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[Core/Sound] fixed EG counter loopback behavior (verified on real YM3438 die by nukez)

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ekeeke 2017-09-26 10:25:48 +02:00 committed by GitHub
parent e215268169
commit 3d8bd155a7
1 changed files with 19 additions and 9 deletions
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26
core/sound/ym2612.c
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@ -24,6 +24,10 @@
/*
** CHANGELOG:
**
** 26-09-2017 Eke-Eke (Genesis Plus GX):
** - fixed EG counter loopback behavior (verified on YM3438 die)
** - reverted changes to EG rates 2-7 increment values
**
** 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)
** - fixed Timer B overflow handling
@ -240,12 +244,11 @@ O(18),O(18),O(18),O(18),O(18),O(18),O(18),O(18),
/* rates 00-11 */
/*
O( 0),O( 1),O( 2),O( 3),
O( 0),O( 1),O( 2),O( 3),
O( 0),O( 1)
*/
O(18),O(18),O( 0),O( 0),
O( 0),O( 0),O( 2),O( 2), /* Nemesis's tests */
O(18),O(18), /* from Nemesis's tests on real YM2612 hardware */
O( 2),O( 3),
O( 0),O( 1),O( 2),O( 3),
O( 0),O( 1),O( 2),O( 3),
O( 0),O( 1),O( 2),O( 3),
O( 0),O( 1),O( 2),O( 3),
@ -2045,14 +2048,21 @@ void YM2612Update(int *buffer, int length)
/* advance LFO */
advance_lfo();
/* advance envelope generator */
ym2612.OPN.eg_timer ++;
/* EG is updated every 3 samples */
ym2612.OPN.eg_timer++;
if (ym2612.OPN.eg_timer >= 3)
{
/* reset EG timer */
ym2612.OPN.eg_timer = 0;
/* increment EG counter */
ym2612.OPN.eg_cnt++;
/* EG counter is 12-bit only and zero value is skipped (verified on real hardware) */
if (ym2612.OPN.eg_cnt == 4096)
ym2612.OPN.eg_cnt = 1;
/* advance envelope generator */
advance_eg_channels(&ym2612.CH[0], ym2612.OPN.eg_cnt);
}