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[Core/Sound] fixed YM2612 LFO PM implementation (block & keyscale code should not be modified by LFO)

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This commit is contained in:
EkeEke 2017-04-09 18:54:02 +02:00
parent 5a74df31ee
commit 116b001fb2
1 changed files with 40 additions and 42 deletions
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82
core/sound/ym2612.c
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@ -24,6 +24,9 @@
/*
** CHANGELOG:
**
** 09-04-2017 Eke-Eke (Genesis Plus GX):
** - fixed LFO PM implementation: block & keyscale code should not be modified by LFO (verified on YM2612 die)
**
** 12-03-2017 Eke-Eke (Genesis Plus GX):
** - fixed Op1 self-feedback regression introduced by previous modifications
** - removed one-sample extra delay on Op1 calculated output
@ -1275,31 +1278,25 @@ INLINE void update_ssg_eg_channels(FM_CH *CH)
} while (--i);
}
INLINE void update_phase_lfo_slot(FM_SLOT *SLOT, INT32 pms, UINT32 block_fnum)
INLINE void update_phase_lfo_slot(FM_SLOT *SLOT, UINT32 pm, UINT8 kc, UINT32 fc)
{
INT32 lfo_fn_table_index_offset = lfo_pm_table[(((block_fnum & 0x7f0) >> 4) << 8) + pms + ym2612.OPN.LFO_PM];
INT32 lfo_fn_offset = lfo_pm_table[(((fc & 0x7f0) >> 4) << 8) + pm];
if (lfo_fn_table_index_offset) /* LFO phase modulation active */
if (lfo_fn_offset) /* LFO phase modulation active */
{
UINT8 blk;
unsigned int kc, fc;
/* block is not modified by LFO PM */
UINT8 blk = fc >> 11;
/* there are 2048 FNUMs that can be generated using FNUM/BLK registers
but LFO works with one more bit of a precision so we really need 4096 elements */
block_fnum = block_fnum*2 + lfo_fn_table_index_offset;
blk = (block_fnum&0x7000) >> 12;
block_fnum = block_fnum & 0xfff;
/* LFO works with one more bit of a precision (12-bit) */
fc = ((fc << 1) + lfo_fn_offset) & 0xfff;
/* keyscale code */
kc = (blk<<2) | opn_fktable[block_fnum >> 8];
/* (frequency) phase increment counter */
fc = (((block_fnum << 5) >> (7 - blk)) + SLOT->DT[kc]) & DT_MASK;
/* (frequency) phase increment counter (17-bit) */
fc = (((fc << 5) >> (7 - blk)) + SLOT->DT[kc]) & DT_MASK;
/* update phase */
SLOT->phase += (fc * SLOT->mul) >> 1;
SLOT->phase += ((fc * SLOT->mul) >> 1);
}
else /* LFO phase modulation = zero */
else /* LFO phase modulation = zero */
{
SLOT->phase += SLOT->Incr;
}
@ -1307,39 +1304,36 @@ INLINE void update_phase_lfo_slot(FM_SLOT *SLOT, INT32 pms, UINT32 block_fnum)
INLINE void update_phase_lfo_channel(FM_CH *CH)
{
UINT32 block_fnum = CH->block_fnum;
UINT32 fc = CH->block_fnum;
INT32 lfo_fn_table_index_offset = lfo_pm_table[(((block_fnum & 0x7f0) >> 4) << 8) + CH->pms + ym2612.OPN.LFO_PM];
INT32 lfo_fn_offset = lfo_pm_table[(((fc & 0x7f0) >> 4) << 8) + CH->pms + ym2612.OPN.LFO_PM];
if (lfo_fn_table_index_offset) /* LFO phase modulation active */
if (lfo_fn_offset) /* LFO phase modulation active */
{
UINT8 blk;
unsigned int kc, fc, finc;
/* there are 2048 FNUMs that can be generated using FNUM/BLK registers
but LFO works with one more bit of a precision so we really need 4096 elements */
block_fnum = block_fnum*2 + lfo_fn_table_index_offset;
blk = (block_fnum&0x7000) >> 12;
block_fnum = block_fnum & 0xfff;
/* keyscale code */
kc = (blk<<2) | opn_fktable[block_fnum >> 8];
UINT32 finc;
/* (frequency) phase increment counter */
fc = (block_fnum << 5) >> (7 - blk);
/* block & keyscale code are not modified by LFO PM */
UINT8 blk = fc >> 11;
UINT8 kc = CH->kcode;
/* LFO works with one more bit of a precision (12-bit) */
fc = ((fc << 1) + lfo_fn_offset) & 0xfff;
/* (frequency) phase increment counter (17-bit) */
fc = (fc << 5) >> (7 - blk);
/* apply DETUNE & MUL operator specific values */
finc = (fc + CH->SLOT[SLOT1].DT[kc]) & DT_MASK;
CH->SLOT[SLOT1].phase += (finc*CH->SLOT[SLOT1].mul) >> 1;
CH->SLOT[SLOT1].phase += ((finc * CH->SLOT[SLOT1].mul) >> 1);
finc = (fc + CH->SLOT[SLOT2].DT[kc]) & DT_MASK;
CH->SLOT[SLOT2].phase += (finc*CH->SLOT[SLOT2].mul) >> 1;
CH->SLOT[SLOT2].phase += ((finc * CH->SLOT[SLOT2].mul) >> 1);
finc = (fc + CH->SLOT[SLOT3].DT[kc]) & DT_MASK;
CH->SLOT[SLOT3].phase += (finc*CH->SLOT[SLOT3].mul) >> 1;
CH->SLOT[SLOT3].phase += ((finc * CH->SLOT[SLOT3].mul) >> 1);
finc = (fc + CH->SLOT[SLOT4].DT[kc]) & DT_MASK;
CH->SLOT[SLOT4].phase += (finc*CH->SLOT[SLOT4].mul) >> 1;
CH->SLOT[SLOT4].phase += ((finc * CH->SLOT[SLOT4].mul) >> 1);
}
else /* LFO phase modulation = zero */
{
@ -1477,13 +1471,17 @@ INLINE void chan_calc(FM_CH *CH, int num)
/* update phase counters AFTER output calculations */
if(CH->pms)
{
/* add support for 3 slot mode */
/* 3-slot mode */
if ((ym2612.OPN.ST.mode & 0xC0) && (CH == &ym2612.CH[2]))
{
update_phase_lfo_slot(&CH->SLOT[SLOT1], CH->pms, ym2612.OPN.SL3.block_fnum[1]);
update_phase_lfo_slot(&CH->SLOT[SLOT2], CH->pms, ym2612.OPN.SL3.block_fnum[2]);
update_phase_lfo_slot(&CH->SLOT[SLOT3], CH->pms, ym2612.OPN.SL3.block_fnum[0]);
update_phase_lfo_slot(&CH->SLOT[SLOT4], CH->pms, CH->block_fnum);
/* keyscale code is not modifiedby LFO */
UINT8 kc = CH->kcode;
UINT32 pm = CH->pms + ym2612.OPN.LFO_PM;
update_phase_lfo_slot(&CH->SLOT[SLOT1], pm, kc, ym2612.OPN.SL3.block_fnum[1]);
update_phase_lfo_slot(&CH->SLOT[SLOT2], pm, kc, ym2612.OPN.SL3.block_fnum[2]);
update_phase_lfo_slot(&CH->SLOT[SLOT3], pm, kc, ym2612.OPN.SL3.block_fnum[0]);
update_phase_lfo_slot(&CH->SLOT[SLOT4], pm, kc, CH->block_fnum);
}
else
{