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speedup ymf278b_compute_envelope, and make note about reading fm regs

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This commit is contained in:
Michaël Banaan Ananas 2011-08-13 22:54:57 +00:00
parent ce1bc07076
commit 450320469d
1 changed files with 81 additions and 70 deletions
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63
src/emu/sound/ymf278b.c
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@ -233,7 +233,7 @@ static UINT32 ymf278_compute_decay_env_vol_step(YMF278BSlot *slot, int val)
// rate override with damping/pseudo reverb
if (slot->DAMP)
rate = 56; // datasheet says it's slightly curved though
rate = 56; // approximate, datasheet says it's slightly curved though
else if (slot->preverb && slot->env_vol > ((6*8)<<23))
{
// pseudo reverb starts at -18dB (6 in voltab)
@ -266,7 +266,10 @@ static void ymf278b_compute_freq_step(YMF278BSlot *slot)
static void ymf278b_compute_envelope(YMF278BSlot *slot)
{
if(slot->env_step == 0)
switch (slot->env_step)
{
// Attack
case 0:
{
// Attack
int rate = ymf278b_compute_rate(slot, slot->AR);
@ -279,70 +282,72 @@ static void ymf278b_compute_envelope(YMF278BSlot *slot)
LOG(("YMF278B: Attack skipped - "));
slot->env_vol = 0;
slot->env_step++;
// ..fall through
ymf278b_compute_envelope(slot);
}
else if (rate<4)
{
slot->env_vol_step = 0;
return;
}
else
{
// NOTE: attack rate is linear here, but datasheet shows a smooth curve
LOG(("YMF278B: Attack, val = %d, rate = %d, delay = %g\n", slot->AR, rate, ymf278_compute_attack_rate(rate)*1000.0));
slot->env_vol_step = ~((256U<<23) / ymf278_compute_attack_rate(rate));
return;
}
break;
}
if(slot->env_step == 1)
{
// Decay 1
case 1:
if(slot->DL)
{
LOG(("YMF278B: Decay step 1, dl=%d, val = %d rate = %d, delay = %g, PRVB = %d, DAMP = %d\n", slot->DL, slot->D1R, ymf278b_compute_rate(slot, slot->D1R), ymf278_compute_decay_rate(ymf278b_compute_rate(slot, slot->D1R))*1000.0, slot->preverb, slot->DAMP));
slot->env_vol_step = ymf278_compute_decay_env_vol_step(slot, slot->D1R);
slot->env_vol_lim = (slot->DL*8)<<23;
return;
}
else
slot->env_step++;
// ..fall through
}
if(slot->env_step == 2)
{
LOG(("YMF278B: Decay 1 skipped - "));
slot->env_step++;
ymf278b_compute_envelope(slot);
}
break;
// Decay 2
case 2:
LOG(("YMF278B: Decay step 2, val = %d, rate = %d, delay = %g, , PRVB = %d, DAMP = %d, current vol = %d\n", slot->D2R, ymf278b_compute_rate(slot, slot->D2R), ymf278_compute_decay_rate(ymf278b_compute_rate(slot, slot->D2R))*1000.0, slot->preverb, slot->DAMP, slot->env_vol >> 23));
slot->env_vol_step = ymf278_compute_decay_env_vol_step(slot, slot->D2R);
slot->env_vol_lim = 256U<<23;
return;
}
if(slot->env_step == 3)
{
break;
// Decay 2 reached -96dB
case 3:
LOG(("YMF278B: Voice cleared because of decay 2\n"));
slot->env_vol = 256U<<23;
slot->env_vol_step = 0;
slot->env_vol_lim = 0;
slot->active = 0;
return;
}
if(slot->env_step == 4)
{
break;
// Release
case 4:
LOG(("YMF278B: Release, val = %d, rate = %d, delay = %g, PRVB = %d, DAMP = %d\n", slot->RR, ymf278b_compute_rate(slot, slot->RR), ymf278_compute_decay_rate(ymf278b_compute_rate(slot, slot->RR))*1000.0, slot->preverb, slot->DAMP));
slot->env_vol_step = ymf278_compute_decay_env_vol_step(slot, slot->RR);
slot->env_vol_lim = 256U<<23;
return;
}
if(slot->env_step == 5)
{
break;
// Release reached -96dB
case 5:
LOG(("YMF278B: Release ends\n"));
slot->env_vol = 256U<<23;
slot->env_vol_step = 0;
slot->env_vol_lim = 0;
slot->active = 0;
return;
break;
default: break;
}
}
@ -857,7 +862,13 @@ READ8_DEVICE_HANDLER( ymf278b_r )
break;
}
// PCM regs (FM regs can't be read)
// FM regs can be read too (on contrary to what the datasheet says)
case 1:
case 3:
// but they're not implemented here yet
break;
// PCM regs
case 5:
// only accessible if NEW2 is set
if (~chip->exp & 2)