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sound, add ym2612 channel clipping, ladder effect

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This commit is contained in:
kub 2021-11-17 22:27:02 +01:00
parent 55615f9c97
commit 8794ba5c8d
7 changed files with 39 additions and 9 deletions
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26
pico/sound/ym2612.c
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@ -918,6 +918,14 @@ typedef struct
#if !defined(_ASM_YM2612_C) || defined(EXTERNAL_YM2612)
#include <limits.h>
static int clip(int n)
{
unsigned b = 14, s = n < 0;
if (s + (n>>(b-1))) n = (int)(s + INT_MAX) >> (8*sizeof(int)-b);
return n;
}
static void chan_render_loop(chan_rend_context *ct, int *buffer, int length)
{
int scounter; /* sample counter */
@ -1226,6 +1234,7 @@ static void chan_render_loop(chan_rend_context *ct, int *buffer, int length)
/* mix sample to output buffer */
if (smp) {
smp = clip(smp); /* saturate to 14 bit */
if (ct->pack & 1) { /* stereo */
if (ct->pack & 0x20) /* L */ /* TODO: check correctness */
buffer[scounter*2] += smp;
@ -1256,12 +1265,21 @@ static void chan_render_prep(void)
crct.lfo_inc = ym2612.OPN.lfo_inc;
}
static void chan_render_finish(void)
static void chan_render_finish(int *buffer, unsigned short length, int active_chans)
{
ym2612.OPN.eg_cnt = crct.eg_cnt;
ym2612.OPN.eg_timer = crct.eg_timer;
g_lfo_ampm = crct.pack >> 16; // need_save
ym2612.OPN.lfo_cnt = crct.lfo_cnt;
/* apply ladder effect. NB only works if buffer was empty beforehand! */
if (active_chans && (ym2612.OPN.ST.flags & ST_LADDER)) {
length <<= crct.pack & 1;
while (length--) {
*buffer -= (*buffer < 0)*4 << 5;
buffer++;
}
}
}
static UINT32 update_lfo_phase(FM_SLOT *SLOT, UINT32 block_fnum)
@ -1835,21 +1853,21 @@ int YM2612UpdateOne_(int *buffer, int length, int stereo, int is_buf_empty)
BIT_IF(flags, 1, (ym2612.ssg_mask & 0xf00000) && (ym2612.OPN.ST.flags & 1));
if (ym2612.slot_mask & 0xf00000) active_chs |= chan_render(buffer, length, 5, flags|((pan&0xc00)>>6)|(!!ym2612.dacen<<2)) << 5;
#undef BIT_IF
chan_render_finish();
chan_render_finish(buffer, length, active_chs);
return active_chs; // 1 if buffer updated
}
/* initialize YM2612 emulator */
void YM2612Init_(int clock, int rate, int ssg)
void YM2612Init_(int clock, int rate, int flags)
{
memset(&ym2612, 0, sizeof(ym2612));
init_tables();
ym2612.OPN.ST.clock = clock;
ym2612.OPN.ST.rate = rate;
ym2612.OPN.ST.flags = (ssg ? 1:0);
ym2612.OPN.ST.flags = flags;
OPNSetPres( 6*24 );