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fixed Savestates

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reverted SN76489 core changes (problem with Sonic 2 first level music, more investigations needed)
This commit is contained in:
ekeeke31 2009-08-05 07:02:09 +00:00
parent acdfb2dbee
commit e0737ff395
5 changed files with 303 additions and 277 deletions
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1
HISTORY.txt
View File

@ -6,7 +6,6 @@ Genesis Plus GX 1.4.0 (??/??/????) (Eke-Eke)
------ ------
* modified SN76489 cut-off frequency * modified SN76489 cut-off frequency
* implemented optimized SN76489 core which uses Blip Buffer linear synthesis (Noise Channel is now linear interpolated) (credits to Blargg)
* added an option to boost SN76489 Noise Channel * added an option to boost SN76489 Noise Channel
* removed outdated Gens YM2612 core * removed outdated Gens YM2612 core
* improved YM2612 core general accuracy (SSG-EG, CSM mode,...) (based upon Nemesis recent tests on real MD) * improved YM2612 core general accuracy (SSG-EG, CSM mode,...) (based upon Nemesis recent tests on real MD)

546
source/sound/sn76489.c
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@ -21,287 +21,141 @@
25/04/07 Eke-Eke (Genesis Plus GX) 25/04/07 Eke-Eke (Genesis Plus GX)
- Removed stereo GG support (unused) - Removed stereo GG support (unused)
- Rade SN76489_Update outputs 16bits mono samples - Made SN76489_Update outputs 16bits mono samples
- Replaced volume table with VGM plugin's one - Replaced volume table with VGM plugin's one
05/01/09 Eke-Eke (Genesis Plus GX) 05/01/09 Eke-Eke (Genesis Plus GX)
- Modified Cut-Off frequency (according to Steve Snake: http://www.smspower.org/forums/viewtopic.php?t=1746) - Modified Cut-Off frequency (according to Steve Snake: http://www.smspower.org/forums/viewtopic.php?t=1746)
25/05/09 Eke-Eke (Genesis Plus GX) 25/05/09 Eke-Eke (Genesis Plus GX)
- Removed multichip support (unused) - Removed multichip support (unused)
- Removed alternate volume table, panning & mute support (unused)
- Removed configurable Feedback and Shift Register Width (always use Sega ones)
- Added linear resampling using Blip Buffer (Blargg's implementation: http://www.smspower.org/forums/viewtopic.php?t=11376)
*/ */
#include "shared.h" #include "shared.h"
#include "blip.h"
#include <float.h>
/* Initial state of shift register */ #include <float.h> // for FLT_MIN
#define NoiseInitialState 0x8000 #include <string.h> // for memcpy
/* Value below which PSG does not output */ #define NoiseInitialState 0x8000 /* Initial state of shift register */
/*#define PSG_CUTOFF 0x6*/ //#define PSG_CUTOFF 0x6 /* Value below which PSG does not output */
#define PSG_CUTOFF 0x1 #define PSG_CUTOFF 0x1
static const int PSGVolumeValues[16] = /*
More testing is needed to find and confirm feedback patterns for
SN76489 variants and compatible chips.
*/
enum feedback_patterns {
FB_BBCMICRO = 0x8005, /* Texas Instruments TMS SN76489N (original) from BBC Micro computer */
FB_SC3000 = 0x0006, /* Texas Instruments TMS SN76489AN (rev. A) from SC-3000H computer */
FB_SEGAVDP = 0x0009, /* SN76489 clone in Sega's VDP chips (315-5124, 315-5246, 315-5313, Game Gear) */
};
enum sr_widths {
SRW_SC3000BBCMICRO = 15,
SRW_SEGAVDP = 16
};
enum volume_modes {
VOL_TRUNC = 0, /* Volume levels 13-15 are identical */
VOL_FULL = 1, /* Volume levels 13-15 are unique */
};
enum mute_values {
MUTE_ALLOFF = 0, /* All channels muted */
MUTE_TONE1 = 1, /* Tone 1 mute control */
MUTE_TONE2 = 2, /* Tone 2 mute control */
MUTE_TONE3 = 4, /* Tone 3 mute control */
MUTE_NOISE = 8, /* Noise mute control */
MUTE_ALLON = 15, /* All channels enabled */
};
typedef struct
{ {
int Mute; // per-channel muting
int VolumeArray;
int BoostNoise; // double noise volume when non-zero
/* Variables */
float Clock;
float dClock;
int PSGStereo;
int NumClocksForSample;
int WhiteNoiseFeedback;
int SRWidth;
/* PSG registers: */
int Registers[8]; /* Tone, vol x4 */
int LatchedRegister;
int NoiseShiftRegister;
int NoiseFreq; /* Noise channel signal generator frequency */
/* Output calculation variables */
int ToneFreqVals[4]; /* Frequency register values (counters) */
int ToneFreqPos[4]; /* Frequency channel flip-flops */
int Channels[4]; /* Value of each channel, before stereo is applied */
float IntermediatePos[4]; /* intermediate values used at boundaries between + and - (does not need double accuracy)*/
int panning[4]; /* fake stereo - 0..127..254 */
} SN76489_Context;
static const int PSGVolumeValues[2][16] = {
/* These values are taken from a real SMS2's output */ /* These values are taken from a real SMS2's output */
/*{892,892,892,760,623,497,404,323,257,198,159,123,96,75,60,0}, *//* I can't remember why 892... :P some scaling I did at some point */ {892,892,892,760,623,497,404,323,257,198,159,123,96,75,60,0}, /* I can't remember why 892... :P some scaling I did at some point */
/* these values are true volumes for 2dB drops at each step (multiply previous by 10^-0.1), normalised at 760 */ /* these values are true volumes for 2dB drops at each step (multiply previous by 10^-0.1), normalised at 760 */
1516,1205,957,760,603,479,381,303,240,191,152,120,96,76,60,0 {1516,1205,957,760,603,479,381,303,240,191,152,120,96,76,60,0}
}; };
static SN76489_Context SN76489; static SN76489_Context SN76489;
void SN76489_Init(int PSGClockValue, int SamplingRate) void SN76489_Init(int PSGClockValue, int SamplingRate)
{ {
SN76489_Context *p = &SN76489; SN76489_Context *p = &SN76489;
p->dClock=(float)PSGClockValue/16/SamplingRate;
/* SamplingRate*16 instead of PSGClockValue/16 since division would lose some SN76489_Config(MUTE_ALLON, VOL_FULL, FB_SEGAVDP, SRW_SEGAVDP, config.psgBoostNoise);
precision. blip_alloc doesn't care about the absolute sampling rate, just the SN76489_Reset();
ratio to clock rate. */
p->blip_buffer = blip_alloc(PSGClockValue, SamplingRate * 16, SamplingRate / 4);
SN76489_Reset();
} }
void SN76489_Reset() void SN76489_Reset(void)
{ {
SN76489_Context *p = &SN76489; SN76489_Context *p = &SN76489;
int i; int i;
for(i = 0; i <= 3; i++) p->PSGStereo = 0xFF;
{
/* Initialise PSG state */
p->Registers[2*i] = 1; /* tone freq=1 */
p->Registers[2*i+1] = 0xf; /* vol=off */
p->NoiseFreq = 0x10;
/* Set counters to 0 */ for(i = 0; i <= 3; i++)
p->ToneFreqVals[i] = 0; {
/* Initialise PSG state */
p->Registers[2*i] = 1; /* tone freq=1 */
p->Registers[2*i+1] = 0xf; /* vol=off */
p->NoiseFreq = 0x10;
/* Set flip-flops to 1 */ /* Set counters to 0 */
p->ToneFreqPos[i] = 1; p->ToneFreqVals[i] = 0;
/* Clear current amplitudes in Blip delta buffer */ /* Set flip-flops to 1 */
p->chan_amp[i] = 0; p->ToneFreqPos[i] = 1;
}
p->LatchedRegister=0; /* Set intermediate positions to do-not-use value */
p->IntermediatePos[i] = FLT_MIN;
/* Initialise noise generator */ /* Set panning to centre */
p->NoiseShiftRegister=NoiseInitialState; p->panning[0]=127;
}
p->LatchedRegister=0;
/* Initialise noise generator */
p->NoiseShiftRegister=NoiseInitialState;
/* Zero clock */
p->Clock=0;
/* Clear Blip delta buffer */
if (p->blip_buffer) blip_clear(p->blip_buffer);
} }
void SN76489_Shutdown(void) void SN76489_Shutdown(void)
{ {
SN76489_Context *p = &SN76489;
if (p->blip_buffer) blip_free(p->blip_buffer);
p->blip_buffer = NULL;
}
void SN76489_SetContext(uint8 *data)
{
memcpy(&SN76489, data, sizeof(SN76489_Context));
}
void SN76489_GetContext(uint8 *data)
{
memcpy(data, &SN76489, sizeof(SN76489_Context));
}
uint8 *SN76489_GetContextPtr(void)
{
return (uint8 *)&SN76489;
}
int SN76489_GetContextSize(void)
{
return sizeof(SN76489_Context);
}
void SN76489_Write(int data)
{
SN76489_Context *p = &SN76489;
if (data&0x80)
{
/* Latch/data byte %1 cc t dddd */
p->LatchedRegister=((data>>4)&0x07);
p->Registers[p->LatchedRegister] =
(p->Registers[p->LatchedRegister] & 0x3f0) | /* zero low 4 bits */
(data&0xf); /* and replace with data */
}
else
{
/* Data byte %0 - dddddd */
if (!(p->LatchedRegister%2)&&(p->LatchedRegister<5))
/* Tone register */
p->Registers[p->LatchedRegister]=
(p->Registers[p->LatchedRegister] & 0x00f) | /* zero high 6 bits */
((data&0x3f)<<4); /* and replace with data */
else
/* Other register */
p->Registers[p->LatchedRegister]=data&0x0f; /* Replace with data */
}
switch (p->LatchedRegister)
{
case 0:
case 2:
case 4: /* Tone channels */
/* Zero frequency changed to 1 to avoid div/0 */
if (p->Registers[p->LatchedRegister]==0) p->Registers[p->LatchedRegister]=1;
break;
case 6: /* Noise */
p->NoiseShiftRegister=NoiseInitialState; /* reset shift register */
p->NoiseFreq=0x10<<(p->Registers[6]&0x3); /* set noise signal generator frequency */
break;
}
}
/* Updates channel amplitude in delta buffer. Call whenever amplitude might have changed. */
static inline void UpdateChanAmplitude(SN76489_Context* chip, int i, int time)
{
/* Build stereo result into buffer */
int buffer = chip->Channels[i];
/* Update amplitudes in left and right buffers */
int delta = buffer - chip->chan_amp[i];
if (delta != 0)
{
chip->chan_amp[i] = buffer;
blip_add(chip->blip_buffer, time, delta);
}
}
/* Updates tone amplitude in delta buffer. Call whenever amplitude might have changed. */
static inline void UpdateToneAmplitude(SN76489_Context* chip, int i, int time)
{
/* Tone channels */
chip->Channels[i]= PSGVolumeValues[chip->Registers[2 * i + 1]] * chip->ToneFreqPos[i];
UpdateChanAmplitude(chip, i, time);
}
/* Updates noise amplitude in delta buffer. Call whenever amplitude might have changed. */
static inline void UpdateNoiseAmplitude(SN76489_Context* chip, int time)
{
/* Noise channel */
chip->Channels[3] = PSGVolumeValues[chip->Registers[7]] * ( chip->NoiseShiftRegister & 0x1 );
/* Boost noise volume */
chip->Channels[3] <<= chip->BoostNoise;
UpdateChanAmplitude(chip, 3, time);
}
/* Runs tone channel for clock_length clocks */
static inline void RunTone(SN76489_Context* chip, int i, int clock_length)
{
int time;
/* Update in case a register changed etc. */
UpdateToneAmplitude(chip, i, 0);
/* Time of next transition */
time = chip->ToneFreqVals[i];
/* Process any transitions that occur within clocks we're running */
while (time < clock_length)
{
if (chip->Registers[i*2]>PSG_CUTOFF) {
/* Flip the flip-flop */
chip->ToneFreqPos[i] = -chip->ToneFreqPos[i];
} else {
/* stuck value */
chip->ToneFreqPos[i] = 1;
}
UpdateToneAmplitude(chip, i, time);
/* Advance to time of next transition */
time += chip->Registers[i*2] + 1;
}
/* Calculate new value for register, now that next transition is past number of clocks we're running */
chip->ToneFreqVals[i] = time - clock_length;
}
/* Runs noise channel for clock_length clocks */
static inline void RunNoise(SN76489_Context* chip, int clock_length)
{
int time;
/* Noise channel: match to tone2 if in slave mode */
int NoiseFreq = chip->NoiseFreq;
if (NoiseFreq == 0x80)
{
NoiseFreq = chip->Registers[2*2];
chip->ToneFreqVals[3] = chip->ToneFreqVals[2];
}
/* Update in case a register changed etc. */
UpdateNoiseAmplitude(chip, 0);
/* Time of next transition */
time = chip->ToneFreqVals[3];
/* Process any transitions that occur within clocks we're running */
while ( time < clock_length )
{
/* Flip the flip-flop */
chip->ToneFreqPos[3] = -chip->ToneFreqPos[3];
if (chip->ToneFreqPos[3] == 1) {
/* On the positive edge of the square wave (only once per cycle) */
int Feedback;
if ( chip->Registers[6] & 0x4 ) {
/* White noise */
/* Calculate parity of fed-back bits for feedback */
/* Do some optimised calculations for common (known) feedback values */
/* If two bits fed back, I can do Feedback=(nsr & fb) && (nsr & fb ^ fb) */
/* since that's (one or more bits set) && (not all bits set) */
Feedback = ( ( chip->NoiseShiftRegister & FB_SEGAVDP)
&& ( (chip->NoiseShiftRegister & FB_SEGAVDP) ^ FB_SEGAVDP) );
} else /* Periodic noise */
Feedback=chip->NoiseShiftRegister&1;
chip->NoiseShiftRegister=(chip->NoiseShiftRegister>>1) | (Feedback << (SRW_SEGAVDP-1));
UpdateNoiseAmplitude(chip, time);
}
/* Advance to time of next transition */
time += NoiseFreq + 1;
}
/* Calculate new value for register, now that next transition is past number of clocks we're running */
chip->ToneFreqVals[3] = time - clock_length;
}
void SN76489_Update(INT16 *buffer, int length)
{
int i;
SN76489_Context *p = &SN76489;
/* Determine how many clocks we need to run until 'length' samples are available */
int clock_length = blip_clocks_needed(p->blip_buffer, length);
/* Run noise first, since it might use current value of third tone frequency counter */
RunNoise(p, clock_length);
/* Run tone channels */
for( i = 0; i <= 2; ++i )
RunTone(p, i, clock_length);
/* Read samples into output buffer */
blip_end_frame(p->blip_buffer,clock_length);
blip_read_samples(p->blip_buffer,buffer,length,0);
} }
void SN76489_BoostNoise(int boost) void SN76489_BoostNoise(int boost)
@ -309,3 +163,201 @@ void SN76489_BoostNoise(int boost)
SN76489.BoostNoise = boost; SN76489.BoostNoise = boost;
} }
void SN76489_Config(int mute, int volume, int feedback, int sr_width, int boost_noise)
{
SN76489_Context *p = &SN76489;
p->Mute = mute;
p->VolumeArray = volume;
p->WhiteNoiseFeedback = feedback;
p->SRWidth = sr_width;
p->BoostNoise = boost_noise;
}
void SN76489_SetContext(uint8 *data)
{
memcpy(&SN76489, data, sizeof(SN76489_Context));
}
void SN76489_GetContext(uint8 *data)
{
memcpy(data, &SN76489, sizeof(SN76489_Context));
}
uint8 *SN76489_GetContextPtr(void)
{
return (uint8 *)&SN76489;
}
int SN76489_GetContextSize(void)
{
return sizeof(SN76489_Context);
}
void SN76489_Write(int data)
{
SN76489_Context *p = &SN76489;
if (data&0x80) {
/* Latch/data byte %1 cc t dddd */
p->LatchedRegister=((data>>4)&0x07);
p->Registers[p->LatchedRegister]=
(p->Registers[p->LatchedRegister] & 0x3f0) /* zero low 4 bits */
| (data&0xf); /* and replace with data */
} else {
/* Data byte %0 - dddddd */
if (!(p->LatchedRegister%2)&&(p->LatchedRegister<5))
/* Tone register */
p->Registers[p->LatchedRegister]=
(p->Registers[p->LatchedRegister] & 0x00f) /* zero high 6 bits */
| ((data&0x3f)<<4); /* and replace with data */
else
/* Other register */
p->Registers[p->LatchedRegister]=data&0x0f; /* Replace with data */
}
switch (p->LatchedRegister) {
case 0:
case 2:
case 4: /* Tone channels */
if (p->Registers[p->LatchedRegister]==0) p->Registers[p->LatchedRegister]=1; /* Zero frequency changed to 1 to avoid div/0 */
break;
case 6: /* Noise */
p->NoiseShiftRegister=NoiseInitialState; /* reset shift register */
p->NoiseFreq=0x10<<(p->Registers[6]&0x3); /* set noise signal generator frequency */
break;
}
}
void SN76489_GGStereoWrite(int data)
{
SN76489_Context *p = &SN76489;
p->PSGStereo=data;
}
void SN76489_Update(INT16 *buffer, int length)
{
SN76489_Context *p = &SN76489;
int i, j;
for(j = 0; j < length; j++)
{
for (i=0;i<=2;++i)
if (p->IntermediatePos[i]!=FLT_MIN)
p->Channels[i]=(short)((p->Mute >> i & 0x1)*PSGVolumeValues[p->VolumeArray][p->Registers[2*i+1]]*p->IntermediatePos[i]);
else
p->Channels[i]=(p->Mute >> i & 0x1)*PSGVolumeValues[p->VolumeArray][p->Registers[2*i+1]]*p->ToneFreqPos[i];
p->Channels[3]=(short)((p->Mute >> 3 & 0x1)*PSGVolumeValues[p->VolumeArray][p->Registers[7]]*(p->NoiseShiftRegister & 0x1));
if (p->BoostNoise) p->Channels[3]<<=1; /* double noise volume */
buffer[j] =0;
for (i=0;i<=3;++i) buffer[j] += p->Channels[i];
p->Clock+=p->dClock;
p->NumClocksForSample=(int)p->Clock; /* truncates */
p->Clock-=p->NumClocksForSample; /* remove integer part */
/* Looks nicer in Delphi... */
/* Clock:=Clock+p->dClock; */
/* NumClocksForSample:=Trunc(Clock); */
/* Clock:=Frac(Clock); */
/* Decrement tone channel counters */
for (i=0;i<=2;++i)
p->ToneFreqVals[i]-=p->NumClocksForSample;
/* Noise channel: match to tone2 or decrement its counter */
if (p->NoiseFreq==0x80) p->ToneFreqVals[3]=p->ToneFreqVals[2];
else p->ToneFreqVals[3]-=p->NumClocksForSample;
/* Tone channels: */
for (i=0;i<=2;++i) {
if (p->ToneFreqVals[i]<=0) { /* If it gets below 0... */
if (p->Registers[i*2]>PSG_CUTOFF) {
/* Calculate how much of the sample is + and how much is - */
/* Go to floating point and include the clock fraction for extreme accuracy :D */
/* Store as long int, maybe it's faster? I'm not very good at this */
p->IntermediatePos[i]=(p->NumClocksForSample-p->Clock+2*p->ToneFreqVals[i])*p->ToneFreqPos[i]/(p->NumClocksForSample+p->Clock);
p->ToneFreqPos[i]=-p->ToneFreqPos[i]; /* Flip the flip-flop */
} else {
p->ToneFreqPos[i]=1; /* stuck value */
p->IntermediatePos[i]=FLT_MIN;
}
p->ToneFreqVals[i]+=p->Registers[i*2]*(p->NumClocksForSample/p->Registers[i*2]+1);
} else p->IntermediatePos[i]=FLT_MIN;
}
/* Noise channel */
if (p->ToneFreqVals[3]<=0) { /* If it gets below 0... */
p->ToneFreqPos[3]=-p->ToneFreqPos[3]; /* Flip the flip-flop */
if (p->NoiseFreq!=0x80) /* If not matching tone2, decrement counter */
p->ToneFreqVals[3]+=p->NoiseFreq*(p->NumClocksForSample/p->NoiseFreq+1);
if (p->ToneFreqPos[3]==1) { /* Only once per cycle... */
int Feedback;
if (p->Registers[6]&0x4) { /* White noise */
/* Calculate parity of fed-back bits for feedback */
switch (p->WhiteNoiseFeedback) {
/* Do some optimised calculations for common (known) feedback values */
case 0x0003: /* SC-3000, BBC %00000011 */
case 0x0009: /* SMS, GG, MD %00001001 */
/* If two bits fed back, I can do Feedback=(nsr & fb) && (nsr & fb ^ fb) */
/* since that's (one or more bits set) && (not all bits set) */
Feedback=((p->NoiseShiftRegister&p->WhiteNoiseFeedback) && ((p->NoiseShiftRegister&p->WhiteNoiseFeedback)^p->WhiteNoiseFeedback));
break;
default: /* Default handler for all other feedback values */
Feedback=p->NoiseShiftRegister&p->WhiteNoiseFeedback;
Feedback^=Feedback>>8;
Feedback^=Feedback>>4;
Feedback^=Feedback>>2;
Feedback^=Feedback>>1;
Feedback&=1;
break;
}
} else /* Periodic noise */
Feedback=p->NoiseShiftRegister&1;
p->NoiseShiftRegister=(p->NoiseShiftRegister>>1) | (Feedback << (p->SRWidth-1));
/* Original code: */
/* p->NoiseShiftRegister=(p->NoiseShiftRegister>>1) | ((p->Registers[6]&0x4?((p->NoiseShiftRegister&0x9) && (p->NoiseShiftRegister&0x9^0x9)):p->NoiseShiftRegister&1)<<15); */
}
}
}
}
/*void SN76489_UpdateOne(int which, int *l, int *r)
{
INT16 tl,tr;
INT16 *buff[2]={&tl,&tr};
SN76489_Update(which,buff,1);
*l=tl;
*r=tr;
}*/
int SN76489_GetMute()
{
return SN76489.Mute;
}
void SN76489_SetMute(int val)
{
SN76489.Mute=val;
}
int SN76489_GetVolType()
{
return SN76489.VolumeArray;
}
void SN76489_SetVolType(int val)
{
SN76489.VolumeArray=val;
}
void SN76489_SetPanning(int ch0, int ch1, int ch2, int ch3)
{
SN76489.panning[0]=ch0;
SN76489.panning[1]=ch1;
SN76489.panning[2]=ch2;
SN76489.panning[3]=ch3;
}

27
source/sound/sn76489.h
View File

@ -37,32 +37,6 @@
#ifndef _SN76489_H_ #ifndef _SN76489_H_
#define _SN76489_H_ #define _SN76489_H_
/* SN76489 clone in Sega's VDP chips (315-5124, 315-5246, 315-5313, Game Gear) */
#define FB_SEGAVDP 0x0009
#define SRW_SEGAVDP 16
typedef struct
{
/* Configuration */
int BoostNoise; // double noise volume when non-zero
/* PSG registers: */
int Registers[8]; /* Tone, vol x4 */
int LatchedRegister;
int NoiseShiftRegister;
int NoiseFreq; /* Noise channel signal generator frequency */
/* Output calculation variables */
int ToneFreqVals[4]; /* Frequency register values (counters) */
int ToneFreqPos[4]; /* Frequency channel flip-flops */
int Channels[4]; /* Value of each channel, before stereo is applied */
/* Blip-Buffer variables */
struct blip_buffer_t* blip_buffer; /* delta resampler */
int chan_amp[4]; /* current channel amplitudes in delta buffers */
} SN76489_Context;
/* Function prototypes */ /* Function prototypes */
extern void SN76489_Init(int PSGClockValue, int SamplingRate); extern void SN76489_Init(int PSGClockValue, int SamplingRate);
extern void SN76489_Reset(void); extern void SN76489_Reset(void);
@ -74,6 +48,7 @@ extern int SN76489_GetContextSize(void);
extern void SN76489_Write(int data); extern void SN76489_Write(int data);
extern void SN76489_Update(INT16 *buffer, int length); extern void SN76489_Update(INT16 *buffer, int length);
extern void SN76489_BoostNoise(int boost); extern void SN76489_BoostNoise(int boost);
extern void SN76489_Config(int mute, int volume, int feedback, int sr_width, int boost_noise);
#endif /* _SN76489_H_ */ #endif /* _SN76489_H_ */

2
source/state.h
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@ -24,7 +24,7 @@
#define _STATE_H_ #define _STATE_H_
#define STATE_SIZE 0x28000 #define STATE_SIZE 0x28000
#define STATE_VERSION "GENPLUS-GX 1.3.2" #define STATE_VERSION "GENPLUS-GX 1.4.0"
/* Function prototypes */ /* Function prototypes */
extern int state_load(unsigned char *buffer); extern int state_load(unsigned char *buffer);

2
source/system.c
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@ -86,7 +86,7 @@ void audio_update (int size)
for (i = 0; i < size; i ++) for (i = 0; i < size; i ++)
{ {
/* PSG samples (mono) */ /* PSG samples (mono) */
l = r = (((int)*psg++) * psg_preamp)/100; l = r = ((*psg++) * psg_preamp)/100;
/* FM samples (stereo) */ /* FM samples (stereo) */
l += (*fm[0]++ * fm_preamp)/100; l += (*fm[0]++ * fm_preamp)/100;