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/*
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 * Common bit i/o utils
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 * Copyright (c) 2000, 2001 Fabrice Bellard.
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 *
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 * This library is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2 of the License, or (at your option) any later version.
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 *
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 * This library is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with this library; if not, write to the Free Software
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 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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 *
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 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
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 */
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/**
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 * @file common.c
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 * common internal api.
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 */
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#include "avcodec.h"
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const uint8_t ff_sqrt_tab[128]={
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        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,
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        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,
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        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,
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        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
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};
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const uint8_t ff_log2_tab[256]={
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        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,
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        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,
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        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,
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        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,
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        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,
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        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,
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        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,
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        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
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};
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void init_put_bits(PutBitContext *s, 
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                   uint8_t *buffer, int buffer_size,
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                   void *opaque,
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                   void (*write_data)(void *, uint8_t *, int))
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{
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    s->buf = buffer;
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    s->buf_end = s->buf + buffer_size;
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    s->data_out_size = 0;
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    if(write_data!=NULL) 
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    {
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            fprintf(stderr, "write Data callback is not supported\n");
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    }
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#ifdef ALT_BITSTREAM_WRITER
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    s->index=0;
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    ((uint32_t*)(s->buf))[0]=0;
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//    memset(buffer, 0, buffer_size);
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#else
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    s->buf_ptr = s->buf;
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    s->bit_left=32;
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    s->bit_buf=0;
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#endif
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}
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/* return the number of bits output */
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int64_t get_bit_count(PutBitContext *s)
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{
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#ifdef ALT_BITSTREAM_WRITER
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    return s->data_out_size * 8 + s->index;
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#else
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    return (s->buf_ptr - s->buf + s->data_out_size) * 8 + 32 - (int64_t)s->bit_left;
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#endif
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}
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void align_put_bits(PutBitContext *s)
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{
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#ifdef ALT_BITSTREAM_WRITER
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    put_bits(s,(  - s->index) & 7,0);
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#else
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    put_bits(s,s->bit_left & 7,0);
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#endif
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}
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/* pad the end of the output stream with zeros */
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void flush_put_bits(PutBitContext *s)
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{
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#ifdef ALT_BITSTREAM_WRITER
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    align_put_bits(s);
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#else
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    s->bit_buf<<= s->bit_left;
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    while (s->bit_left < 32) {
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        /* XXX: should test end of buffer */
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        *s->buf_ptr++=s->bit_buf >> 24;
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        s->bit_buf<<=8;
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        s->bit_left+=8;
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    }
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    s->bit_left=32;
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    s->bit_buf=0;
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#endif
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}
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void put_string(PutBitContext * pbc, char *s)
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{
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    while(*s){
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        put_bits(pbc, 8, *s);
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        s++;
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    }
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    put_bits(pbc, 8, 0);
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}
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/* bit input functions */
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void init_get_bits(GetBitContext *s,
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                   const uint8_t *buffer, int bit_size)
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{
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    const int buffer_size= (bit_size+7)>>3;
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    s->buffer= buffer;
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    s->size_in_bits= bit_size;
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    s->buffer_end= buffer + buffer_size;
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#ifdef ALT_BITSTREAM_READER
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    s->index=0;
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#elif defined LIBMPEG2_BITSTREAM_READER
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    s->buffer_ptr = buffer;
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    s->bit_count = 16;
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    s->cache = 0;
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#elif defined A32_BITSTREAM_READER
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    s->buffer_ptr = (uint32_t*)buffer;
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    s->bit_count = 32;
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    s->cache0 = 0;
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    s->cache1 = 0;
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#endif
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    {
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        OPEN_READER(re, s)
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        UPDATE_CACHE(re, s)
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//        UPDATE_CACHE(re, s)
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        CLOSE_READER(re, s)
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    }
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#ifdef A32_BITSTREAM_READER
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    s->cache1 = 0;
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#endif
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}
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void align_get_bits(GetBitContext *s)
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{
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    int n= (-get_bits_count(s)) & 7;
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    if(n) skip_bits(s, n);
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}
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int check_marker(GetBitContext *s, const char *msg)
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{
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    int bit= get_bits1(s);
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    if(!bit) printf("Marker bit missing %s\n", msg);
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    return bit;
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}
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/* VLC decoding */
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//#define DEBUG_VLC
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#define GET_DATA(v, table, i, wrap, size) \
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{\
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    const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
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    switch(size) {\
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    case 1:\
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        v = *(const uint8_t *)ptr;\
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        break;\
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    case 2:\
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        v = *(const uint16_t *)ptr;\
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        break;\
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    default:\
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        v = *(const uint32_t *)ptr;\
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        break;\
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    }\
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}
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static int alloc_table(VLC *vlc, int size)
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{
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    int index;
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    index = vlc->table_size;
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    vlc->table_size += size;
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    if (vlc->table_size > vlc->table_allocated) {
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        vlc->table_allocated += (1 << vlc->bits);
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        vlc->table = av_realloc(vlc->table,
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                                sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
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        if (!vlc->table)
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            return -1;
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    }
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    return index;
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}
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static int build_table(VLC *vlc, int table_nb_bits,
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                       int nb_codes,
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                       const void *bits, int bits_wrap, int bits_size,
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                       const void *codes, int codes_wrap, int codes_size,
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                       uint32_t code_prefix, int n_prefix)
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{
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    int i, j, k, n, table_size, table_index, nb, n1, index;
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    uint32_t code;
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    VLC_TYPE (*table)[2];
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    table_size = 1 << table_nb_bits;
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    table_index = alloc_table(vlc, table_size);
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#ifdef DEBUG_VLC
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    printf("new table index=%d size=%d code_prefix=%x n=%d\n",
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           table_index, table_size, code_prefix, n_prefix);
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#endif
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    if (table_index < 0)
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        return -1;
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    table = &vlc->table[table_index];
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    for(i=0;i<table_size;i++) {
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        table[i][1] = 0; //bits
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        table[i][0] = -1; //codes
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    }
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    /* first pass: map codes and compute auxillary table sizes */
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    for(i=0;i<nb_codes;i++) {
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        GET_DATA(n, bits, i, bits_wrap, bits_size);
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        GET_DATA(code, codes, i, codes_wrap, codes_size);
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        /* we accept tables with holes */
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        if (n <= 0)
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            continue;
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#if defined(DEBUG_VLC) && 0
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        printf("i=%d n=%d code=0x%x\n", i, n, code);
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#endif
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        /* if code matches the prefix, it is in the table */
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        n -= n_prefix;
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        if (n > 0 && (code >> n) == code_prefix) {
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            if (n <= table_nb_bits) {
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                /* no need to add another table */
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                j = (code << (table_nb_bits - n)) & (table_size - 1);
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                nb = 1 << (table_nb_bits - n);
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                for(k=0;k<nb;k++) {
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#ifdef DEBUG_VLC
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                    printf("%4x: code=%d n=%d\n",
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                           j, i, n);
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#endif
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                    if (table[j][1] /*bits*/ != 0) {
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                        fprintf(stderr, "incorrect codes\n");
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                        exit(1);
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                    }
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                    table[j][1] = n; //bits
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                    table[j][0] = i; //code
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                    j++;
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                }
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            } else {
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                n -= table_nb_bits;
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                j = (code >> n) & ((1 << table_nb_bits) - 1);
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#ifdef DEBUG_VLC
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                printf("%4x: n=%d (subtable)\n",
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                       j, n);
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#endif
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                /* compute table size */
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                n1 = -table[j][1]; //bits
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                if (n > n1)
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                    n1 = n;
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                table[j][1] = -n1; //bits
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            }
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        }
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    }
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    /* second pass : fill auxillary tables recursively */
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    for(i=0;i<table_size;i++) {
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        n = table[i][1]; //bits
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        if (n < 0) {
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            n = -n;
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            if (n > table_nb_bits) {
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                n = table_nb_bits;
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                table[i][1] = -n; //bits
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            }
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            index = build_table(vlc, n, nb_codes,
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                                bits, bits_wrap, bits_size,
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                                codes, codes_wrap, codes_size,
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                                (code_prefix << table_nb_bits) | i,
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                                n_prefix + table_nb_bits);
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            if (index < 0)
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                return -1;
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            /* note: realloc has been done, so reload tables */
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            table = &vlc->table[table_index];
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            table[i][0] = index; //code
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        }
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    }
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    return table_index;
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}
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/* Build VLC decoding tables suitable for use with get_vlc().
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   'nb_bits' set thee decoding table size (2^nb_bits) entries. The
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   bigger it is, the faster is the decoding. But it should not be too
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   big to save memory and L1 cache. '9' is a good compromise.
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   'nb_codes' : number of vlcs codes
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   'bits' : table which gives the size (in bits) of each vlc code.
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   'codes' : table which gives the bit pattern of of each vlc code.
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   'xxx_wrap' : give the number of bytes between each entry of the
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   'bits' or 'codes' tables.
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   'xxx_size' : gives the number of bytes of each entry of the 'bits'
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   or 'codes' tables.
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   'wrap' and 'size' allows to use any memory configuration and types
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   (byte/word/long) to store the 'bits' and 'codes' tables.  
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*/
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int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
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             const void *bits, int bits_wrap, int bits_size,
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             const void *codes, int codes_wrap, int codes_size)
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{
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    vlc->bits = nb_bits;
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    vlc->table = NULL;
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    vlc->table_allocated = 0;
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    vlc->table_size = 0;
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#ifdef DEBUG_VLC
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    printf("build table nb_codes=%d\n", nb_codes);
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#endif
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    if (build_table(vlc, nb_bits, nb_codes,
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                    bits, bits_wrap, bits_size,
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                    codes, codes_wrap, codes_size,
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                    0, 0) < 0) {
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        av_free(vlc->table);
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        return -1;
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    }
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    return 0;
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}
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void free_vlc(VLC *vlc)
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{
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    av_free(vlc->table);
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}
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int ff_gcd(int a, int b){
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    if(b) return ff_gcd(b, a%b);
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    else  return a;
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}
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void ff_float2fraction(int *nom_arg, int *denom_arg, double f, int max){
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    double best_diff=1E10, diff;
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    int best_denom=1, best_nom=1;
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    int nom, denom, gcd;
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    //brute force here, perhaps we should try continued fractions if we need large max ...
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    for(denom=1; denom<=max; denom++){
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        nom= (int)(f*denom + 0.5);
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        if(nom<=0 || nom>max) continue;
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        diff= ABS( f - (double)nom / (double)denom );
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        if(diff < best_diff){
361
            best_diff= diff;
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            best_nom= nom;
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            best_denom= denom;
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        }
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    }
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367
    gcd= ff_gcd(best_nom, best_denom);
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    best_nom   /= gcd;
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    best_denom /= gcd;
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    *nom_arg= best_nom;
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    *denom_arg= best_denom;
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}