+/*
+ * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * This file is part of Libav.
+ *
+ * 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.
+ *
+ * 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 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"
-AVCRC *av_crcEDB88320;
-AVCRC *av_crc04C11DB7;
-AVCRC *av_crc8005 ;
-AVCRC *av_crc07 ;
+#if CONFIG_HARDCODED_TABLES
+#include "crc_data.h"
+#else
+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
+ * 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):
+ * 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;
+ unsigned i, j;
uint32_t c;
if (bits < 8 || bits > 32 || poly >= (1LL<<bits))
} 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[i] = av_bswap32(c);
}
}
ctx[256]=1;
-#ifndef CONFIG_SMALL
+#if !CONFIG_SMALL
if(ctx_size >= sizeof(AVCRC)*1024)
for (i = 0; i < 256; i++)
for(j=0; j<3; j++)
return 0;
}
+/**
+ * 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;
-#ifndef CONFIG_SMALL
- if(!ctx[256])
+#if !CONFIG_SMALL
+ if(!ctx[256]) {
+ while(((intptr_t) buffer & 3) && buffer < end)
+ crc = ctx[((uint8_t)crc) ^ *buffer++] ^ (crc >> 8);
+
while(buffer<end-3){
- crc ^= le2me_32(*(uint32_t*)buffer); buffer+=4;
+ 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);
#ifdef TEST
#undef printf
-main(){
+int main(void){
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];
+ 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<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)));
+ 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