/* * Common bit i/o utils * Copyright (c) 2000, 2001 Fabrice Bellard. * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> * * This library 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 of the License, or (at your option) any later version. * * 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. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at> */ /** * @file common.c * common internal api. */ #include "avcodec.h" const uint8_t ff_sqrt_tab[128]={ 0, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11 }; const uint8_t ff_log2_tab[256]={ 0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4, 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5, 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6, 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6, 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7 }; void align_put_bits(PutBitContext *s) { #ifdef ALT_BITSTREAM_WRITER put_bits(s,( - s->index) & 7,0); #else put_bits(s,s->bit_left & 7,0); #endif } void put_string(PutBitContext * pbc, char *s, int put_zero) { while(*s){ put_bits(pbc, 8, *s); s++; } if(put_zero) put_bits(pbc, 8, 0); } /* bit input functions */ /** * reads 0-32 bits. */ unsigned int get_bits_long(GetBitContext *s, int n){ if(n<=17) return get_bits(s, n); else{ int ret= get_bits(s, 16) << (n-16); return ret | get_bits(s, n-16); } } /** * shows 0-32 bits. */ unsigned int show_bits_long(GetBitContext *s, int n){ if(n<=17) return show_bits(s, n); else{ GetBitContext gb= *s; int ret= get_bits_long(s, n); *s= gb; return ret; } } void align_get_bits(GetBitContext *s) { int n= (-get_bits_count(s)) & 7; if(n) skip_bits(s, n); } int check_marker(GetBitContext *s, const char *msg) { int bit= get_bits1(s); if(!bit) av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg); return bit; } /* VLC decoding */ //#define DEBUG_VLC #define GET_DATA(v, table, i, wrap, size) \ {\ const uint8_t *ptr = (const uint8_t *)table + i * wrap;\ switch(size) {\ case 1:\ v = *(const uint8_t *)ptr;\ break;\ case 2:\ v = *(const uint16_t *)ptr;\ break;\ default:\ v = *(const uint32_t *)ptr;\ break;\ }\ } static int alloc_table(VLC *vlc, int size) { int index; index = vlc->table_size; vlc->table_size += size; if (vlc->table_size > vlc->table_allocated) { vlc->table_allocated += (1 << vlc->bits); vlc->table = av_realloc(vlc->table, sizeof(VLC_TYPE) * 2 * vlc->table_allocated); if (!vlc->table) return -1; } return index; } static int build_table(VLC *vlc, int table_nb_bits, int nb_codes, const void *bits, int bits_wrap, int bits_size, const void *codes, int codes_wrap, int codes_size, uint32_t code_prefix, int n_prefix) { int i, j, k, n, table_size, table_index, nb, n1, index; uint32_t code; VLC_TYPE (*table)[2]; table_size = 1 << table_nb_bits; table_index = alloc_table(vlc, table_size); #ifdef DEBUG_VLC printf("new table index=%d size=%d code_prefix=%x n=%d\n", table_index, table_size, code_prefix, n_prefix); #endif if (table_index < 0) return -1; table = &vlc->table[table_index]; for(i=0;i<table_size;i++) { table[i][1] = 0; //bits table[i][0] = -1; //codes } /* first pass: map codes and compute auxillary table sizes */ for(i=0;i<nb_codes;i++) { GET_DATA(n, bits, i, bits_wrap, bits_size); GET_DATA(code, codes, i, codes_wrap, codes_size); /* we accept tables with holes */ if (n <= 0) continue; #if defined(DEBUG_VLC) && 0 printf("i=%d n=%d code=0x%x\n", i, n, code); #endif /* if code matches the prefix, it is in the table */ n -= n_prefix; if (n > 0 && (code >> n) == code_prefix) { if (n <= table_nb_bits) { /* no need to add another table */ j = (code << (table_nb_bits - n)) & (table_size - 1); nb = 1 << (table_nb_bits - n); for(k=0;k<nb;k++) { #ifdef DEBUG_VLC av_log(NULL, AV_LOG_DEBUG, "%4x: code=%d n=%d\n", j, i, n); #endif if (table[j][1] /*bits*/ != 0) { av_log(NULL, AV_LOG_ERROR, "incorrect codes\n"); av_abort(); } table[j][1] = n; //bits table[j][0] = i; //code j++; } } else { n -= table_nb_bits; j = (code >> n) & ((1 << table_nb_bits) - 1); #ifdef DEBUG_VLC printf("%4x: n=%d (subtable)\n", j, n); #endif /* compute table size */ n1 = -table[j][1]; //bits if (n > n1) n1 = n; table[j][1] = -n1; //bits } } } /* second pass : fill auxillary tables recursively */ for(i=0;i<table_size;i++) { n = table[i][1]; //bits if (n < 0) { n = -n; if (n > table_nb_bits) { n = table_nb_bits; table[i][1] = -n; //bits } index = build_table(vlc, n, nb_codes, bits, bits_wrap, bits_size, codes, codes_wrap, codes_size, (code_prefix << table_nb_bits) | i, n_prefix + table_nb_bits); if (index < 0) return -1; /* note: realloc has been done, so reload tables */ table = &vlc->table[table_index]; table[i][0] = index; //code } } return table_index; } /* Build VLC decoding tables suitable for use with get_vlc(). 'nb_bits' set thee decoding table size (2^nb_bits) entries. The bigger it is, the faster is the decoding. But it should not be too big to save memory and L1 cache. '9' is a good compromise. 'nb_codes' : number of vlcs codes 'bits' : table which gives the size (in bits) of each vlc code. 'codes' : table which gives the bit pattern of of each vlc code. 'xxx_wrap' : give the number of bytes between each entry of the 'bits' or 'codes' tables. 'xxx_size' : gives the number of bytes of each entry of the 'bits' or 'codes' tables. 'wrap' and 'size' allows to use any memory configuration and types (byte/word/long) to store the 'bits' and 'codes' tables. */ int init_vlc(VLC *vlc, int nb_bits, int nb_codes, const void *bits, int bits_wrap, int bits_size, const void *codes, int codes_wrap, int codes_size) { vlc->bits = nb_bits; vlc->table = NULL; vlc->table_allocated = 0; vlc->table_size = 0; #ifdef DEBUG_VLC printf("build table nb_codes=%d\n", nb_codes); #endif if (build_table(vlc, nb_bits, nb_codes, bits, bits_wrap, bits_size, codes, codes_wrap, codes_size, 0, 0) < 0) { av_free(vlc->table); return -1; } return 0; } void free_vlc(VLC *vlc) { av_free(vlc->table); } int64_t ff_gcd(int64_t a, int64_t b){ if(b) return ff_gcd(b, a%b); else return a; }