主要程序是这样的： #include "basic_io.h"
#include "SD_Card.h"
#include <math.h>
#include "system.h"
#include "common.h"
#include "decode.h"
#include "sys/alt_flash.h" unsigned int totpos=0;
unsigned char buf[BITSTREAM_BUFSIZE];
unsigned int frameNum=0,x4;
extern Bit_stream_struc bs;
frame_params fr_ps;
struct Granule grle[2][2]; short dataout[4096]; extern unsigned short *mp3_dat;
extern unsigned int buf_byte_idx; int mp3(unsigned short *mp3data)
{
int a;
III_side_info_t III_side_info;
III_scalefac_t III_scalefac;
layer info;
short pcm_sample[2][SSLIMIT][SBLIMIT];
int i,j,k; mp3_dat=mp3data;
fr_ps.header = &info;
open_bit_stream_r();
frameNum=0;
totpos=0;
buf_byte_idx=0;
while(!bs.eobs) {
if (!seek_sync(SYNC_WORD)) { break;
}
decode_info( );
hdr_to_frps();
frameNum++;
if(frameNum>500) break;
if (info.error_protection)
buffer_CRC();
switch (info.lay) {
case 3:
{
int nSlots, main_data_end, flush_main;
int bytes_to_discard, gr, ch; static int frame_start = 0;
III_get_side_info(&III_side_info);
nSlots = main_data_slots(); for (; nSlots > 0; nSlots--) /* read main data. */
hputbuf((unsigned char) getbit(8));
main_data_end = totpos / 8; /*of privious frame*/
if ( flush_main=(totpos % bitsPerSlot) )
{
hgetbits((int)(bitsPerSlot - flush_main));
main_data_end ++;
}
bytes_to_discard = frame_start - main_data_end - III_side_info.main_data_begin ;
if( main_data_end > BITSTREAM_BUFSIZE )
{
frame_start -= BITSTREAM_BUFSIZE;
rewindNbytes( BITSTREAM_BUFSIZE); // totpos-=4096*8
} frame_start += main_data_slots();
if (bytes_to_discard < 0) { break;
}
for (; bytes_to_discard > 0; bytes_to_discard--)
hgetbits(8); for (gr=0;gr<2;gr++)
{
/* Hybrid filter input */
SS hybridIn[2]; for (ch=0; ch<fr_ps.stereo; ch++)
{
int is[SBLIMIT][SSLIMIT];
int part2_start;
part2_start=totpos;
III_get_scale_factors(&III_scalefac,&III_side_info, gr, ch);
//Huffman III_hufman_decode(&grle[ch][gr],part2_start,is);
III_dequantize_sample(is, hybridIn[ch], &III_scalefac, &grle[ch][gr], ch);
}
III_stereo(hybridIn, &III_scalefac, &grle[0][gr]); for (ch=0; ch<fr_ps.stereo; ch++)
{
III_reorder(hybridIn[ch], &grle[ch][gr]);
III_antialias(hybridIn[ch],&grle[ch][gr]);
Granule_imdct(&grle[ch][gr], ch, hybridIn[ch]);
Granule_freqinverse(hybridIn[ch]);
}
if(fr_ps.stereo == 2)
Granule_subband_synthesis2(hybridIn[0],hybridIn[1],pcm_sample);
else
Granule_subband_synthesis( 0,hybridIn[0],pcm_sample);
/* Output PCM sample points for one granule*/
for(i=0;i<2;i++)
for(j=0;j<SSLIMIT;j++)
for(k=0;k<SBLIMIT;k++)
{ dataout[a]=pcm_sample[j][k];
a++;
}
}
}
break;
default:
break;
}
}
return 0;
}
///////////////////////////
int main(void)
{ unsigned short voicedata[512]={0};
int m,j;
alt_flash_fd *fd;
fd = alt_flash_open_dev(CFI_FLASH_0_NAME);
int ret_code;
if (fd)
{printf("open flash device successfully\n");
for(j=0;j<4;j++)
{ret_code=alt_read_flash(fd, j*1024, voicedata, 1024);
if(!ret_code)
{ printf("read flash success!");
mp3(voicedata);
printf("decode is over!");
for(m=0;m<4096;m++ )
{
while(IORD(AUD_FULL_BASE,0));
IOWR(AUDIO_0_BASE,0,dataout[m]);
IOWR(SEG7_DISPLAY_BASE,0,m);
}
}
alt_flash_close_dev(fd);
}
}
else printf("Can't open flash!");
return 0;
} | 
