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-rw-r--r--src/liblzma/lzma/lzma_decoder.c42
-rw-r--r--src/liblzma/rangecoder/range_decoder.h87
2 files changed, 66 insertions, 63 deletions
diff --git a/src/liblzma/lzma/lzma_decoder.c b/src/liblzma/lzma/lzma_decoder.c
index 6e2c166d..dda94177 100644
--- a/src/liblzma/lzma/lzma_decoder.c
+++ b/src/liblzma/lzma/lzma_decoder.c
@@ -151,10 +151,6 @@ struct lzma_coder_s {
/// Length of a repeated match.
lzma_length_decoder rep_match_len_decoder;
-
- /// The first five bytes of LZMA compressed data are treated
- /// specially. Once they are read, this stays at zero.
- size_t init_bytes_left;
};
@@ -166,7 +162,7 @@ struct lzma_coder_s {
static bool lzma_attribute((pure))
decode_dummy(const lzma_coder *restrict coder,
const uint8_t *restrict in, size_t in_pos_local,
- const size_t in_size, uint32_t rc_range, uint32_t rc_code,
+ const size_t in_size, lzma_range_decoder rc,
uint32_t state, uint32_t rep0, const uint32_t now_pos)
{
uint32_t rc_bound;
@@ -268,20 +264,11 @@ decode_dummy(const lzma_coder *restrict coder,
coder->pos_decoders + offset,
direct_bits);
} else {
- // Decode direct bits
assert(pos_slot >= 14);
assert(direct_bits >= 6);
direct_bits -= ALIGN_BITS;
assert(direct_bits >= 2);
- do {
- rc_normalize();
- rc_range >>= 1;
- const uint32_t t
- = (rc_code - rc_range)
- >> 31;
- rc_code -= rc_range & (t - 1);
- } while (--direct_bits > 0);
- rep0 <<= ALIGN_BITS;
+ rc_decode_direct_dummy(direct_bits);
bittree_reverse_decode_dummy(
coder->pos_align_decoder,
@@ -342,15 +329,8 @@ decode_real(lzma_coder *restrict coder, const uint8_t *restrict in,
// Initialization //
////////////////////
- while (coder->init_bytes_left > 0) {
- if (*in_pos == in_size)
- return false;
-
- coder->rc.code = (coder->rc.code << 8) | in[*in_pos];
- ++*in_pos;
- --coder->init_bytes_left;
- }
-
+ if (!rc_read_init(&coder->rc, in, in_pos, in_size))
+ return false;
///////////////
// Variables //
@@ -386,7 +366,7 @@ decode_real(lzma_coder *restrict coder, const uint8_t *restrict in,
while (coder->lz.pos < coder->lz.limit && (in_pos_local < in_limit
|| (has_safe_buffer && decode_dummy(
coder, in, in_pos_local, in_size,
- rc_range, rc_code, state, rep0, now_pos)))) {
+ rc, state, rep0, now_pos)))) {
/////////////////////
// Actual decoding //
@@ -513,20 +493,11 @@ decode_real(lzma_coder *restrict coder, const uint8_t *restrict in,
coder->pos_decoders + offset,
direct_bits);
} else {
- // Decode direct bits
assert(pos_slot >= 14);
assert(direct_bits >= 6);
direct_bits -= ALIGN_BITS;
assert(direct_bits >= 2);
- do {
- rc_normalize();
- rc_range >>= 1;
- const uint32_t t
- = (rc_code - rc_range)
- >> 31;
- rc_code -= rc_range & (t - 1);
- rep0 = (rep0 << 1) | (1 - t);
- } while (--direct_bits > 0);
+ rc_decode_direct(rep0, direct_bits);
rep0 <<= ALIGN_BITS;
bittree_reverse_decode(rep0,
@@ -762,7 +733,6 @@ lzma_lzma_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
next->coder->pos_bits = options->pos_bits;
next->coder->pos_mask = (1 << next->coder->pos_bits) - 1;
next->coder->now_pos = 0;
- next->coder->init_bytes_left = 5;
// Range decoder
rc_reset(next->coder->rc);
diff --git a/src/liblzma/rangecoder/range_decoder.h b/src/liblzma/rangecoder/range_decoder.h
index 0583faaf..f3dcc84e 100644
--- a/src/liblzma/rangecoder/range_decoder.h
+++ b/src/liblzma/rangecoder/range_decoder.h
@@ -27,36 +27,50 @@
typedef struct {
uint32_t range;
uint32_t code;
+ uint32_t init_bytes_left;
} lzma_range_decoder;
+static inline bool
+rc_read_init(lzma_range_decoder *rc, const uint8_t *restrict in,
+ size_t *restrict in_pos, size_t in_size)
+{
+ while (rc->init_bytes_left > 0) {
+ if (*in_pos == in_size)
+ return false;
+
+ rc->code = (rc->code << 8) | in[*in_pos];
+ ++*in_pos;
+ --rc->init_bytes_left;
+ }
+
+ return true;
+}
+
+
/// Makes local copies of range decoder variables.
-#define rc_to_local(rc) \
- uint32_t rc_range = (rc).range; \
- uint32_t rc_code = (rc).code; \
+#define rc_to_local(range_decoder) \
+ lzma_range_decoder rc = range_decoder; \
uint32_t rc_bound
/// Stores the local copes back to the range decoder structure.
-#define rc_from_local(rc) \
-do {\
- (rc).range = rc_range; \
- (rc).code = rc_code; \
-} while (0)
+#define rc_from_local(range_decoder) \
+ range_decoder = rc
/// Resets the range decoder structure.
-#define rc_reset(rc) \
+#define rc_reset(range_decoder) \
do { \
- (rc).range = UINT32_MAX; \
- (rc).code = 0; \
+ (range_decoder).range = UINT32_MAX; \
+ (range_decoder).code = 0; \
+ (range_decoder).init_bytes_left = 5; \
} while (0)
// All of the macros in this file expect the following variables being defined:
-// - uint32_t rc_range;
-// - uint32_t rc_code;
+// - lzma_range_decoder range_decoder;
// - uint32_t rc_bound; // Temporary variable
-// - uint8_t *in;
-// - size_t in_pos_local; // Local alias for *in_pos
+// - uint8_t *in;
+// - size_t in_pos_local; // Local alias for *in_pos
//////////////////
@@ -66,9 +80,9 @@ do { \
// Read the next byte of compressed data from buffer_in, if needed.
#define rc_normalize() \
do { \
- if (rc_range < TOP_VALUE) { \
- rc_range <<= SHIFT_BITS; \
- rc_code = (rc_code << SHIFT_BITS) | in[in_pos_local++]; \
+ if (rc.range < TOP_VALUE) { \
+ rc.range <<= SHIFT_BITS; \
+ rc.code = (rc.code << SHIFT_BITS) | in[in_pos_local++]; \
} \
} while (0)
@@ -88,37 +102,56 @@ do { \
#define if_bit_0(prob) \
rc_normalize(); \
- rc_bound = (rc_range >> BIT_MODEL_TOTAL_BITS) * (prob); \
- if (rc_code < rc_bound)
+ rc_bound = (rc.range >> BIT_MODEL_TOTAL_BITS) * (prob); \
+ if (rc.code < rc_bound)
#define update_bit_0(prob) \
do { \
- rc_range = rc_bound; \
+ rc.range = rc_bound; \
prob += (BIT_MODEL_TOTAL - (prob)) >> MOVE_BITS; \
} while (0)
#define update_bit_1(prob) \
do { \
- rc_range -= rc_bound; \
- rc_code -= rc_bound; \
+ rc.range -= rc_bound; \
+ rc.code -= rc_bound; \
prob -= (prob) >> MOVE_BITS; \
} while (0)
-// Dummy versions don't update prob.
+#define rc_decode_direct(dest, count) \
+do { \
+ rc_normalize(); \
+ rc.range >>= 1; \
+ rc_bound = (rc.code - rc.range) >> 31; \
+ rc.code -= rc.range & (rc_bound - 1); \
+ dest = ((dest) << 1) | (1 - rc_bound);\
+} while (--count > 0)
+
+
+// Dummy versions don't update prob or dest.
#define update_bit_0_dummy() \
- rc_range = rc_bound
+ rc.range = rc_bound
#define update_bit_1_dummy() \
do { \
- rc_range -= rc_bound; \
- rc_code -= rc_bound; \
+ rc.range -= rc_bound; \
+ rc.code -= rc_bound; \
} while (0)
+#define rc_decode_direct_dummy(count) \
+do { \
+ rc_normalize(); \
+ rc.range >>= 1; \
+ rc_bound = (rc.code - rc.range) >> 31; \
+ rc.code -= rc.range & (rc_bound - 1); \
+} while (--count > 0)
+
+
///////////////////////
// Bit tree decoding //
///////////////////////
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-27 08:00:58 +0000