Mercurial > SDL_sound_CoreAudio
view decoders/mpglib/decode_i386.c @ 452:6c95cbd55d16
Updated.
author | Ryan C. Gordon <icculus@icculus.org> |
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date | Sat, 13 Sep 2003 20:30:13 +0000 |
parents | 52b9f37998db |
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/* * Mpeg Layer-1,2,3 audio decoder * ------------------------------ * copyright (c) 1995,1996,1997 by Michael Hipp, All rights reserved. * See also 'README' * * slighlty optimized for machines without autoincrement/decrement. * The performance is highly compiler dependend. Maybe * the decode.c version for 'normal' processor may be faster * even for Intel processors. */ #include <stdlib.h> #include <math.h> #include <string.h> #include "mpg123_sdlsound.h" #include "mpglib_sdlsound.h" /* old WRITE_SAMPLE */ #define WRITE_SAMPLE(samples,sum,clip) \ if( (sum) > 32767.0) { *(samples) = 0x7fff; (clip)++; } \ else if( (sum) < -32768.0) { *(samples) = -0x8000; (clip)++; } \ else { *(samples) = sum; } int synth_1to1_mono(real *bandPtr,unsigned char *samples, int *pnt, struct mpstr *mp) { short samples_tmp[64]; short *tmp1 = samples_tmp; int i,ret; int pnt1 = 0; ret = synth_1to1(bandPtr,0,(unsigned char *) samples_tmp,&pnt1,mp); samples += *pnt; for(i=0;i<32;i++) { *( (short *) samples) = *tmp1; samples += 2; tmp1 += 2; } *pnt += 64; return ret; } int synth_1to1(real *bandPtr,int channel,unsigned char *out, int *pnt, struct mpstr *mp) { static const int step = 2; int bo; short *samples = (short *) (out + *pnt); real *b0,(*buf)[0x110]; int clip = 0; int bo1; bo = mp->synth_bo; if(!channel) { bo--; bo &= 0xf; buf = mp->synth_buffs[0]; } else { samples++; buf = mp->synth_buffs[1]; } if(bo & 0x1) { b0 = buf[0]; bo1 = bo; dct64(buf[1]+((bo+1)&0xf),buf[0]+bo,bandPtr); } else { b0 = buf[1]; bo1 = bo+1; dct64(buf[0]+bo,buf[1]+bo+1,bandPtr); } mp->synth_bo = bo; { register int j; real *window = decwin + 16 - bo1; for (j=16;j;j--,b0+=0x10,window+=0x20,samples+=step) { real sum; sum = window[0x0] * b0[0x0]; sum -= window[0x1] * b0[0x1]; sum += window[0x2] * b0[0x2]; sum -= window[0x3] * b0[0x3]; sum += window[0x4] * b0[0x4]; sum -= window[0x5] * b0[0x5]; sum += window[0x6] * b0[0x6]; sum -= window[0x7] * b0[0x7]; sum += window[0x8] * b0[0x8]; sum -= window[0x9] * b0[0x9]; sum += window[0xA] * b0[0xA]; sum -= window[0xB] * b0[0xB]; sum += window[0xC] * b0[0xC]; sum -= window[0xD] * b0[0xD]; sum += window[0xE] * b0[0xE]; sum -= window[0xF] * b0[0xF]; WRITE_SAMPLE(samples,sum,clip); } { real sum; sum = window[0x0] * b0[0x0]; sum += window[0x2] * b0[0x2]; sum += window[0x4] * b0[0x4]; sum += window[0x6] * b0[0x6]; sum += window[0x8] * b0[0x8]; sum += window[0xA] * b0[0xA]; sum += window[0xC] * b0[0xC]; sum += window[0xE] * b0[0xE]; WRITE_SAMPLE(samples,sum,clip); b0-=0x10,window-=0x20,samples+=step; } window += bo1<<1; for (j=15;j;j--,b0-=0x10,window-=0x20,samples+=step) { real sum; sum = -window[-0x1] * b0[0x0]; sum -= window[-0x2] * b0[0x1]; sum -= window[-0x3] * b0[0x2]; sum -= window[-0x4] * b0[0x3]; sum -= window[-0x5] * b0[0x4]; sum -= window[-0x6] * b0[0x5]; sum -= window[-0x7] * b0[0x6]; sum -= window[-0x8] * b0[0x7]; sum -= window[-0x9] * b0[0x8]; sum -= window[-0xA] * b0[0x9]; sum -= window[-0xB] * b0[0xA]; sum -= window[-0xC] * b0[0xB]; sum -= window[-0xD] * b0[0xC]; sum -= window[-0xE] * b0[0xD]; sum -= window[-0xF] * b0[0xE]; sum -= window[-0x0] * b0[0xF]; WRITE_SAMPLE(samples,sum,clip); } } *pnt += 128; return clip; }