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[Core/Sound] improved MAME YM2413 EG transitions accuracy (verified against https://github.com/nukeykt/Nuked-OPLL/blob/master/opll.c)

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ekeeke 2021-05-09 09:52:44 +02:00
parent 9c3914009c
commit 8acd9def6d
4 changed files with 45 additions and 46 deletions
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91
core/sound/ym2413.c
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@ -37,6 +37,7 @@ to do:
/** 2021/04/25: fixed EG behavior when SL = 0 (verified on YM2413 real hardware, cf. https://www.smspower.org/Development/YM2413ReverseEngineeringNotes2015-12-24) **/
/** 2021/04/25: improved EG sustain phase transition comparator accuracy (verified on YM2413 real hardware, cf. https://www.smspower.org/Development/YM2413ReverseEngineeringNotes2015-12-31) **/
/** 2021/05/04: improved EG increment steps accuracy (verified on YM2413 real hardware, cf. https://www.smspower.org/Development/YM2413ReverseEngineeringNotes2015-03-20) **/
/** 2021/05/08: improved EG transitions accuracy (verified against https://github.com/nukeykt/Nuked-OPLL/blob/master/opll.c) **/
/************************************************/
#include "shared.h"
@ -580,26 +581,15 @@ INLINE void advance(void)
switch(op->state)
{
case EG_DMP: /* dump phase */
if ( !(ym2413.eg_cnt & ((1<<op->eg_sh_dp)-1) ) )
case EG_DMP: /* dump phase */
if ( (op->volume & ~3) == (MAX_ATT_INDEX & ~3) ) /* envelope level lowest 2 bits are ignored by the comparator */
{
op->volume += eg_inc[op->eg_sel_dp + ((ym2413.eg_cnt>>op->eg_sh_dp)&15)];
}
op->state = EG_ATT;
/* attack phase should be started if attenuation is already maximal, without waiting for next envelope update (every 2 samples during dump phase) */
if ( op->volume >= MAX_ATT_INDEX )
{
/* attack phase is skipped and envelope is forced to 0 when attack rate is set to 15.0-15.3 */
/* (verified on real hardware, cf. https://www.smspower.org/Development/YM2413ReverseEngineeringNotes2017-01-26) */
if ((op->ar + op->ksr) < 16+60)
{
op->volume = MAX_ATT_INDEX;
op->state = EG_ATT;
}
else
/* force envelope to zero when attack rate is set to 15.0-15.3 */
if ((op->ar + op->ksr) >= 16+60)
{
op->volume = MIN_ATT_INDEX;
op->state = (op->sl == MIN_ATT_INDEX) ? EG_SUS : EG_DEC; /* decay phase should not occur in case SL = 0 */
}
/*dump phase is performed by both operators in each channel*/
@ -607,32 +597,39 @@ INLINE void advance(void)
*phases in BOTH operators are reset (at the same time ?)
*/
if (i&1)
{
CH->SLOT[0].phase = CH->SLOT[1].phase = 0;
}
}
else if ( !(ym2413.eg_cnt & ((1<<op->eg_sh_dp)-1) ) )
{
op->volume += eg_inc[op->eg_sel_dp + ((ym2413.eg_cnt>>op->eg_sh_dp)&15)];
}
break;
case EG_ATT: /* attack phase */
if ( !(ym2413.eg_cnt & ((1<<op->eg_sh_ar)-1) ) )
case EG_ATT: /* attack phase */
if (op->volume == MIN_ATT_INDEX)
{
op->volume += (~op->volume *
(eg_inc[op->eg_sel_ar + ((ym2413.eg_cnt>>op->eg_sh_ar)&15)])
) >>2;
if (op->volume <= MIN_ATT_INDEX)
{
op->volume = MIN_ATT_INDEX;
op->state = (op->sl == MIN_ATT_INDEX) ? EG_SUS : EG_DEC; /* decay phase should not occur in case SL = 0 */
}
op->state = EG_DEC;
}
else if ( !(ym2413.eg_cnt & ((1<<op->eg_sh_ar)-1) ) )
{
op->volume += (~op->volume * (eg_inc[op->eg_sel_ar + ((ym2413.eg_cnt>>op->eg_sh_ar)&15)])) >>2;
}
break;
case EG_DEC: /* decay phase */
if ( !(ym2413.eg_cnt & ((1<<op->eg_sh_dr)-1) ) )
if ( (op->volume & ~7) == op->sl ) /* envelope level lowest 3 bits are ignored by the comparator */
{
op->state = EG_SUS;
}
else if ( !(ym2413.eg_cnt & ((1<<op->eg_sh_dr)-1) ) )
{
op->volume += eg_inc[op->eg_sel_dr + ((ym2413.eg_cnt>>op->eg_sh_dr)&15)];
if ( (op->volume & ~7) == op->sl ) /* envelope level lowest 3 bits are ignored by the comparator */
op->state = EG_SUS;
if ( (op->volume & ~3) == (MAX_ATT_INDEX & ~3) ) /* envelope level lowest 2 bits are ignored by the comparator */
{
op->state = EG_OFF;
}
}
break;
@ -641,19 +638,20 @@ INLINE void advance(void)
one can change percusive/non-percussive modes on the fly and
the chip will remain in sustain phase - verified on real YM3812 */
if(op->eg_type) /* non-percussive mode (sustained tone) */
if (op->eg_type) /* non-percussive mode (sustained tone) */
{
/* do nothing */
}
else /* percussive mode */
else /* percussive mode */
{
/* during sustain phase chip adds Release Rate (in percussive mode) */
if ( !(ym2413.eg_cnt & ((1<<op->eg_sh_rr)-1) ) )
{
op->volume += eg_inc[op->eg_sel_rr + ((ym2413.eg_cnt>>op->eg_sh_rr)&15)];
if ( op->volume >= MAX_ATT_INDEX )
op->volume = MAX_ATT_INDEX;
if ( (op->volume & ~3) == (MAX_ATT_INDEX & ~3) ) /* envelope level lowest 2 bits are ignored by the comparator */
{
op->state = EG_OFF;
}
}
/* else do nothing in sustain phase */
}
@ -679,7 +677,7 @@ INLINE void advance(void)
*/
if ( (i&1) || ((ym2413.rhythm&0x20) && (i>=12)) )/* exclude modulators */
{
if(op->eg_type) /* non-percussive mode (sustained tone) */
if (op->eg_type) /* non-percussive mode (sustained tone) */
/*this is correct: use RR when SUS = OFF*/
/*and use RS when SUS = ON*/
{
@ -688,9 +686,8 @@ INLINE void advance(void)
if ( !(ym2413.eg_cnt & ((1<<op->eg_sh_rs)-1) ) )
{
op->volume += eg_inc[op->eg_sel_rs + ((ym2413.eg_cnt>>op->eg_sh_rs)&15)];
if ( op->volume >= MAX_ATT_INDEX )
if ( (op->volume & ~3) == (MAX_ATT_INDEX & ~3) ) /* envelope level lowest 2 bits are ignored by the comparator */
{
op->volume = MAX_ATT_INDEX;
op->state = EG_OFF;
}
}
@ -700,22 +697,20 @@ INLINE void advance(void)
if ( !(ym2413.eg_cnt & ((1<<op->eg_sh_rr)-1) ) )
{
op->volume += eg_inc[op->eg_sel_rr + ((ym2413.eg_cnt>>op->eg_sh_rr)&15)];
if ( op->volume >= MAX_ATT_INDEX )
if ( (op->volume & ~3) == (MAX_ATT_INDEX & ~3) ) /* envelope level lowest 2 bits are ignored by the comparator */
{
op->volume = MAX_ATT_INDEX;
op->state = EG_OFF;
}
}
}
}
else /* percussive mode */
else /* percussive mode */
{
if ( !(ym2413.eg_cnt & ((1<<op->eg_sh_rs)-1) ) )
{
op->volume += eg_inc[op->eg_sel_rs + ((ym2413.eg_cnt>>op->eg_sh_rs)&15)];
if ( op->volume >= MAX_ATT_INDEX )
if ( (op->volume & ~3) == (MAX_ATT_INDEX & ~3) ) /* envelope level lowest 2 bits are ignored by the comparator */
{
op->volume = MAX_ATT_INDEX;
op->state = EG_OFF;
}
}
@ -723,8 +718,12 @@ INLINE void advance(void)
}
break;
default:
break;
case EG_OFF: /* envelope off */
op->volume = MAX_ATT_INDEX;
break;
default:
break;
}
}
}