***************************************************************************/
-//
+//
// From mame.txt (http://www.mame.net/readme.html)
-//
+//
// VI. Reuse of Source Code
// --------------------------
// This chapter might not apply to specific portions of MAME (e.g. CPU
// However, given the amount of time and energy it took to collect this
// information, if you find new information we would appreciate if you made it
// freely available as well.
-//
+//
-// JLH: Removed MAME specific crap
+// JLH: Commented out MAME specific crap
-#include <string.h> // for memset()
#include "ay8910.h"
+#include <string.h> // for memset()
-///////////////////////////////////////////////////////////
-// typedefs & dummy funcs to allow MAME code to compile:
-//
-//typedef UINT8 (*mem_read_handler)(UINT32);
-//typedef void (*mem_write_handler)(UINT32, UINT8);
-//
-//static void logerror(char* psz, ...)
-//{
-//}
-//
-//static unsigned short activecpu_get_pc()
-//{
-// return 0;
-//}
-//
-//
-///////////////////////////////////////////////////////////
-
-#define MAX_OUTPUT 0x7fff
+#define MAX_OUTPUT 0x7FFF
// See AY8910_set_clock() for definition of STEP
#define STEP 0x8000
-//This is not used at all...
-//static int num = 0, ym_num = 0;
-
struct AY8910
{
int Channel;
unsigned char Regs[16];
int lastEnable;
unsigned int UpdateStep;
- int PeriodA,PeriodB,PeriodC,PeriodN,PeriodE;
- int CountA,CountB,CountC,CountN,CountE;
- unsigned int VolA,VolB,VolC,VolE;
- unsigned char EnvelopeA,EnvelopeB,EnvelopeC;
- unsigned char OutputA,OutputB,OutputC,OutputN;
+ int PeriodA, PeriodB, PeriodC, PeriodN, PeriodE;
+ int CountA, CountB, CountC, CountN, CountE;
+ unsigned int VolA, VolB, VolC, VolE;
+ unsigned char EnvelopeA, EnvelopeB, EnvelopeC;
+ unsigned char OutputA, OutputB, OutputC, OutputN;
signed char CountEnv;
- unsigned char Hold,Alternate,Attack,Holding;
+ unsigned char Hold, Alternate, Attack, Holding;
int RNG;
unsigned int VolTable[32];
};
static struct AY8910 AYPSG[MAX_8910]; /* array of PSG's */
-
void _AYWriteReg(int n, int r, int v)
{
struct AY8910 *PSG = &AYPSG[n];
int old;
-
PSG->Regs[r] = v;
- /* A note about the period of tones, noise and envelope: for speed reasons,*/
- /* we count down from the period to 0, but careful studies of the chip */
- /* output prove that it instead counts up from 0 until the counter becomes */
- /* greater or equal to the period. This is an important difference when the*/
- /* program is rapidly changing the period to modulate the sound. */
- /* To compensate for the difference, when the period is changed we adjust */
- /* our internal counter. */
- /* Also, note that period = 0 is the same as period = 1. This is mentioned */
- /* in the YM2203 data sheets. However, this does NOT apply to the Envelope */
- /* period. In that case, period = 0 is half as period = 1. */
- switch( r )
+ /* A note about the period of tones, noise and envelope: for speed reasons, *
+ * we count down from the period to 0, but careful studies of the chip *
+ * output prove that it instead counts up from 0 until the counter becomes *
+ * greater or equal to the period. This is an important difference when the *
+ * program is rapidly changing the period to modulate the sound. *
+ * To compensate for the difference, when the period is changed we adjust *
+ * our internal counter. *
+ * Also, note that period = 0 is the same as period = 1. This is mentioned *
+ * in the YM2203 data sheets. However, this does NOT apply to the Envelope *
+ * period. In that case, period = 0 is half as period = 1. */
+ switch (r)
{
case AY_AFINE:
case AY_ACOARSE:
- PSG->Regs[AY_ACOARSE] &= 0x0f;
+ PSG->Regs[AY_ACOARSE] &= 0x0F;
old = PSG->PeriodA;
PSG->PeriodA = (PSG->Regs[AY_AFINE] + 256 * PSG->Regs[AY_ACOARSE]) * PSG->UpdateStep;
- if (PSG->PeriodA == 0) PSG->PeriodA = PSG->UpdateStep;
+
+ if (PSG->PeriodA == 0)
+ PSG->PeriodA = PSG->UpdateStep;
+
PSG->CountA += PSG->PeriodA - old;
- if (PSG->CountA <= 0) PSG->CountA = 1;
+
+ if (PSG->CountA <= 0)
+ PSG->CountA = 1;
break;
case AY_BFINE:
case AY_BCOARSE:
- PSG->Regs[AY_BCOARSE] &= 0x0f;
+ PSG->Regs[AY_BCOARSE] &= 0x0F;
old = PSG->PeriodB;
PSG->PeriodB = (PSG->Regs[AY_BFINE] + 256 * PSG->Regs[AY_BCOARSE]) * PSG->UpdateStep;
- if (PSG->PeriodB == 0) PSG->PeriodB = PSG->UpdateStep;
+
+ if (PSG->PeriodB == 0)
+ PSG->PeriodB = PSG->UpdateStep;
+
PSG->CountB += PSG->PeriodB - old;
- if (PSG->CountB <= 0) PSG->CountB = 1;
+
+ if (PSG->CountB <= 0)
+ PSG->CountB = 1;
break;
case AY_CFINE:
case AY_CCOARSE:
- PSG->Regs[AY_CCOARSE] &= 0x0f;
+ PSG->Regs[AY_CCOARSE] &= 0x0F;
old = PSG->PeriodC;
PSG->PeriodC = (PSG->Regs[AY_CFINE] + 256 * PSG->Regs[AY_CCOARSE]) * PSG->UpdateStep;
- if (PSG->PeriodC == 0) PSG->PeriodC = PSG->UpdateStep;
+
+ if (PSG->PeriodC == 0)
+ PSG->PeriodC = PSG->UpdateStep;
+
PSG->CountC += PSG->PeriodC - old;
- if (PSG->CountC <= 0) PSG->CountC = 1;
+
+ if (PSG->CountC <= 0)
+ PSG->CountC = 1;
break;
case AY_NOISEPER:
- PSG->Regs[AY_NOISEPER] &= 0x1f;
+ PSG->Regs[AY_NOISEPER] &= 0x1F;
old = PSG->PeriodN;
PSG->PeriodN = PSG->Regs[AY_NOISEPER] * PSG->UpdateStep;
- if (PSG->PeriodN == 0) PSG->PeriodN = PSG->UpdateStep;
+
+ if (PSG->PeriodN == 0)
+ PSG->PeriodN = PSG->UpdateStep;
+
PSG->CountN += PSG->PeriodN - old;
- if (PSG->CountN <= 0) PSG->CountN = 1;
+
+ if (PSG->CountN <= 0)
+ PSG->CountN = 1;
break;
case AY_ENABLE:
if ((PSG->lastEnable == -1) ||
PSG->lastEnable = PSG->Regs[AY_ENABLE];
break;
case AY_AVOL:
- PSG->Regs[AY_AVOL] &= 0x1f;
+ PSG->Regs[AY_AVOL] &= 0x1F;
PSG->EnvelopeA = PSG->Regs[AY_AVOL] & 0x10;
PSG->VolA = PSG->EnvelopeA ? PSG->VolE : PSG->VolTable[PSG->Regs[AY_AVOL] ? PSG->Regs[AY_AVOL]*2+1 : 0];
break;
case AY_BVOL:
- PSG->Regs[AY_BVOL] &= 0x1f;
+ PSG->Regs[AY_BVOL] &= 0x1F;
PSG->EnvelopeB = PSG->Regs[AY_BVOL] & 0x10;
PSG->VolB = PSG->EnvelopeB ? PSG->VolE : PSG->VolTable[PSG->Regs[AY_BVOL] ? PSG->Regs[AY_BVOL]*2+1 : 0];
break;
case AY_CVOL:
- PSG->Regs[AY_CVOL] &= 0x1f;
+ PSG->Regs[AY_CVOL] &= 0x1F;
PSG->EnvelopeC = PSG->Regs[AY_CVOL] & 0x10;
PSG->VolC = PSG->EnvelopeC ? PSG->VolE : PSG->VolTable[PSG->Regs[AY_CVOL] ? PSG->Regs[AY_CVOL]*2+1 : 0];
break;
case AY_ECOARSE:
old = PSG->PeriodE;
PSG->PeriodE = ((PSG->Regs[AY_EFINE] + 256 * PSG->Regs[AY_ECOARSE])) * PSG->UpdateStep;
- if (PSG->PeriodE == 0) PSG->PeriodE = PSG->UpdateStep / 2;
+
+ if (PSG->PeriodE == 0)
+ PSG->PeriodE = PSG->UpdateStep / 2;
+
PSG->CountE += PSG->PeriodE - old;
- if (PSG->CountE <= 0) PSG->CountE = 1;
+
+ if (PSG->CountE <= 0)
+ PSG->CountE = 1;
break;
case AY_ESHAPE:
/* envelope shapes:
has twice the steps, happening twice as fast. Since the end result is
just a smoother curve, we always use the YM2149 behaviour.
*/
- PSG->Regs[AY_ESHAPE] &= 0x0f;
- PSG->Attack = (PSG->Regs[AY_ESHAPE] & 0x04) ? 0x1f : 0x00;
+ PSG->Regs[AY_ESHAPE] &= 0x0F;
+ PSG->Attack = (PSG->Regs[AY_ESHAPE] & 0x04) ? 0x1F : 0x00;
+
if ((PSG->Regs[AY_ESHAPE] & 0x08) == 0)
{
/* if Continue = 0, map the shape to the equivalent one which has Continue = 1 */
PSG->Hold = PSG->Regs[AY_ESHAPE] & 0x01;
PSG->Alternate = PSG->Regs[AY_ESHAPE] & 0x02;
}
+
PSG->CountE = PSG->PeriodE;
- PSG->CountEnv = 0x1f;
+ PSG->CountEnv = 0x1F;
PSG->Holding = 0;
PSG->VolE = PSG->VolTable[PSG->CountEnv ^ PSG->Attack];
- if (PSG->EnvelopeA) PSG->VolA = PSG->VolE;
- if (PSG->EnvelopeB) PSG->VolB = PSG->VolE;
- if (PSG->EnvelopeC) PSG->VolC = PSG->VolE;
+
+ if (PSG->EnvelopeA)
+ PSG->VolA = PSG->VolE;
+
+ if (PSG->EnvelopeB)
+ PSG->VolB = PSG->VolE;
+
+ if (PSG->EnvelopeC)
+ PSG->VolC = PSG->VolE;
break;
case AY_PORTA:
if (PSG->Regs[AY_ENABLE] & 0x40)
// NB. This should be called at twice the 6522 IRQ rate or (eg) 60Hz if no IRQ.
void AY8910Update(int chip, int16 ** buffer, int length) // [TC: Removed static]
{
- struct AY8910 *PSG = &AYPSG[chip];
- INT16 *buf1,*buf2,*buf3;
+ struct AY8910 * PSG = &AYPSG[chip];
+ int16 * buf1, * buf2, * buf3;
int outn;
buf1 = buffer[0];
buf2 = buffer[1];
buf3 = buffer[2];
-
- /* The 8910 has three outputs, each output is the mix of one of the three */
- /* tone generators and of the (single) noise generator. The two are mixed */
- /* BEFORE going into the DAC. The formula to mix each channel is: */
- /* (ToneOn | ToneDisable) & (NoiseOn | NoiseDisable). */
- /* Note that this means that if both tone and noise are disabled, the output */
- /* is 1, not 0, and can be modulated changing the volume. */
-
-
- /* If the channels are disabled, set their output to 1, and increase the */
- /* counter, if necessary, so they will not be inverted during this update. */
- /* Setting the output to 1 is necessary because a disabled channel is locked */
- /* into the ON state (see above); and it has no effect if the volume is 0. */
- /* If the volume is 0, increase the counter, but don't touch the output. */
+ /* The 8910 has three outputs, each output is the mix of one of the three *
+ * tone generators and of the (single) noise generator. The two are mixed *
+ * BEFORE going into the DAC. The formula to mix each channel is: *
+ * (ToneOn | ToneDisable) & (NoiseOn | NoiseDisable). *
+ * Note that this means that if both tone and noise are disabled, the output *
+ * is 1, not 0, and can be modulated changing the volume. *
+ * *
+ * If the channels are disabled, set their output to 1, and increase the *
+ * counter, if necessary, so they will not be inverted during this update. *
+ * Setting the output to 1 is necessary because a disabled channel is locked *
+ * into the ON state (see above); and it has no effect if the volume is 0. *
+ * If the volume is 0, increase the counter, but don't touch the output. */
if (PSG->Regs[AY_ENABLE] & 0x01)
{
- if (PSG->CountA <= length*STEP) PSG->CountA += length*STEP;
+ if (PSG->CountA <= length * STEP)
+ PSG->CountA += length * STEP;
+
PSG->OutputA = 1;
}
else if (PSG->Regs[AY_AVOL] == 0)
{
- /* note that I do count += length, NOT count = length + 1. You might think */
- /* it's the same since the volume is 0, but doing the latter could cause */
- /* interferencies when the program is rapidly modulating the volume. */
- if (PSG->CountA <= length*STEP) PSG->CountA += length*STEP;
+ /* note that I do count += length, NOT count = length + 1. You might think *
+ * it's the same since the volume is 0, but doing the latter could cause *
+ * interferencies when the program is rapidly modulating the volume. */
+ if (PSG->CountA <= length * STEP)
+ PSG->CountA += length * STEP;
}
+
if (PSG->Regs[AY_ENABLE] & 0x02)
{
- if (PSG->CountB <= length*STEP) PSG->CountB += length*STEP;
+ if (PSG->CountB <= length * STEP)
+ PSG->CountB += length * STEP;
+
PSG->OutputB = 1;
}
else if (PSG->Regs[AY_BVOL] == 0)
{
- if (PSG->CountB <= length*STEP) PSG->CountB += length*STEP;
+ if (PSG->CountB <= length * STEP)
+ PSG->CountB += length * STEP;
}
+
if (PSG->Regs[AY_ENABLE] & 0x04)
{
- if (PSG->CountC <= length*STEP) PSG->CountC += length*STEP;
+ if (PSG->CountC <= length * STEP)
+ PSG->CountC += length * STEP;
+
PSG->OutputC = 1;
}
else if (PSG->Regs[AY_CVOL] == 0)
{
- if (PSG->CountC <= length*STEP) PSG->CountC += length*STEP;
+ if (PSG->CountC <= length * STEP)
+ PSG->CountC += length * STEP;
}
- /* for the noise channel we must not touch OutputN - it's also not necessary */
- /* since we use outn. */
+ /* for the noise channel we must not touch OutputN - it's also not necessary *
+ * since we use outn. */
if ((PSG->Regs[AY_ENABLE] & 0x38) == 0x38) /* all off */
- if (PSG->CountN <= length*STEP) PSG->CountN += length*STEP;
+ if (PSG->CountN <= length * STEP)
+ PSG->CountN += length * STEP;
outn = (PSG->OutputN | PSG->Regs[AY_ENABLE]);
-
/* buffering loop */
while (length)
{
- int vola,volb,volc;
+ int vola, volb, volc;
int left;
-
- /* vola, volb and volc keep track of how long each square wave stays */
- /* in the 1 position during the sample period. */
+ /* vola, volb and volc keep track of how long each square wave stays *
+ * in the 1 position during the sample period. */
vola = volb = volc = 0;
left = STEP;
{
int nextevent;
-
- if (PSG->CountN < left) nextevent = PSG->CountN;
- else nextevent = left;
+ if (PSG->CountN < left)
+ nextevent = PSG->CountN;
+ else
+ nextevent = left;
if (outn & 0x08)
{
- if (PSG->OutputA) vola += PSG->CountA;
+ if (PSG->OutputA)
+ vola += PSG->CountA;
+
PSG->CountA -= nextevent;
- /* PeriodA is the half period of the square wave. Here, in each */
- /* loop I add PeriodA twice, so that at the end of the loop the */
- /* square wave is in the same status (0 or 1) it was at the start. */
- /* vola is also incremented by PeriodA, since the wave has been 1 */
- /* exactly half of the time, regardless of the initial position. */
- /* If we exit the loop in the middle, OutputA has to be inverted */
- /* and vola incremented only if the exit status of the square */
- /* wave is 1. */
+ /* PeriodA is the half period of the square wave. Here, in each *
+ * loop I add PeriodA twice, so that at the end of the loop the *
+ * square wave is in the same status (0 or 1) it was at the start. *
+ * vola is also incremented by PeriodA, since the wave has been 1 *
+ * exactly half of the time, regardless of the initial position. *
+ * If we exit the loop in the middle, OutputA has to be inverted *
+ * and vola incremented only if the exit status of the square *
+ * wave is 1. */
while (PSG->CountA <= 0)
{
PSG->CountA += PSG->PeriodA;
+
if (PSG->CountA > 0)
{
PSG->OutputA ^= 1;
- if (PSG->OutputA) vola += PSG->PeriodA;
+
+ if (PSG->OutputA)
+ vola += PSG->PeriodA;
break;
}
+
PSG->CountA += PSG->PeriodA;
vola += PSG->PeriodA;
}
- if (PSG->OutputA) vola -= PSG->CountA;
+
+ if (PSG->OutputA)
+ vola -= PSG->CountA;
}
else
{
while (PSG->CountA <= 0)
{
PSG->CountA += PSG->PeriodA;
+
if (PSG->CountA > 0)
{
PSG->OutputA ^= 1;
break;
}
+
PSG->CountA += PSG->PeriodA;
}
}
if (outn & 0x10)
{
- if (PSG->OutputB) volb += PSG->CountB;
+ if (PSG->OutputB)
+ volb += PSG->CountB;
+
PSG->CountB -= nextevent;
+
while (PSG->CountB <= 0)
{
PSG->CountB += PSG->PeriodB;
+
if (PSG->CountB > 0)
{
PSG->OutputB ^= 1;
- if (PSG->OutputB) volb += PSG->PeriodB;
+
+ if (PSG->OutputB)
+ volb += PSG->PeriodB;
break;
}
+
PSG->CountB += PSG->PeriodB;
volb += PSG->PeriodB;
}
- if (PSG->OutputB) volb -= PSG->CountB;
+
+ if (PSG->OutputB)
+ volb -= PSG->CountB;
}
else
{
PSG->CountB -= nextevent;
+
while (PSG->CountB <= 0)
{
PSG->CountB += PSG->PeriodB;
+
if (PSG->CountB > 0)
{
PSG->OutputB ^= 1;
break;
}
+
PSG->CountB += PSG->PeriodB;
}
}
if (outn & 0x20)
{
- if (PSG->OutputC) volc += PSG->CountC;
+ if (PSG->OutputC)
+ volc += PSG->CountC;
+
PSG->CountC -= nextevent;
+
while (PSG->CountC <= 0)
{
PSG->CountC += PSG->PeriodC;
+
if (PSG->CountC > 0)
{
PSG->OutputC ^= 1;
- if (PSG->OutputC) volc += PSG->PeriodC;
+
+ if (PSG->OutputC)
+ volc += PSG->PeriodC;
break;
}
+
PSG->CountC += PSG->PeriodC;
volc += PSG->PeriodC;
}
- if (PSG->OutputC) volc -= PSG->CountC;
+
+ if (PSG->OutputC)
+ volc -= PSG->CountC;
}
else
{
PSG->CountC -= nextevent;
+
while (PSG->CountC <= 0)
{
PSG->CountC += PSG->PeriodC;
+
if (PSG->CountC > 0)
{
PSG->OutputC ^= 1;
break;
}
+
PSG->CountC += PSG->PeriodC;
}
}
PSG->CountN -= nextevent;
+
if (PSG->CountN <= 0)
{
/* Is noise output going to change? */
- if ((PSG->RNG + 1) & 2) /* (bit0^bit1)? */
+ if ((PSG->RNG + 1) & 0x00002) /* (bit0^bit1)? */
{
PSG->OutputN = ~PSG->OutputN;
outn = (PSG->OutputN | PSG->Regs[AY_ENABLE]);
}
- /* The Random Number Generator of the 8910 is a 17-bit shift */
- /* register. The input to the shift register is bit0 XOR bit3 */
- /* (bit0 is the output). This was verified on AY-3-8910 and YM2149 chips. */
+ /* The Random Number Generator of the 8910 is a 17-bit shift *
+ * register. The input to the shift register is bit0 XOR bit3 *
+ * (bit0 is the output). This was verified on AY-3-8910 and *
+ * YM2149 chips. *
+ * *
+ * The following is a fast way to compute bit17 = bit0^bit3. *
+ * Instead of doing all the logic operations, we only check *
+ * bit0, relying on the fact that after three shifts of the *
+ * register, what now is bit3 will become bit0, and will *
+ * invert, if necessary, bit14, which previously was bit17. */
+ if (PSG->RNG & 0x00001)
+ PSG->RNG ^= 0x24000; /* This version is called the "Galois configuration". */
- /* The following is a fast way to compute bit17 = bit0^bit3. */
- /* Instead of doing all the logic operations, we only check */
- /* bit0, relying on the fact that after three shifts of the */
- /* register, what now is bit3 will become bit0, and will */
- /* invert, if necessary, bit14, which previously was bit17. */
- if (PSG->RNG & 1) PSG->RNG ^= 0x24000; /* This version is called the "Galois configuration". */
PSG->RNG >>= 1;
PSG->CountN += PSG->PeriodN;
}
left -= nextevent;
- } while (left > 0);
+ }
+ while (left > 0);
/* update envelope */
if (PSG->Holding == 0)
{
PSG->CountE -= STEP;
+
if (PSG->CountE <= 0)
{
do
{
PSG->CountEnv--;
PSG->CountE += PSG->PeriodE;
- } while (PSG->CountE <= 0);
+ }
+ while (PSG->CountE <= 0);
/* check envelope current position */
if (PSG->CountEnv < 0)
if (PSG->Hold)
{
if (PSG->Alternate)
- PSG->Attack ^= 0x1f;
+ PSG->Attack ^= 0x1F;
+
PSG->Holding = 1;
PSG->CountEnv = 0;
}
else
{
- /* if CountEnv has looped an odd number of times (usually 1), */
- /* invert the output. */
+ /* if CountEnv has looped an odd number of times (usually 1), *
+ * invert the output. */
if (PSG->Alternate && (PSG->CountEnv & 0x20))
- PSG->Attack ^= 0x1f;
+ PSG->Attack ^= 0x1F;
- PSG->CountEnv &= 0x1f;
+ PSG->CountEnv &= 0x1F;
}
}
PSG->VolE = PSG->VolTable[PSG->CountEnv ^ PSG->Attack];
/* reload volume */
- if (PSG->EnvelopeA) PSG->VolA = PSG->VolE;
- if (PSG->EnvelopeB) PSG->VolB = PSG->VolE;
- if (PSG->EnvelopeC) PSG->VolC = PSG->VolE;
+ if (PSG->EnvelopeA)
+ PSG->VolA = PSG->VolE;
+
+ if (PSG->EnvelopeB)
+ PSG->VolB = PSG->VolE;
+
+ if (PSG->EnvelopeC)
+ PSG->VolC = PSG->VolE;
}
}
*(buf1++) = (vola * PSG->VolA) / STEP;
*(buf2++) = (volb * PSG->VolB) / STEP;
*(buf3++) = (volc * PSG->VolC) / STEP;
-#else
+#else // [Tom's code...]
// Output PCM wave [-32768...32767] instead of MAME's voltage level [0...32767]
// - This allows for better s/w mixing
- if(PSG->VolA)
+ if (PSG->VolA)
{
- if(vola)
+ if (vola)
*(buf1++) = (vola * PSG->VolA) / STEP;
else
- *(buf1++) = - (int) PSG->VolA;
+ *(buf1++) = -(int)PSG->VolA;
}
else
- {
*(buf1++) = 0;
- }
-
- //
- if(PSG->VolB)
+ if (PSG->VolB)
{
- if(volb)
+ if (volb)
*(buf2++) = (volb * PSG->VolB) / STEP;
else
- *(buf2++) = - (int) PSG->VolB;
+ *(buf2++) = -(int)PSG->VolB;
}
else
- {
*(buf2++) = 0;
- }
-
- //
- if(PSG->VolC)
+ if (PSG->VolC)
{
- if(volc)
+ if (volc)
*(buf3++) = (volc * PSG->VolC) / STEP;
else
- *(buf3++) = - (int) PSG->VolC;
+ *(buf3++) = -(int)PSG->VolC;
}
else
- {
*(buf3++) = 0;
- }
#endif
-
length--;
}
}
-static void AY8910_set_clock(int chip,int clock)
+static void AY8910_set_clock(int chip, int clock)
{
- struct AY8910 *PSG = &AYPSG[chip];
-
- /* the step clock for the tone and noise generators is the chip clock */
- /* divided by 8; for the envelope generator of the AY-3-8910, it is half */
- /* that much (clock/16), but the envelope of the YM2149 goes twice as */
- /* fast, therefore again clock/8. */
- /* Here we calculate the number of steps which happen during one sample */
- /* at the given sample rate. No. of events = sample rate / (clock/8). */
- /* STEP is a multiplier used to turn the fraction into a fixed point */
- /* number. */
- PSG->UpdateStep = (unsigned int) (((double)STEP * PSG->SampleRate * 8 + clock/2) / clock); // [TC: unsigned int cast]
+ struct AY8910 * PSG = &AYPSG[chip];
+
+ /* The step clock for the tone and noise generators is the chip clock *
+ * divided by 8; for the envelope generator of the AY-3-8910, it is half *
+ * that much (clock/16), but the envelope of the YM2149 goes twice as *
+ * fast, therefore again clock/8. *
+ * Here we calculate the number of steps which happen during one sample *
+ * at the given sample rate. No. of events = sample rate / (clock/8). *
+ * STEP is a multiplier used to turn the fraction into a fixed point *
+ * number. */
+ PSG->UpdateStep = (unsigned int)(((double)STEP * PSG->SampleRate * 8 + clock / 2) / clock); // [TC: unsigned int cast]
}
static void build_mixer_table(int chip)
{
- struct AY8910 *PSG = &AYPSG[chip];
- int i;
- double out;
+ struct AY8910 * PSG = &AYPSG[chip];
-
- /* calculate the volume->voltage conversion table */
+ /* calculate the volume->voltage conversion table */
/* The AY-3-8910 has 16 levels, in a logarithmic scale (3dB per step) */
/* The YM2149 still has 16 levels for the tone generators, but 32 for */
- /* the envelope generator (1.5dB per step). */
- out = MAX_OUTPUT;
- for (i = 31;i > 0;i--)
- {
- PSG->VolTable[i] = (unsigned int) (out + 0.5); /* round to nearest */ // [TC: unsigned int cast]
+ /* the envelope generator (1.5dB per step). */
+ double out = MAX_OUTPUT;
+ for(int i=31; i>0; i--)
+ {
+ PSG->VolTable[i] = (unsigned int)(out + 0.5); /* round to nearest */ // [TC: unsigned int cast]
out /= 1.188502227; /* = 10 ^ (1.5/20) = 1.5dB */
}
+
PSG->VolTable[0] = 0;
}
void AY8910_reset(int chip)
{
int i;
- struct AY8910 *PSG = &AYPSG[chip];
+ struct AY8910 * PSG = &AYPSG[chip];
PSG->register_latch = 0;
PSG->RNG = 1;
PSG->OutputA = 0;
PSG->OutputB = 0;
PSG->OutputC = 0;
- PSG->OutputN = 0xff;
+ PSG->OutputN = 0xFF;
PSG->lastEnable = -1; /* force a write */
- for (i = 0;i < AY_PORTA;i++)
- _AYWriteReg(chip,i,0); /* AYWriteReg() uses the timer system; we cannot */
- /* call it at this time because the timer system */
- /* has not been initialized. */
+
+ for(i=0; i<AY_PORTA; i++)
+ _AYWriteReg(chip, i, 0); /* AYWriteReg() uses the timer system; we cannot */
+ /* call it at this time because the timer system */
+ /* has not been initialized. */
}
-//-------------------------------------
+// This stuff looks like Tom's code, so let's streamline and un-MSHungarianize this shit:
+// [DONE]
-void AY8910_InitAll(int nClock, int nSampleRate)
+void AY8910_InitAll(int clock, int sampleRate)
{
- for(int nChip=0; nChip<MAX_8910; nChip++)
+ for(int chip=0; chip<MAX_8910; chip++)
{
- struct AY8910 *PSG = &AYPSG[nChip];
-
- memset(PSG,0,sizeof(struct AY8910));
- PSG->SampleRate = nSampleRate;
+ struct AY8910 * PSG = &AYPSG[chip];
-// PSG->PortAread = NULL;
-// PSG->PortBread = NULL;
-// PSG->PortAwrite = NULL;
-// PSG->PortBwrite = NULL;
-
- AY8910_set_clock(nChip, nClock);
-
- build_mixer_table(nChip);
+ memset(PSG, 0, sizeof(struct AY8910));
+ PSG->SampleRate = sampleRate;
+ AY8910_set_clock(chip, clock);
+ build_mixer_table(chip);
}
}
-//-------------------------------------
-
-void AY8910_InitClock(int nClock)
+void AY8910_InitClock(int clock)
{
- for(int nChip=0; nChip<MAX_8910; nChip++)
- {
- AY8910_set_clock(nChip, nClock);
- }
+ for(int chip=0; chip<MAX_8910; chip++)
+ AY8910_set_clock(chip, clock);
}
-//-------------------------------------
-
-uint8 * AY8910_GetRegsPtr(uint16 nAyNum)
+uint8 * AY8910_GetRegsPtr(uint16 chipNum)
{
- if(nAyNum >= MAX_8910)
+ if (chipNum >= MAX_8910)
return NULL;
- return &AYPSG[nAyNum].Regs[0];
+ return &AYPSG[chipNum].Regs[0];
}