ref: 4f4a0b78514eabbd3d5c1e86a178bd3628d37435
dir: /snd_mix.c/
// snd_mix.c -- portable code to mix sounds for snd_dma.c #include <u.h> #include <libc.h> #include <stdio.h> #include "quakedef.h" #define DWORD u32int #define PAINTBUFFER_SIZE 512 portable_samplepair_t paintbuffer[PAINTBUFFER_SIZE]; int snd_scaletable[32][256]; int *snd_p, snd_linear_count, snd_vol; short *snd_out; void Snd_WriteLinearBlastStereo16 (void) { int i; int val; for (i=0 ; i<snd_linear_count ; i+=2) { val = (snd_p[i]*snd_vol)>>8; if (val > 0x7fff) snd_out[i] = 0x7fff; else if (val < (short)0x8000) snd_out[i] = (short)0x8000; else snd_out[i] = val; val = (snd_p[i+1]*snd_vol)>>8; if (val > 0x7fff) snd_out[i+1] = 0x7fff; else if (val < (short)0x8000) snd_out[i+1] = (short)0x8000; else snd_out[i+1] = val; } } void S_TransferStereo16 (int endtime) { int lpos; int lpaintedtime; DWORD *pbuf; snd_vol = volume.value*256; snd_p = (int *) paintbuffer; lpaintedtime = paintedtime; pbuf = (DWORD *)shm->buffer; while (lpaintedtime < endtime) { // handle recirculating buffer issues lpos = lpaintedtime & ((shm->samples>>1)-1); snd_out = (short *) pbuf + (lpos<<1); snd_linear_count = (shm->samples>>1) - lpos; if (lpaintedtime + snd_linear_count > endtime) snd_linear_count = endtime - lpaintedtime; snd_linear_count <<= 1; // write a linear blast of samples Snd_WriteLinearBlastStereo16 (); snd_p += snd_linear_count; lpaintedtime += (snd_linear_count>>1); } } void S_TransferPaintBuffer(int endtime) { int out_idx; int count; int out_mask; int *p; int step; int val; int snd_vol; DWORD *pbuf; if (shm->samplebits == 16 && shm->channels == 2) { S_TransferStereo16 (endtime); return; } p = (int *) paintbuffer; count = (endtime - paintedtime) * shm->channels; out_mask = shm->samples - 1; out_idx = paintedtime * shm->channels & out_mask; step = 3 - shm->channels; snd_vol = volume.value*256; pbuf = (DWORD *)shm->buffer; if (shm->samplebits == 16) { short *out = (short *) pbuf; while (count--) { val = (*p * snd_vol) >> 8; p+= step; if (val > 0x7fff) val = 0x7fff; else if (val < (short)0x8000) val = (short)0x8000; out[out_idx] = val; out_idx = (out_idx + 1) & out_mask; } } else if (shm->samplebits == 8) { unsigned char *out = (unsigned char *) pbuf; while (count--) { val = (*p * snd_vol) >> 8; p+= step; if (val > 0x7fff) val = 0x7fff; else if (val < (short)0x8000) val = (short)0x8000; out[out_idx] = (val>>8) + 128; out_idx = (out_idx + 1) & out_mask; } } } /* =============================================================================== CHANNEL MIXING =============================================================================== */ void SND_PaintChannelFrom8 (channel_t *ch, sfxcache_t *sc, int endtime); void SND_PaintChannelFrom16 (channel_t *ch, sfxcache_t *sc, int endtime); void S_PaintChannels(int endtime) { int i; int end; channel_t *ch; sfxcache_t *sc; int ltime, count; while (paintedtime < endtime) { // if paintbuffer is smaller than DMA buffer end = endtime; if (endtime - paintedtime > PAINTBUFFER_SIZE) end = paintedtime + PAINTBUFFER_SIZE; // clear the paint buffer memset(paintbuffer, 0, (end - paintedtime) * sizeof *paintbuffer); // paint in the channels. ch = channels; for (i=0; i<total_channels ; i++, ch++) { if (!ch->sfx) continue; if (!ch->leftvol && !ch->rightvol) continue; sc = S_LoadSound (ch->sfx); if (!sc) continue; ltime = paintedtime; while (ltime < end) { // paint up to end if (ch->end < end) count = ch->end - ltime; else count = end - ltime; if (count > 0) { if (sc->width == 1) SND_PaintChannelFrom8(ch, sc, count); else SND_PaintChannelFrom16(ch, sc, count); ltime += count; } // if at end of loop, restart if (ltime >= ch->end) { if (sc->loopstart >= 0) { ch->pos = sc->loopstart; ch->end = ltime + sc->length - ch->pos; } else { // channel just stopped ch->sfx = nil; break; } } } } // transfer out according to DMA format S_TransferPaintBuffer(end); paintedtime = end; } } void SND_InitScaletable (void) { int i, j; for (i=0 ; i<32 ; i++) for (j=0 ; j<256 ; j++) snd_scaletable[i][j] = ((signed char)j) * i * 8; } void SND_PaintChannelFrom8 (channel_t *ch, sfxcache_t *sc, int count) { int data; int *lscale, *rscale; uchar *sfx; int i; if (ch->leftvol > 255) ch->leftvol = 255; if (ch->rightvol > 255) ch->rightvol = 255; lscale = snd_scaletable[ch->leftvol >> 3]; rscale = snd_scaletable[ch->rightvol >> 3]; sfx = (uchar *)((uintptr)sc->data + (uintptr)ch->pos); for (i=0 ; i<count ; i++) { data = sfx[i]; paintbuffer[i].left += lscale[data]; paintbuffer[i].right += rscale[data]; } ch->pos += count; } void SND_PaintChannelFrom16 (channel_t *ch, sfxcache_t *sc, int count) { int data; int left, right; int leftvol, rightvol; signed short *sfx; int i; leftvol = ch->leftvol; rightvol = ch->rightvol; sfx = (signed short *)sc->data + ch->pos; for (i=0 ; i<count ; i++) { data = sfx[i]; left = (data * leftvol) >> 8; right = (data * rightvol) >> 8; paintbuffer[i].left += left; paintbuffer[i].right += right; } ch->pos += count; }