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https://github.com/ekeeke/Genesis-Plus-GX.git
synced 2024-09-10 16:53:15 +02:00
.fixed broken PSG noise frequency
.improved accuracy Game Gear PSG stereo (cycle-accurate)
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c830a70872
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54687cde58
@ -547,7 +547,7 @@ void io_gg_write(unsigned int offset, unsigned int data)
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case 6: /* PSG Stereo output control */
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io_reg[6] = data;
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SN76489_Config(config.psg_preamp, config.psgBoostNoise, data);
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SN76489_Config(Z80.cycles, config.psg_preamp, config.psgBoostNoise, data);
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return;
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default: /* Read-only */
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@ -157,29 +157,6 @@ void SN76489_Reset()
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SN76489.clocks = 0;
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}
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void SN76489_Config(int preAmp, int boostNoise, int stereo)
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{
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int i;
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for (i=0; i<4; i++)
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{
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/* stereo channel pre-amplification */
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SN76489.PreAmp[i][0] = preAmp * ((stereo >> (i*2)) & 1);
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SN76489.PreAmp[i][1] = preAmp * ((stereo >> (i*2 + 1)) & 1);
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/* noise channel boost */
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if (i == 3)
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{
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SN76489.PreAmp[3][0] = SN76489.PreAmp[3][0] << boostNoise;
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SN76489.PreAmp[3][1] = SN76489.PreAmp[3][1] << boostNoise;
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}
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/* update stereo channel amplitude */
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SN76489.Channel[i][0]= (PSGVolumeValues[SN76489.Registers[i*2 + 1]] * SN76489.PreAmp[i][0]) / 100;
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SN76489.Channel[i][1]= (PSGVolumeValues[SN76489.Registers[i*2 + 1]] * SN76489.PreAmp[i][1]) / 100;
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}
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}
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void *SN76489_GetContextPtr(void)
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{
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return (uint8 *)&SN76489;
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@ -331,6 +308,39 @@ static void SN76489_RunUntil(unsigned int clocks)
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}
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}
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void SN76489_Config(unsigned int clocks, int preAmp, int boostNoise, int stereo)
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{
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int i;
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/* cycle-accurate Game Gear stereo */
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if (clocks > SN76489.clocks)
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{
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/* Run chip until current timestamp */
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SN76489_RunUntil(clocks);
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/* Update internal M-cycle counter */
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SN76489.clocks += ((clocks - SN76489.clocks + PSG_MCYCLES_RATIO - 1) / PSG_MCYCLES_RATIO) * PSG_MCYCLES_RATIO;
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}
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for (i=0; i<4; i++)
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{
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/* stereo channel pre-amplification */
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SN76489.PreAmp[i][0] = preAmp * ((stereo >> (i*2)) & 1);
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SN76489.PreAmp[i][1] = preAmp * ((stereo >> (i*2 + 1)) & 1);
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/* noise channel boost */
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if (i == 3)
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{
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SN76489.PreAmp[3][0] = SN76489.PreAmp[3][0] << boostNoise;
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SN76489.PreAmp[3][1] = SN76489.PreAmp[3][1] << boostNoise;
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}
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/* update stereo channel amplitude */
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SN76489.Channel[i][0]= (PSGVolumeValues[SN76489.Registers[i*2 + 1]] * SN76489.PreAmp[i][0]) / 100;
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SN76489.Channel[i][1]= (PSGVolumeValues[SN76489.Registers[i*2 + 1]] * SN76489.PreAmp[i][1]) / 100;
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}
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}
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void SN76489_Update(unsigned int clocks)
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{
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int i;
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@ -424,7 +434,7 @@ void SN76489_Write(unsigned int clocks, unsigned int data)
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SN76489.NoiseShiftRegister = NoiseInitialState;
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/* set noise signal generator frequency */
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SN76489.NoiseFreq = (0x10 << (data&0x3)) * PSG_MCYCLES_RATIO;
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SN76489.NoiseFreq = 0x10 << (data&0x3);
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break;
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}
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@ -14,7 +14,7 @@
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/* Function prototypes */
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extern void SN76489_Init(blip_t* left, blip_t* right, int type);
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extern void SN76489_Reset(void);
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extern void SN76489_Config(int preAmp, int boostNoise, int stereo);
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extern void SN76489_Config(unsigned int clocks, int preAmp, int boostNoise, int stereo);
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extern void SN76489_Write(unsigned int clocks, unsigned int data);
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extern void SN76489_Update(unsigned int cycles);
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extern void *SN76489_GetContextPtr(void);
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@ -102,7 +102,7 @@ void sound_init( void )
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}
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/* Initialize PSG chip */
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SN76489_Config(config.psg_preamp, config.psgBoostNoise, 0xff);
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SN76489_Config(0, config.psg_preamp, config.psgBoostNoise, 0xff);
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}
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void sound_reset(void)
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@ -117,12 +117,12 @@ int state_load(unsigned char *state)
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if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
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{
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SN76489_Init(snd.blips[0][0], snd.blips[0][1], SN_INTEGRATED);
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SN76489_Config(config.psg_preamp, config.psgBoostNoise, 0xff);
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SN76489_Config(0, config.psg_preamp, config.psgBoostNoise, 0xff);
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}
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else
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{
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SN76489_Init(snd.blips[0][0], snd.blips[0][1], (system_hw < SYSTEM_MARKIII) ? SN_DISCRETE : SN_INTEGRATED);
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SN76489_Config(config.psg_preamp, config.psgBoostNoise, io_reg[6]);
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SN76489_Config(0, config.psg_preamp, config.psgBoostNoise, io_reg[6]);
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}
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/* 68000 */
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