/*
* copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
*
- * This file is part of FFmpeg.
+ * This file is part of Libav.
*
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
- * FFmpeg is distributed in the hope that it will be useful,
+ * Libav 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.
*
* You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
+ * License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
+#include "config.h"
#include "common.h"
+#include "bswap.h"
#include "crc.h"
-#if LIBAVUTIL_VERSION_INT < (50<<16)
-AVCRC *av_crcEDB88320;
-AVCRC *av_crc04C11DB7;
-AVCRC *av_crc8005 ;
-AVCRC *av_crc07 ;
+#if CONFIG_HARDCODED_TABLES
+#include "crc_data.h"
#else
-AVCRC av_crcEDB88320[257];
-AVCRC av_crc04C11DB7[257];
-AVCRC av_crc8005 [257];
-AVCRC av_crc07 [257];
+static struct {
+ uint8_t le;
+ uint8_t bits;
+ uint32_t poly;
+} av_crc_table_params[AV_CRC_MAX] = {
+ [AV_CRC_8_ATM] = { 0, 8, 0x07 },
+ [AV_CRC_16_ANSI] = { 0, 16, 0x8005 },
+ [AV_CRC_16_CCITT] = { 0, 16, 0x1021 },
+ [AV_CRC_32_IEEE] = { 0, 32, 0x04C11DB7 },
+ [AV_CRC_32_IEEE_LE] = { 1, 32, 0xEDB88320 },
+};
+static AVCRC av_crc_table[AV_CRC_MAX][257];
#endif
/**
- * 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
- * @param le if 1, lowest bit represents coefficient for highest exponent
- * of corresponding polynomial (both for poly and actual CRC).
- * If 0, you must swap the crc parameter and the result of av_crc
+ * Initialize a CRC table.
+ * @param ctx must be an array of size sizeof(AVCRC)*257 or sizeof(AVCRC)*1024
+ * @param le If 1, the lowest bit represents the coefficient for the highest
+ * exponent of the corresponding polynomial (both for poly and
+ * actual CRC).
+ * If 0, you must swap the CRC parameter and the result of av_crc
* if you need the standard representation (can be simplified in
* most cases to e.g. bswap16):
- * bswap_32(crc << (32-bits))
+ * av_bswap32(crc << (32-bits))
* @param bits number of bits for the CRC
* @param poly generator polynomial without the x**bits coefficient, in the
* representation as specified by le
+ * @param ctx_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;
+int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size)
+{
+ unsigned i, j;
uint32_t c;
- if (bits < 8 || bits > 32 || poly >= (1LL<<bits))
+ if (bits < 8 || bits > 32 || poly >= (1LL << bits))
return -1;
- if (ctx_size != sizeof(AVCRC)*257 && ctx_size != sizeof(AVCRC)*1024)
+ 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)));
+ 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);
+ c = (c << 1) ^ ((poly << (32 - bits)) & (((int32_t) c) >> 31));
+ ctx[i] = av_bswap32(c);
}
}
- ctx[256]=1;
-#ifndef CONFIG_SMALL
- if(ctx_size >= sizeof(AVCRC)*1024)
+ ctx[256] = 1;
+#if !CONFIG_SMALL
+ 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 ];
+ for (j = 0; j < 3; j++)
+ ctx[256 *(j + 1) + i] =
+ (ctx[256 * j + i] >> 8) ^ ctx[ctx[256 * j + i] & 0xFF];
#endif
return 0;
}
/**
- * Calculate the CRC of a block
- * @param crc CRC of previous blocks if any or initial value for CRC.
+ * Get an initialized standard CRC table.
+ * @param crc_id ID of a standard CRC
+ * @return a pointer to the CRC table or NULL on failure
+ */
+const AVCRC *av_crc_get_table(AVCRCId crc_id)
+{
+#if !CONFIG_HARDCODED_TABLES
+ if (!av_crc_table[crc_id][FF_ARRAY_ELEMS(av_crc_table[crc_id]) - 1])
+ if (av_crc_init(av_crc_table[crc_id],
+ av_crc_table_params[crc_id].le,
+ av_crc_table_params[crc_id].bits,
+ av_crc_table_params[crc_id].poly,
+ sizeof(av_crc_table[crc_id])) < 0)
+ return NULL;
+#endif
+ return av_crc_table[crc_id];
+}
+
+/**
+ * Calculate the CRC of a block.
+ * @param crc CRC of previous blocks if any or initial value for CRC
* @return CRC updated with the data from the given block
*
* @see av_crc_init() "le" parameter
*/
-uint32_t av_crc(const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length){
- const uint8_t *end= buffer+length;
+uint32_t av_crc(const AVCRC *ctx, uint32_t crc,
+ const uint8_t *buffer, size_t length)
+{
+ const uint8_t *end = buffer + length;
+
+#if !CONFIG_SMALL
+ if (!ctx[256]) {
+ while (((intptr_t) buffer & 3) && buffer < end)
+ crc = ctx[((uint8_t) crc) ^ *buffer++] ^ (crc >> 8);
-#ifndef CONFIG_SMALL
- 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 - 3) {
+ crc ^= av_le2ne32(*(const 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) )];
}
+ }
#endif
- while(buffer<end)
- crc = ctx[((uint8_t)crc) ^ *buffer++] ^ (crc >> 8);
+ while (buffer < end)
+ crc = ctx[((uint8_t) crc) ^ *buffer++] ^ (crc >> 8);
return crc;
}
#ifdef TEST
#undef printf
-main(void){
+int main(void)
+{
uint8_t buf[1999];
int i;
- int p[4][4]={{1, 32, AV_CRC_32_IEEE_LE, 0x3D5CDD04},
- {0, 32, AV_CRC_32_IEEE , 0xC0F5BAE0},
- {0, 16, AV_CRC_16 , 0x1FBB },
- {0, 8, AV_CRC_8_ATM , 0xE3 },};
- AVCRC ctx[1 ? 1024:257];
+ int p[4][3] = { { AV_CRC_32_IEEE_LE, 0xEDB88320, 0x3D5CDD04 },
+ { AV_CRC_32_IEEE , 0x04C11DB7, 0xC0F5BAE0 },
+ { AV_CRC_16_ANSI , 0x8005 , 0x1FBB },
+ { AV_CRC_8_ATM , 0x07 , 0xE3 }
+ };
+ const AVCRC *ctx;
- for(i=0; i<sizeof(buf); i++)
- buf[i]= i+i*i;
+ 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)));
+ for (i = 0; i < 4; i++) {
+ ctx = av_crc_get_table(p[i][0]);
+ printf("crc %08X = %X\n", p[i][1], av_crc(ctx, 0, buf, sizeof(buf)));
}
+ return 0;
}
#endif
projects / ffmpeg / blobdiff