Switch to slicing-by-8 CRC32 algorithm.

src/Makefile.am

@@ -4,7 +4,7 @@ AM_CPPFLAGS = -I$(top_srcdir)/include -I$(top_builddir)/include
 
 lib_LTLIBRARIES = libogg.la
 
-libogg_la_SOURCES = framing.c bitwise.c
+libogg_la_SOURCES = framing.c bitwise.c crctable.h
 libogg_la_LDFLAGS = -no-undefined -version-info @LIB_CURRENT@:@LIB_REVISION@:@LIB_AGE@
 
 # build and run the self tests on 'make check'
@@ -14,7 +14,7 @@ noinst_PROGRAMS = test_bitwise test_framing
 test_bitwise_SOURCES = bitwise.c
 test_bitwise_CFLAGS = -D_V_SELFTEST
 
-test_framing_SOURCES = framing.c
+test_framing_SOURCES = framing.c crctable.h
 test_framing_CFLAGS = -D_V_SELFTEST
 
 check: $(noinst_PROGRAMS)

src/framing.c

@@ -5,7 +5,7 @@
  * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
  * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
  *                                                                  *
- * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2010             *
+ * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2018             *
  * by the Xiph.Org Foundation http://www.xiph.org/                  *
  *                                                                  *
  ********************************************************************
@@ -102,90 +102,31 @@ int ogg_page_packets(const ogg_page *og){
 
 #if 0
 /* helper to initialize lookup for direct-table CRC (illustrative; we
-   use the static init below) */
-
-static ogg_uint32_t _ogg_crc_entry(unsigned long index){
-  int           i;
-  unsigned long r;
-
-  r = index << 24;
-  for (i=0; i<8; i++)
-    if (r & 0x80000000UL)
-      r = (r << 1) ^ 0x04c11db7; /* The same as the ethernet generator
-                                    polynomial, although we use an
-                                    unreflected alg and an init/final
-                                    of 0, not 0xffffffff */
-    else
-       r<<=1;
- return (r & 0xffffffffUL);
+   use the static init in crctable.h) */
+
+static void _ogg_crc_init(){
+  int i, j;
+  ogg_uint32_t polynomial, crc;
+  polynomial = 0x04c11db7; /* The same as the ethernet generator
+                              polynomial, although we use an
+                              unreflected alg and an init/final
+                              of 0, not 0xffffffff */
+  for (i = 0; i <= 0xFF; i++){
+    crc = i << 24;
+
+    for (j = 0; j < 8; j++)
+      crc = (crc << 1) ^ (crc & (1 << 31) ? polynomial : 0);
+
+    crc_lookup[0][i] = crc;
+  }
+
+  for (i = 0; i <= 0xFF; i++)
+    for (j = 1; j < 8; j++)
+      crc_lookup[j][i] = crc_lookup[0][(crc_lookup[j - 1][i] >> 24) & 0xFF] ^ (crc_lookup[j - 1][i] << 8);
 }
 #endif
 
-static const ogg_uint32_t crc_lookup[256]={
-  0x00000000,0x04c11db7,0x09823b6e,0x0d4326d9,
-  0x130476dc,0x17c56b6b,0x1a864db2,0x1e475005,
-  0x2608edb8,0x22c9f00f,0x2f8ad6d6,0x2b4bcb61,
-  0x350c9b64,0x31cd86d3,0x3c8ea00a,0x384fbdbd,
-  0x4c11db70,0x48d0c6c7,0x4593e01e,0x4152fda9,
-  0x5f15adac,0x5bd4b01b,0x569796c2,0x52568b75,
-  0x6a1936c8,0x6ed82b7f,0x639b0da6,0x675a1011,
-  0x791d4014,0x7ddc5da3,0x709f7b7a,0x745e66cd,
-  0x9823b6e0,0x9ce2ab57,0x91a18d8e,0x95609039,
-  0x8b27c03c,0x8fe6dd8b,0x82a5fb52,0x8664e6e5,
-  0xbe2b5b58,0xbaea46ef,0xb7a96036,0xb3687d81,
-  0xad2f2d84,0xa9ee3033,0xa4ad16ea,0xa06c0b5d,
-  0xd4326d90,0xd0f37027,0xddb056fe,0xd9714b49,
-  0xc7361b4c,0xc3f706fb,0xceb42022,0xca753d95,
-  0xf23a8028,0xf6fb9d9f,0xfbb8bb46,0xff79a6f1,
-  0xe13ef6f4,0xe5ffeb43,0xe8bccd9a,0xec7dd02d,
-  0x34867077,0x30476dc0,0x3d044b19,0x39c556ae,
-  0x278206ab,0x23431b1c,0x2e003dc5,0x2ac12072,
-  0x128e9dcf,0x164f8078,0x1b0ca6a1,0x1fcdbb16,
-  0x018aeb13,0x054bf6a4,0x0808d07d,0x0cc9cdca,
-  0x7897ab07,0x7c56b6b0,0x71159069,0x75d48dde,
-  0x6b93dddb,0x6f52c06c,0x6211e6b5,0x66d0fb02,
-  0x5e9f46bf,0x5a5e5b08,0x571d7dd1,0x53dc6066,
-  0x4d9b3063,0x495a2dd4,0x44190b0d,0x40d816ba,
-  0xaca5c697,0xa864db20,0xa527fdf9,0xa1e6e04e,
-  0xbfa1b04b,0xbb60adfc,0xb6238b25,0xb2e29692,
-  0x8aad2b2f,0x8e6c3698,0x832f1041,0x87ee0df6,
-  0x99a95df3,0x9d684044,0x902b669d,0x94ea7b2a,
-  0xe0b41de7,0xe4750050,0xe9362689,0xedf73b3e,
-  0xf3b06b3b,0xf771768c,0xfa325055,0xfef34de2,
-  0xc6bcf05f,0xc27dede8,0xcf3ecb31,0xcbffd686,
-  0xd5b88683,0xd1799b34,0xdc3abded,0xd8fba05a,
-  0x690ce0ee,0x6dcdfd59,0x608edb80,0x644fc637,
-  0x7a089632,0x7ec98b85,0x738aad5c,0x774bb0eb,
-  0x4f040d56,0x4bc510e1,0x46863638,0x42472b8f,
-  0x5c007b8a,0x58c1663d,0x558240e4,0x51435d53,
-  0x251d3b9e,0x21dc2629,0x2c9f00f0,0x285e1d47,
-  0x36194d42,0x32d850f5,0x3f9b762c,0x3b5a6b9b,
-  0x0315d626,0x07d4cb91,0x0a97ed48,0x0e56f0ff,
-  0x1011a0fa,0x14d0bd4d,0x19939b94,0x1d528623,
-  0xf12f560e,0xf5ee4bb9,0xf8ad6d60,0xfc6c70d7,
-  0xe22b20d2,0xe6ea3d65,0xeba91bbc,0xef68060b,
-  0xd727bbb6,0xd3e6a601,0xdea580d8,0xda649d6f,
-  0xc423cd6a,0xc0e2d0dd,0xcda1f604,0xc960ebb3,
-  0xbd3e8d7e,0xb9ff90c9,0xb4bcb610,0xb07daba7,
-  0xae3afba2,0xaafbe615,0xa7b8c0cc,0xa379dd7b,
-  0x9b3660c6,0x9ff77d71,0x92b45ba8,0x9675461f,
-  0x8832161a,0x8cf30bad,0x81b02d74,0x857130c3,
-  0x5d8a9099,0x594b8d2e,0x5408abf7,0x50c9b640,
-  0x4e8ee645,0x4a4ffbf2,0x470cdd2b,0x43cdc09c,
-  0x7b827d21,0x7f436096,0x7200464f,0x76c15bf8,
-  0x68860bfd,0x6c47164a,0x61043093,0x65c52d24,
-  0x119b4be9,0x155a565e,0x18197087,0x1cd86d30,
-  0x029f3d35,0x065e2082,0x0b1d065b,0x0fdc1bec,
-  0x3793a651,0x3352bbe6,0x3e119d3f,0x3ad08088,
-  0x2497d08d,0x2056cd3a,0x2d15ebe3,0x29d4f654,
-  0xc5a92679,0xc1683bce,0xcc2b1d17,0xc8ea00a0,
-  0xd6ad50a5,0xd26c4d12,0xdf2f6bcb,0xdbee767c,
-  0xe3a1cbc1,0xe760d676,0xea23f0af,0xeee2ed18,
-  0xf0a5bd1d,0xf464a0aa,0xf9278673,0xfde69bc4,
-  0x89b8fd09,0x8d79e0be,0x803ac667,0x84fbdbd0,
-  0x9abc8bd5,0x9e7d9662,0x933eb0bb,0x97ffad0c,
-  0xafb010b1,0xab710d06,0xa6322bdf,0xa2f33668,
-  0xbcb4666d,0xb8757bda,0xb5365d03,0xb1f740b4};
+#include "crctable.h"
 
 /* init the encode/decode logical stream state */
 
@@ -293,10 +234,27 @@ static int _os_lacing_expand(ogg_stream_state *os,long needed){
 /* Direct table CRC; note that this will be faster in the future if we
    perform the checksum simultaneously with other copies */
 
+static ogg_uint32_t _os_update_crc(ogg_uint32_t crc, unsigned char *buffer, int size){
+  while (size>=8){
+    crc^=buffer[0]<<24|buffer[1]<<16|buffer[2]<<8|buffer[3];
+
+    crc=crc_lookup[7][ crc>>24      ]^crc_lookup[6][(crc>>16)&0xFF]^
+        crc_lookup[5][(crc>> 8)&0xFF]^crc_lookup[4][ crc     &0xFF]^
+        crc_lookup[3][buffer[4]     ]^crc_lookup[2][buffer[5]     ]^
+        crc_lookup[1][buffer[6]     ]^crc_lookup[0][buffer[7]     ];
+
+    buffer+=8;
+    size-=8;
+  }
+
+  while (size--)
+    crc=(crc<<8)^crc_lookup[0][((crc >> 24)&0xff)^*buffer++];
+  return crc;
+}
+
 void ogg_page_checksum_set(ogg_page *og){
   if(og){
     ogg_uint32_t crc_reg=0;
-    int i;
 
     /* safety; needed for API behavior, but not framing code */
     og->header[22]=0;
@@ -304,10 +262,8 @@ void ogg_page_checksum_set(ogg_page *og){
     og->header[24]=0;
     og->header[25]=0;
 
-    for(i=0;i<og->header_len;i++)
-      crc_reg=(crc_reg<<8)^crc_lookup[((crc_reg >> 24)&0xff)^og->header[i]];
-    for(i=0;i<og->body_len;i++)
-      crc_reg=(crc_reg<<8)^crc_lookup[((crc_reg >> 24)&0xff)^og->body[i]];
+    crc_reg=_os_update_crc(crc_reg,og->header,og->header_len);
+    crc_reg=_os_update_crc(crc_reg,og->body,og->body_len);
 
     og->header[22]=(unsigned char)(crc_reg&0xff);
     og->header[23]=(unsigned char)((crc_reg>>8)&0xff);