generic crc calculation code

Originally committed as revision 5115 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/utils.c

@@ -29,6 +29,7 @@
 #include "mpegvideo.h"
 #include "integer.h"
 #include "opt.h"
+#include "crc.h"
 #include <stdarg.h>
 #include <limits.h>
 #include <float.h>
@@ -1218,6 +1219,11 @@ unsigned avcodec_build( void )
   return LIBAVCODEC_BUILD;
 }
 
+static void init_crcs(void){
+    av_crc04C11DB7= av_mallocz_static(sizeof(AVCRC) * 257);
+    av_crc_init(av_crc04C11DB7, 0, 32, 0x04c11db7, sizeof(AVCRC)*257);
+}
+
 /* must be called before any other functions */
 void avcodec_init(void)
 {
@@ -1228,6 +1234,7 @@ void avcodec_init(void)
     inited = 1;
 
     dsputil_static_init();
+    init_crcs();
 }
 
 /**

libavformat/mpegts.c

@@ -17,7 +17,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 #include "avformat.h"
-
+#include "crc.h"
 #include "mpegts.h"
 
 //#define DEBUG_SI
@@ -146,7 +146,7 @@ static void write_section_data(AVFormatContext *s, MpegTSFilter *tss1,
     if (tss->section_h_size != -1 && tss->section_index >= tss->section_h_size) {
         tss->end_of_section_reached = 1;
         if (!tss->check_crc ||
-            mpegts_crc32(tss->section_buf, tss->section_h_size) == 0)
+            av_crc(av_crc04C11DB7, -1, tss->section_buf, tss->section_h_size) == 0)
             tss->section_cb(tss->opaque, tss->section_buf, tss->section_h_size);
     }
 }

libavformat/mpegtsenc.c

@@ -17,68 +17,11 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 #include "avformat.h"
-
+#include "crc.h"
 #include "mpegts.h"
 
 /* write DVB SI sections */
 
-static const uint32_t crc_table[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
-};
-
-unsigned int mpegts_crc32(const uint8_t *data, int len)
-{
-    register int i;
-    unsigned int crc = 0xffffffff;
-
-    for (i=0; i<len; i++)
-        crc = (crc << 8) ^ crc_table[((crc >> 24) ^ *data++) & 0xff];
-
-    return crc;
-}
-
 #ifdef CONFIG_MUXERS
 /*********************************************/
 /* mpegts section writer */
@@ -99,7 +42,7 @@ void mpegts_write_section(MpegTSSection *s, uint8_t *buf, int len)
     unsigned char *q;
     int first, b, len1, left;
 
-    crc = mpegts_crc32(buf, len - 4);
+    crc = bswap_32(av_crc(av_crc04C11DB7, -1, buf, len - 4));
     buf[len - 4] = (crc >> 24) & 0xff;
     buf[len - 3] = (crc >> 16) & 0xff;
     buf[len - 2] = (crc >> 8) & 0xff;

libavutil/Makefile

@@ -15,6 +15,7 @@ OBJS= mathematics.o \
       integer.o \
       rational.o \
       intfloat_readwrite.o \
+      crc.o \
 
 HEADERS = avutil.h common.h mathematics.h integer.h rational.h \
           intfloat_readwrite.h

libavutil/crc.c

+#include "common.h"
+#include "crc.h"
+
+AVCRC *av_crcEDB88320;
+AVCRC *av_crc04C11DB7;
+AVCRC *av_crc8005    ;
+AVCRC *av_crc07      ;
+
+/**
+ * Inits a crc table.
+ * @param ctx must be an array of sizeof(AVCRC)*257 or sizeof(AVCRC)*1024
+ * @param cts_size size of ctx in bytes
+ * @return <0 on failure
+ */
+int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size){
+    int i, j;
+    uint32_t c;
+
+    if (bits < 8 || bits > 32 || poly >= (1LL<<bits))
+        return -1;
+    if (ctx_size != sizeof(AVCRC)*257 && ctx_size != sizeof(AVCRC)*1024)
+        return -1;
+
+    for (i = 0; i < 256; i++) {
+        if (le) {
+            for (c = i, j = 0; j < 8; j++)
+                c = (c>>1)^(poly & (-(c&1)));
+            ctx[i] = c;
+        } else {
+            for (c = i << 24, j = 0; j < 8; j++)
+                c = (c<<1) ^ ((poly<<(32-bits)) & (((int32_t)c)>>31) );
+            ctx[i] = bswap_32(c);
+        }
+    }
+    ctx[256]=1;
+    if(ctx_size >= sizeof(AVCRC)*1024)
+        for (i = 0; i < 256; i++)
+            for(j=0; j<3; j++)
+                ctx[256*(j+1) + i]= (ctx[256*j + i]>>8) ^ ctx[ ctx[256*j + i]&0xFF ];
+
+    return 0;
+}
+
+uint32_t av_crc(const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length){
+    const uint8_t *end= buffer+length;
+
+    if(!ctx[256])
+        while(buffer<end-3){
+            crc ^= le2me_32(*(uint32_t*)buffer); buffer+=4;
+            crc =  ctx[3*256 + ( crc     &0xFF)]
+                  ^ctx[2*256 + ((crc>>8 )&0xFF)]
+                  ^ctx[1*256 + ((crc>>16)&0xFF)]
+                  ^ctx[0*256 + ((crc>>24)     )];
+        }
+    while(buffer<end)
+        crc = ctx[((uint8_t)crc) ^ *buffer++] ^ (crc >> 8);
+
+    return crc;
+}
+
+#ifdef TEST
+#undef printf
+main(){
+    uint8_t buf[1999];
+    int i;
+    int p[4][4]={{1, 32, 0xedb88320L, 0x3D5CDD04},
+                 {0, 32, 0x04c11db7L, 0xC0F5BAE0},
+                 {0, 16, 0x8005     , 0x1FBB    },
+                 {0,  8, 0x07       , 0xE3      },};
+    AVCRC ctx[1 ? 1024:257];
+
+    for(i=0; i<sizeof(buf); i++)
+        buf[i]= i+i*i;
+
+    for(i=0; i<4; i++){
+        av_crc_init(ctx, p[i][0], p[i][1], p[i][2], sizeof(ctx));
+        printf("crc %08X =%X\n", p[i][2], av_crc(ctx, 0, buf, sizeof(buf)));
+    }
+}
+#endif

libavutil/crc.h

+#ifndef CRC_H
+#define CRC_H
+
+typedef uint32_t AVCRC;
+
+extern AVCRC *av_crcEDB88320;
+extern AVCRC *av_crc04C11DB7;
+extern AVCRC *av_crc8005    ;
+extern AVCRC *av_crc07      ;
+
+int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size);
+uint32_t av_crc(const AVCRC *ctx, uint32_t start_crc, const uint8_t *buffer, size_t length);
+
+#endif /* CRC_H */
+