Put the interesting parts of XZ Utils into the public domain.

Some minor documentation cleanups were made at the same time.

15 files changed, 88 insertions, 93 deletions

diff --git a/src/liblzma/check/Makefile.am b/src/liblzma/check/Makefile.am
index 74011695..1409bec0 100644
--- a/src/liblzma/check/Makefile.am
+++ b/src/liblzma/check/Makefile.am
@@ -1,10 +1,8 @@
 ##
-##  This code has been put into the public domain.
+## Author: Lasse Collin
 ##
-##  This library is distributed in the hope that it will be useful,
-##  but WITHOUT ANY WARRANTY; without even the implied warranty of
-##  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-##  Lesser General Public License for more details.
+## This file has been put into the public domain.
+## You can do whatever you want with this file.
 ##
 
 EXTRA_DIST = crc32_tablegen.c crc64_tablegen.c
diff --git a/src/liblzma/check/check.c b/src/liblzma/check/check.c
index 484be594..ba8622e6 100644
--- a/src/liblzma/check/check.c
+++ b/src/liblzma/check/check.c
@@ -3,11 +3,10 @@
 /// \file       check.c
 /// \brief      Single API to access different integrity checks
 //
-//  This code has been put into the public domain.
+//  Author:     Lasse Collin
 //
-//  This library is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/src/liblzma/check/check.h b/src/liblzma/check/check.h
index 1dfc4d73..e100d2b8 100644
--- a/src/liblzma/check/check.h
+++ b/src/liblzma/check/check.h
@@ -3,11 +3,10 @@
 /// \file       check.h
 /// \brief      Internal API to different integrity check functions
 //
-//  This code has been put into the public domain.
+//  Author:     Lasse Collin
 //
-//  This library is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/src/liblzma/check/crc32_fast.c b/src/liblzma/check/crc32_fast.c
index 61eacd61..a308eff5 100644
--- a/src/liblzma/check/crc32_fast.c
+++ b/src/liblzma/check/crc32_fast.c
@@ -2,12 +2,17 @@
 //
 /// \file       crc32.c
 /// \brief      CRC32 calculation
+///
+/// Calculate the CRC32 using the slice-by-eight algorithm.
+/// It is explained in this document:
+/// http://www.intel.com/technology/comms/perfnet/download/CRC_generators.pdf
+/// The code in this file is not the same as in Intel's paper, but
+/// the basic principle is identical.
 //
-//  This code has been put into the public domain.
+//  Author:     Lasse Collin
 //
-//  This library is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////
 
@@ -43,17 +48,6 @@ lzma_crc32(const uint8_t *buf, size_t size, uint32_t crc)
 		size &= (size_t)(7);
 
 		// Calculate the CRC32 using the slice-by-eight algorithm.
-		// It is explained in this document:
-		// http://www.intel.com/technology/comms/perfnet/download/CRC_generators.pdf
-		//
-		// The code below is different than the code in Intel's
-		// paper, but the principle is identical. This should be
-		// faster with GCC than Intel's code. This is tested only
-		// with GCC 3.4.6 and 4.1.2 on x86, so your results may vary.
-		//
-		// Using -Os and -fomit-frame-pointer seem to give the best
-		// results at least with GCC 4.1.2 on x86. It's sill far
-		// from the speed of hand-optimized assembler.
 		while (buf < limit) {
 			crc ^= *(uint32_t *)(buf);
 			buf += 4;
@@ -66,9 +60,9 @@ lzma_crc32(const uint8_t *buf, size_t size, uint32_t crc)
 			const uint32_t tmp = *(uint32_t *)(buf);
 			buf += 4;
 
-			// It is critical for performance, that
-			// the crc variable is XORed between the
-			// two table-lookup pairs.
+			// At least with some compilers, it is critical for
+			// performance, that the crc variable is XORed
+			// between the two table-lookup pairs.
 			crc = lzma_crc32_table[3][A(tmp)]
 			    ^ lzma_crc32_table[2][B(tmp)]
 			    ^ crc
diff --git a/src/liblzma/check/crc32_small.c b/src/liblzma/check/crc32_small.c
index 8507436b..5f8a3286 100644
--- a/src/liblzma/check/crc32_small.c
+++ b/src/liblzma/check/crc32_small.c
@@ -3,11 +3,10 @@
 /// \file       crc32_small.c
 /// \brief      CRC32 calculation (size-optimized)
 //
-//  This code has been put into the public domain.
+//  Author:     Lasse Collin
 //
-//  This library is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/src/liblzma/check/crc32_table.c b/src/liblzma/check/crc32_table.c
index 4fcebc2b..368874eb 100644
--- a/src/liblzma/check/crc32_table.c
+++ b/src/liblzma/check/crc32_table.c
@@ -3,11 +3,10 @@
 /// \file       crc32_table.c
 /// \brief      Precalculated CRC32 table with correct endianness
 //
-//  This code has been put into the public domain.
+//  Author:     Lasse Collin
 //
-//  This library is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/src/liblzma/check/crc32_tablegen.c b/src/liblzma/check/crc32_tablegen.c
index fbcbf474..0cbfecd8 100644
--- a/src/liblzma/check/crc32_tablegen.c
+++ b/src/liblzma/check/crc32_tablegen.c
@@ -6,11 +6,10 @@
 /// Compiling: gcc -std=c99 -o crc32_tablegen crc32_tablegen.c
 /// Add -DWORDS_BIGENDIAN to generate big endian table.
 //
-//  This code has been put into the public domain.
+//  Author:     Lasse Collin
 //
-//  This library is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/src/liblzma/check/crc32_x86.S b/src/liblzma/check/crc32_x86.S
index ec28cf5d..b3c7538f 100644
--- a/src/liblzma/check/crc32_x86.S
+++ b/src/liblzma/check/crc32_x86.S
@@ -1,11 +1,18 @@
 /*
  * Speed-optimized CRC32 using slicing-by-eight algorithm
- * Instruction set: i386
- * Optimized for:   i686
  *
- * This code has been put into the public domain by its authors:
- * Original code by Igor Pavlov <http://7-zip.org/>
- * Position-independent version by Lasse Collin <lasse.collin@tukaani.org>
+ * This uses only i386 instructions, but it is optimized for i686 and later
+ * (including e.g. Pentium II/III/IV, Athlon XP, and Core 2). For i586
+ * (e.g. Pentium), slicing-by-four would be better, and even the C version
+ * of slicing-by-eight built with gcc -march=i586 tends to be a little bit
+ * better than this. Very few probably run this code on i586 or older x86
+ * so this shouldn't be a problem in practice.
+ *
+ * Authors: Igor Pavlov (original version)
+ *          Lasse Collin (AT&T syntax, PIC support, better portability)
+ *
+ * This file has been put into the public domain.
+ * You can do whatever you want with this file.
  *
  * This code needs lzma_crc32_table, which can be created using the
  * following C code:
@@ -15,10 +22,10 @@ uint32_t lzma_crc32_table[8][256];
 void
 init_table(void)
 {
-	// IEEE-802.3 (CRC32)
+	// IEEE-802.3
 	static const uint32_t poly32 = UINT32_C(0xEDB88320);
 
-	// Castagnoli (CRC32C)
+	// Castagnoli
 	// static const uint32_t poly32 = UINT32_C(0x82F63B78);
 
 	// Koopman
diff --git a/src/liblzma/check/crc64_fast.c b/src/liblzma/check/crc64_fast.c
index d2d1d60f..25557264 100644
--- a/src/liblzma/check/crc64_fast.c
+++ b/src/liblzma/check/crc64_fast.c
@@ -2,12 +2,15 @@
 //
 /// \file       crc64.c
 /// \brief      CRC64 calculation
+///
+/// Calculate the CRC64 using the slice-by-four algorithm. This is the same
+/// idea that is used in crc32_fast.c, but for CRC64 we use only four tables
+/// instead of eight to avoid increasing CPU cache usage.
 //
-//  This code has been put into the public domain.
+//  Author:     Lasse Collin
 //
-//  This library is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////
 
@@ -22,7 +25,7 @@
 #endif
 
 
-// See comments in crc32.c.
+// See the comments in crc32_fast.c. They aren't duplicated here.
 extern LZMA_API(uint64_t)
 lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
 {
@@ -41,10 +44,6 @@ lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
 		const uint8_t *const limit = buf + (size & ~(size_t)(3));
 		size &= (size_t)(3);
 
-		// Calculate the CRC64 using the slice-by-four algorithm.
-		//
-		// In contrast to CRC32 code, this one seems to be fastest
-		// with -O3 -fomit-frame-pointer.
 		while (buf < limit) {
 #ifdef WORDS_BIGENDIAN
 			const uint32_t tmp = (crc >> 32) ^ *(uint32_t *)(buf);
@@ -53,9 +52,6 @@ lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
 #endif
 			buf += 4;
 
-			// It is critical for performance, that
-			// the crc variable is XORed between the
-			// two table-lookup pairs.
 			crc = lzma_crc64_table[3][A(tmp)]
 			    ^ lzma_crc64_table[2][B(tmp)]
 			    ^ S32(crc)
diff --git a/src/liblzma/check/crc64_small.c b/src/liblzma/check/crc64_small.c
index 26b04997..55d72316 100644
--- a/src/liblzma/check/crc64_small.c
+++ b/src/liblzma/check/crc64_small.c
@@ -3,11 +3,10 @@
 /// \file       crc64_small.c
 /// \brief      CRC64 calculation (size-optimized)
 //
-//  This code has been put into the public domain.
+//  Author:     Lasse Collin
 //
-//  This library is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/src/liblzma/check/crc64_table.c b/src/liblzma/check/crc64_table.c
index 983ed31f..1fbcd947 100644
--- a/src/liblzma/check/crc64_table.c
+++ b/src/liblzma/check/crc64_table.c
@@ -3,11 +3,10 @@
 /// \file       crc64_table.c
 /// \brief      Precalculated CRC64 table with correct endianness
 //
-//  This code has been put into the public domain.
+//  Author:     Lasse Collin
 //
-//  This library is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/src/liblzma/check/crc64_tablegen.c b/src/liblzma/check/crc64_tablegen.c
index a0fa4ab2..92b9a7da 100644
--- a/src/liblzma/check/crc64_tablegen.c
+++ b/src/liblzma/check/crc64_tablegen.c
@@ -6,11 +6,10 @@
 /// Compiling: gcc -std=c99 -o crc64_tablegen crc64_tablegen.c
 /// Add -DWORDS_BIGENDIAN to generate big endian table.
 //
-//  This code has been put into the public domain.
+//  Author:     Lasse Collin
 //
-//  This library is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/src/liblzma/check/crc64_x86.S b/src/liblzma/check/crc64_x86.S
index 3c25d42d..5e170bc8 100644
--- a/src/liblzma/check/crc64_x86.S
+++ b/src/liblzma/check/crc64_x86.S
@@ -1,11 +1,14 @@
 /*
  * Speed-optimized CRC64 using slicing-by-four algorithm
- * Instruction set: i386
- * Optimized for:   i686
  *
- * This code has been put into the public domain by its authors:
- * Igor Pavlov <http://7-zip.org/>
- * Lasse Collin <lasse.collin@tukaani.org>
+ * This uses only i386 instructions, but it is optimized for i686 and later
+ * (including e.g. Pentium II/III/IV, Athlon XP, and Core 2).
+ *
+ * Authors: Igor Pavlov (original CRC32 assembly code)
+ *          Lasse Collin (CRC64 adaptation of the modified CRC32 code)
+ *
+ * This file has been put into the public domain.
+ * You can do whatever you want with this file.
  *
  * This code needs lzma_crc64_table, which can be created using the
  * following C code:
@@ -15,6 +18,7 @@ uint64_t lzma_crc64_table[4][256];
 void
 init_table(void)
 {
+	// ECMA-182
 	static const uint64_t poly64 = UINT64_C(0xC96C5795D7870F42);
 
 	for (size_t s = 0; s < 4; ++s) {
diff --git a/src/liblzma/check/crc_macros.h b/src/liblzma/check/crc_macros.h
index e827d07d..9e2c0303 100644
--- a/src/liblzma/check/crc_macros.h
+++ b/src/liblzma/check/crc_macros.h
@@ -1,13 +1,12 @@
 ///////////////////////////////////////////////////////////////////////////////
 //
-/// \file       crc_macros
+/// \file       crc_macros.h
 /// \brief      Some endian-dependent macros for CRC32 and CRC64
 //
-//  This code has been put into the public domain.
+//  Author:     Lasse Collin
 //
-//  This library is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/src/liblzma/check/sha256.c b/src/liblzma/check/sha256.c
index 9f90f7e7..978fc668 100644
--- a/src/liblzma/check/sha256.c
+++ b/src/liblzma/check/sha256.c
@@ -1,19 +1,24 @@
 ///////////////////////////////////////////////////////////////////////////////
 //
 /// \file       sha256.c
-/// \brief      SHA256
-//
-//  Based on the public domain code found from Wei Dai's Crypto++ library
-//  version 5.5.1: http://www.cryptopp.com/
-//  This code has been put into the public domain.
-//
+/// \brief      SHA-256
+///
 /// \todo       Crypto++ has x86 ASM optimizations. They use SSE so if they
 ///             are imported to liblzma, SSE instructions need to be used
 ///             conditionally to keep the code working on older boxes.
+///             We could also support using some external libary for SHA-256.
+//
+//  This code is based on the code found from 7-Zip, which has a modified
+//  version of the SHA-256 found from Crypto++ <http://www.cryptopp.com/>.
+//  The code was modified a little to fit into liblzma.
+//
+//  Authors:    Kevin Springle
+//              Wei Dai
+//              Igor Pavlov
+//              Lasse Collin
 //
-//  This library is distributed in the hope that it will be useful,
-//  but WITHOUT ANY WARRANTY; without even the implied warranty of
-//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
 //
 ///////////////////////////////////////////////////////////////////////////////