hvirtual/libmpeg3/bitstream.c

   1 #include "mpeg3private.h"
   2 #include "mpeg3protos.h"
   3
   4 #include <stdlib.h>
   5
   6 mpeg3_bits_t* mpeg3bits_new_stream(mpeg3_t *file, mpeg3_demuxer_t *demuxer)
   7 {
   8         mpeg3_bits_t *stream = malloc(sizeof(mpeg3_bits_t));
   9         stream->bfr = 0;
  10         stream->bfr_size = 0;
  11         stream->bit_number = 0;
  12         stream->file = file;
  13         stream->demuxer = demuxer;
  14         stream->input_ptr = 0;
  15         return stream;
  16 }
  17
  18 int mpeg3bits_delete_stream(mpeg3_bits_t* stream)
  19 {
  20         free(stream);
  21         return 0;
  22 }
  23
  24
  25 /* Fill a buffer.  Only works if bit_number is on an 8 bit boundary */
  26 int mpeg3bits_read_buffer(mpeg3_bits_t* stream, unsigned char *buffer, int bytes)
  27 {
  28         int result, i = 0;
  29         while(stream->bit_number > 0)
  30         {
  31                 stream->bit_number -= 8;
  32                 mpeg3demux_read_prev_char(stream->demuxer);
  33         }
  34
  35         stream->bit_number = 0;
  36         stream->bfr_size = 0;
  37         stream->bfr = 0;
  38         result = mpeg3demux_read_data(stream->demuxer, buffer, bytes);
  39         return result;
  40 }
  41
  42 /* For mp3 decompression use a pointer in a buffer for getbits. */
  43 int mpeg3bits_use_ptr(mpeg3_bits_t* stream, unsigned char *buffer)
  44 {
  45         stream->bfr_size = stream->bit_number = 0;
  46         stream->bfr = 0;
  47         stream->input_ptr = buffer;
  48         return 0;
  49 }
  50
  51 /* Go back to using the demuxer for getbits in mp3. */
  52 int mpeg3bits_use_demuxer(mpeg3_bits_t* stream)
  53 {
  54         if(stream->input_ptr)
  55         {
  56                 stream->bfr_size = stream->bit_number = 0;
  57                 stream->input_ptr = 0;
  58                 stream->bfr = 0;
  59         }
  60
  61         return 0;
  62 }
  63
  64 /* Reconfigure for reverse operation */
  65 /* Default is forward operation */
  66 void mpeg3bits_start_reverse(mpeg3_bits_t* stream)
  67 {
  68         int i;
  69         for(i = 0; i < stream->bfr_size; i += 8)
  70                 if(stream->input_ptr)
  71                         stream->input_ptr--;
  72                 else
  73                         mpeg3demux_read_prev_char(stream->demuxer);
  74 }
  75
  76 /* Reconfigure for forward operation */
  77 void mpeg3bits_start_forward(mpeg3_bits_t* stream)
  78 {
  79         int i;
  80         for(i = 0; i < stream->bfr_size; i += 8)
  81                 if(stream->input_ptr)
  82                         stream->input_ptr++;
  83                 else
  84                         mpeg3demux_read_char(stream->demuxer);
  85 }
  86
  87 /* Erase the buffer with the next 4 bytes in the file. */
  88 int mpeg3bits_refill(mpeg3_bits_t* stream)
  89 {
  90         stream->bit_number = 32;
  91         stream->bfr_size = 32;
  92
  93         if(stream->input_ptr)
  94         {
  95                 stream->bfr = (unsigned int)(*stream->input_ptr++) << 24;
  96                 stream->bfr |= (unsigned int)(*stream->input_ptr++) << 16;
  97                 stream->bfr |= (unsigned int)(*stream->input_ptr++) << 8;
  98                 stream->bfr |= *stream->input_ptr++;
  99         }
 100         else
 101         {
 102                 stream->bfr = mpeg3demux_read_char(stream->demuxer) << 24;
 103                 stream->bfr |= mpeg3demux_read_char(stream->demuxer) << 16;
 104                 stream->bfr |= mpeg3demux_read_char(stream->demuxer) << 8;
 105                 stream->bfr |= mpeg3demux_read_char(stream->demuxer);
 106         }
 107         return mpeg3demux_eof(stream->demuxer);
 108 }
 109
 110 /* Erase the buffer with the previous 4 bytes in the file. */
 111 int mpeg3bits_refill_backwards(mpeg3_bits_t* stream)
 112 {
 113         stream->bit_number = 0;
 114         stream->bfr_size = 32;
 115         stream->bfr = mpeg3demux_read_prev_char(stream->demuxer);
 116         stream->bfr |= (unsigned int)mpeg3demux_read_prev_char(stream->demuxer) << 8;
 117         stream->bfr |= (unsigned int)mpeg3demux_read_prev_char(stream->demuxer) << 16;
 118         stream->bfr |= (unsigned int)mpeg3demux_read_prev_char(stream->demuxer) << 24;
 119         return mpeg3demux_eof(stream->demuxer);
 120 }
 121
 122 int mpeg3bits_byte_align(mpeg3_bits_t *stream)
 123 {
 124         stream->bit_number = (stream->bit_number + 7) & 0xf8;
 125         return 0;
 126 }
 127
 128 int mpeg3bits_seek_end(mpeg3_bits_t* stream)
 129 {
 130         stream->bfr_size = stream->bit_number = 0;
 131         return mpeg3demux_seek_end(stream->demuxer);
 132 }
 133
 134 int mpeg3bits_open_title(mpeg3_bits_t* stream, int title)
 135 {
 136         stream->bfr_size = stream->bit_number = 0;
 137         return mpeg3demux_open_title(stream->demuxer, title);
 138 }
 139
 140 int mpeg3bits_seek_start(mpeg3_bits_t* stream)
 141 {
 142         stream->bfr_size = stream->bit_number = 0;
 143         return mpeg3demux_seek_start(stream->demuxer);
 144 }
 145
 146 int mpeg3bits_seek_time(mpeg3_bits_t* stream, double time_position)
 147 {
 148         stream->bfr_size = stream->bit_number = 0;
 149         return mpeg3demux_seek_time(stream->demuxer, time_position);
 150 }
 151
 152 int mpeg3bits_seek_byte(mpeg3_bits_t* stream, int64_t position)
 153 {
 154         stream->bfr_size = stream->bit_number = 0;
 155         return mpeg3demux_seek_byte(stream->demuxer, position);
 156 }
 157
 158 int mpeg3bits_seek_percentage(mpeg3_bits_t* stream, double percentage)
 159 {
 160         stream->bfr_size = stream->bit_number = 0;
 161         return mpeg3demux_seek_percentage(stream->demuxer, percentage);
 162 }
 163
 164 int64_t mpeg3bits_tell(mpeg3_bits_t* stream)
 165 {
 166         return mpeg3demux_tell(stream->demuxer);
 167 }
 168
 169 int mpeg3bits_getbitoffset(mpeg3_bits_t *stream)
 170 {
 171         return stream->bit_number & 7;
 172 }
 173