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sn76496: simplify writes

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This commit is contained in:
notaz 2017-09-30 18:14:20 +03:00
parent 4f2cdbf551
commit 5103774f6d
1 changed files with 39 additions and 81 deletions
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120
pico/sound/sn76496.c
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@ -73,96 +73,54 @@ int *sn76496_regs;
void SN76496Write(int data)
{
struct SN76496 *R = &ono_sn;
int n;
int n, r, c;
/* update the output buffer before changing the registers */
//stream_update(R->Channel,0);
r = R->LastRegister;
if (data & 0x80)
{
int r = (data & 0x70) >> 4;
int c = r/2;
r = R->LastRegister = (data & 0x70) >> 4;
c = r / 2;
R->LastRegister = r;
R->Register[r] = (R->Register[r] & 0x3f0) | (data & 0x0f);
switch (r)
{
case 0: /* tone 0 : frequency */
case 2: /* tone 1 : frequency */
case 4: /* tone 2 : frequency */
R->Period[c] = R->UpdateStep * R->Register[r];
if (R->Period[c] == 0) R->Period[c] = R->UpdateStep;
if (r == 4)
{
/* update noise shift frequency */
if ((R->Register[6] & 0x03) == 0x03)
R->Period[3] = 2 * R->Period[2];
}
break;
case 1: /* tone 0 : volume */
case 3: /* tone 1 : volume */
case 5: /* tone 2 : volume */
case 7: /* noise : volume */
R->Volume[c] = R->VolTable[data & 0x0f];
break;
case 6: /* noise : frequency, mode */
{
int n = R->Register[6];
R->NoiseFB = (n & 4) ? FB_WNOISE : FB_PNOISE;
n &= 3;
/* N/512,N/1024,N/2048,Tone #3 output */
R->Period[3] = ((n&3) == 3) ? 2 * R->Period[2] : (R->UpdateStep << (5+(n&3)));
/* reset noise shifter */
R->RNG = NG_PRESET;
R->Output[3] = R->RNG & 1;
}
break;
}
}
if (!(data & 0x80) && (r == 0 || r == 2 || r == 4))
// data byte (tone only)
R->Register[r] = (R->Register[r] & 0x0f) | ((data & 0x3f) << 4);
else
R->Register[r] = (R->Register[r] & 0x3f0) | (data & 0x0f);
data = R->Register[r];
switch (r)
{
int r = R->LastRegister;
int c = r/2;
case 0: /* tone 0 : frequency */
case 2: /* tone 1 : frequency */
case 4: /* tone 2 : frequency */
R->Period[c] = R->UpdateStep * data;
if (R->Period[c] == 0) R->Period[c] = R->UpdateStep;
if (r == 4)
{
/* update noise shift frequency */
if ((R->Register[6] & 0x03) == 0x03)
R->Period[3] = 2 * R->Period[2];
}
break;
case 1: /* tone 0 : volume */
case 3: /* tone 1 : volume */
case 5: /* tone 2 : volume */
case 7: /* noise : volume */
R->Volume[c] = R->VolTable[data & 0x0f];
break;
case 6: /* noise : frequency, mode */
n = data;
R->NoiseFB = (n & 4) ? FB_WNOISE : FB_PNOISE;
n &= 3;
/* N/512,N/1024,N/2048,Tone #3 output */
R->Period[3] = (n == 3) ? 2 * R->Period[2] : (R->UpdateStep << (5 + n));
switch (r)
{
case 0: /* tone 0 : frequency */
case 2: /* tone 1 : frequency */
case 4: /* tone 2 : frequency */
R->Register[r] = (R->Register[r] & 0x0f) | ((data & 0x3f) << 4);
R->Period[c] = R->UpdateStep * R->Register[r];
if (R->Period[c] == 0) R->Period[c] = R->UpdateStep;
if (r == 4)
{
/* update noise shift frequency */
if ((R->Register[6] & 0x03) == 0x03)
R->Period[3] = 2 * R->Period[2];
}
break;
case 1: /* tone 0 : volume */
case 3: /* tone 1 : volume */
case 5: /* tone 2 : volume */
case 7: /* noise : volume */
R->Volume[c] = R->VolTable[data & 0x0f];
R->Register[r] = (R->Register[r] & 0x3f0) | (data & 0x0f);
break;
case 6: /* noise : frequency, mode */
{
R->Register[r] = (R->Register[r] & 0x3f0) | (data & 0x0f);
n = R->Register[6];
R->NoiseFB = (n & 4) ? FB_WNOISE : FB_PNOISE;
n &= 3;
/* N/512,N/1024,N/2048,Tone #3 output */
R->Period[3] = ((n&3) == 3) ? 2 * R->Period[2] : (R->UpdateStep << (5+(n&3)));
/* reset noise shifter */
R->RNG = NG_PRESET;
R->Output[3] = R->RNG & 1;
}
break;
}
/* reset noise shifter */
R->RNG = NG_PRESET;
R->Output[3] = R->RNG & 1;
break;
}
}