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Mix sound sources in 32-bit buffer, then clip to 16-bit for output. Fixes overflow in some situations, eg MegaRace on SB16.

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This commit is contained in:
SarahW 2016-05-22 16:04:19 +01:00
commit d2b6ea7fa3
15 changed files with 60 additions and 37 deletions
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28
src/sound_sb.c
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@ -11,12 +11,12 @@
typedef struct sb_mixer_t
{
unsigned int master_l, master_r;
unsigned int voice_l, voice_r;
unsigned int fm_l, fm_r;
unsigned int cd_l, cd_r;
unsigned int bass_l, bass_r;
unsigned int treble_l, treble_r;
int master_l, master_r;
int voice_l, voice_r;
int fm_l, fm_r;
int cd_l, cd_r;
int bass_l, bass_r;
int treble_l, treble_r;
int filter;
int index;
@ -41,7 +41,7 @@ static int sb_att[]=
39036,46395,55140,65535
};
static void sb_get_buffer_opl2(int16_t *buffer, int len, void *p)
static void sb_get_buffer_opl2(int32_t *buffer, int len, void *p)
{
sb_t *sb = (sb_t *)p;
sb_mixer_t *mixer = &sb->mixer;
@ -52,7 +52,7 @@ static void sb_get_buffer_opl2(int16_t *buffer, int len, void *p)
sb_dsp_update(&sb->dsp);
for (c = 0; c < len * 2; c += 2)
{
int16_t out_l, out_r;
int32_t out_l, out_r;
out_l = ((sb->opl.buffer[c] * mixer->fm_l) >> 16);
out_r = ((sb->opl.buffer[c + 1] * mixer->fm_r) >> 16);
@ -92,7 +92,7 @@ static void sb_get_buffer_opl2(int16_t *buffer, int len, void *p)
sb->dsp.pos = 0;
}
static void sb_get_buffer_opl3(int16_t *buffer, int len, void *p)
static void sb_get_buffer_opl3(int32_t *buffer, int len, void *p)
{
sb_t *sb = (sb_t *)p;
sb_mixer_t *mixer = &sb->mixer;
@ -104,7 +104,7 @@ static void sb_get_buffer_opl3(int16_t *buffer, int len, void *p)
for (c = 0; c < len * 2; c += 2)
{
int c_emu8k = (((c/2) * 44100) / 48000)*2;
int16_t out_l, out_r;
int32_t out_l, out_r;
out_l = ((sb->opl.buffer[c] * mixer->fm_l) >> 16);
out_r = ((sb->opl.buffer[c + 1] * mixer->fm_r) >> 16);
@ -145,7 +145,7 @@ static void sb_get_buffer_opl3(int16_t *buffer, int len, void *p)
sb->emu8k.pos = 0;
}
static void sb_get_buffer_emu8k(int16_t *buffer, int len, void *p)
static void sb_get_buffer_emu8k(int32_t *buffer, int len, void *p)
{
sb_t *sb = (sb_t *)p;
sb_mixer_t *mixer = &sb->mixer;
@ -158,10 +158,10 @@ static void sb_get_buffer_emu8k(int16_t *buffer, int len, void *p)
for (c = 0; c < len * 2; c += 2)
{
int c_emu8k = (((c/2) * 44100) / 48000)*2;
int16_t out_l, out_r;
int32_t out_l, out_r;
out_l = ((sb->opl.buffer[c] * mixer->fm_l) >> 16);
out_r = ((sb->opl.buffer[c + 1] * mixer->fm_r) >> 16);
out_l = (((int32_t)sb->opl.buffer[c] * (int32_t)mixer->fm_l) >> 16);
out_r = (((int32_t)sb->opl.buffer[c + 1] * (int32_t)mixer->fm_r) >> 16);
out_l += ((sb->emu8k.buffer[c_emu8k] * mixer->fm_l) >> 16);
out_r += ((sb->emu8k.buffer[c_emu8k + 1] * mixer->fm_l) >> 16);