> 3;    /* total number of output bytes */

    /* run Threefish in "counter mode" to generate output */
    memset(ctx->b,0,sizeof(ctx->b));  /* zero out b[], so it can hold the counter */
    memcpy(X,ctx->X,sizeof(X));       /* keep a local copy of counter mode "key" */
    for (i=0;i*SKEIN1024_BLOCK_BYTES < byteCnt;i++)
        {
        ((u64b_t *)ctx->b)[0]= Skein_Swap64((u64b_t) i); /* build the counter block */
        Skein_Start_New_Type(ctx,OUT_FINAL);
        Skein1024_Process_Block(ctx,ctx->b,1,sizeof(u64b_t)); /* run "counter mode" */
        n = byteCnt - i*SKEIN1024_BLOCK_BYTES;   /* number of output bytes left to go */
        if (n >= SKEIN1024_BLOCK_BYTES)
            n  = SKEIN1024_BLOCK_BYTES;
        Skein_Put64_LSB_First(hashVal+i*SKEIN1024_BLOCK_BYTES,ctx->X,n);   /* "output" the ctr mode bytes */
        Skein_Show_Final(256,&ctx->h,n,hashVal+i*SKEIN1024_BLOCK_BYTES);
        memcpy(ctx->X,X,sizeof(X));   /* restore the counter mode key for next time */
        }
    return SKEIN_SUCCESS;
    }
#endif
#endif

typedef struct
{
  uint_t  statebits;                      /* 256, 512, or 1024 */
  union
  {
    Skein_Ctxt_Hdr_t h;                 /* common header "overlay" */
    Skein_256_Ctxt_t ctx_256;
    Skein_512_Ctxt_t ctx_512;
    Skein1024_Ctxt_t ctx1024;
  } u;
}
hashState;

/* "incremental" hashing API */
static HashReturn Init  (hashState *state, int hashbitlen);
static HashReturn Update(hashState *state, const BitSequence *data, DataLength databitlen);
static HashReturn Final (hashState *state,       BitSequence *hashval);

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* select the context size and init the context */
static HashReturn Init(hashState *state, int hashbitlen)
{
#if SKEIN_256_NIST_MAX_HASH_BITS
  if (hashbitlen <= SKEIN_256_NIST_MAX_HASHBITS)
  {
    Skein_Assert(hashbitlen > 0,BAD_HASHLEN);
    state->statebits = 64*SKEIN_256_STATE_WORDS;
    return Skein_256_Init(&state->u.ctx_256,(size_t) hashbitlen);
  }
#endif
  if (hashbitlen <= SKEIN_512_NIST_MAX_HASHBITS)
  {
    state->statebits = 64*SKEIN_512_STATE_WORDS;
    return Skein_512_Init(&state->u.ctx_512,(size_t) hashbitlen);
  }
  else
  {
    state->statebits = 64*SKEIN1024_STATE_WORDS;
    return Skein1024_Init(&state->u.ctx1024,(size_t) hashbitlen);
  }
}

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* process data to be hashed */
static HashReturn Update(hashState *state, const BitSequence *data, DataLength databitlen)
{
  /* only the final Update() call is allowed do partial bytes, else assert an error */
  Skein_Assert((state->u.h.T[1] & SKEIN_T1_FLAG_BIT_PAD) == 0 || databitlen == 0, SKEIN_FAIL);

  Skein_Assert(state->statebits % 256 == 0 && (state->statebits-256) < 1024,SKEIN_FAIL);
  if ((databitlen & 7) == 0)  /* partial bytes? */
  {
    switch ((state->statebits >> 8) & 3)
    {
    case 2:  return Skein_512_Update(&state->u.ctx_512,data,databitlen >> 3);
    case 1:  return Skein_256_Update(&state->u.ctx_256,data,databitlen >> 3);
    case 0:  return Skein1024_Update(&state->u.ctx1024,data,databitlen >> 3);
    default: return SKEIN_FAIL;
    }
  }
  else
  {   /* handle partial final byte */
    size_t bCnt = (databitlen >> 3) + 1;                  /* number of bytes to handle (nonzero here!) */
    u08b_t b,mask;

    mask = (u08b_t) (1u << (7 - (databitlen & 7)));       /* partial byte bit mask */
    b    = (u08b_t) ((data[bCnt-1] & (0-mask)) | mask);   /* apply bit padding on final byte */

    switch ((state->statebits >> 8) & 3)
    {
    case 2:  Skein_512_Update(&state->u.ctx_512,data,bCnt-1); /* process all but the final byte    */
      Skein_512_Update(&state->u.ctx_512,&b  ,  1   ); /* process the (masked) partial byte */
      break;
    case 1:  Skein_256_Update(&state->u.ctx_256,data,bCnt-1); /* process all but the final byte    */
      Skein_256_Update(&state->u.ctx_256,&b  ,  1   ); /* process the (masked) partial byte */
      break;
    case 0:  Skein1024_Update(&state->u.ctx1024,data,bCnt-1); /* process all but the final byte    */
      Skein1024_Update(&state->u.ctx1024,&b  ,  1   ); /* process the (masked) partial byte */
      break;
    default: return SKEIN_FAIL;
    }
    Skein_Set_Bit_Pad_Flag(state->u.h);                    /* set tweak flag for the final call */

    return SKEIN_SUCCESS;
  }
}

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* finalize hash computation and output the result (hashbitlen bits) */
static HashReturn Final(hashState *state, BitSequence *hashval)
{
  Skein_Assert(state->statebits % 256 == 0 && (state->statebits-256) < 1024,FAIL);
  switch ((state->statebits >> 8) & 3)
  {
  case 2:  return Skein_512_Final(&state->u.ctx_512,hashval);
  case 1:  return Skein_256_Final(&state->u.ctx_256,hashval);
  case 0:  return Skein1024_Final(&state->u.ctx1024,hashval);
  default: return SKEIN_FAIL;
  }
}

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
/* all-in-one hash function */
HashReturn skein_hash(int hashbitlen, const BitSequence *data, /* all-in-one call */
                DataLength databitlen,BitSequence *hashval)
{
  hashState  state;
  HashReturn r = Init(&state,hashbitlen);
  if (r == SKEIN_SUCCESS)
  { /* these calls do not fail when called properly */
    r = Update(&state,data,databitlen);
    Final(&state,hashval);
  }
  return r;
}