Mercurial > repos > blastem
view psg.c @ 1863:d60f2d7c02a5
Differentiate between the full Sega mapper and the SRAM only one. Fixes crash on save state load for Phantasy Star IV and other games that use the same mapper
author | Michael Pavone <pavone@retrodev.com> |
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date | Tue, 14 May 2019 23:20:35 -0700 |
parents | 6ce36c3f250b |
children | 4c322abd9fa5 |
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/* Copyright 2013 Michael Pavone This file is part of BlastEm. BlastEm is free software distributed under the terms of the GNU General Public License version 3 or greater. See COPYING for full license text. */ #include "psg.h" #include "render.h" #include "blastem.h" #include <string.h> #include <stdlib.h> #include <stdio.h> #include <math.h> void psg_init(psg_context * context, uint32_t master_clock, uint32_t clock_div) { memset(context, 0, sizeof(*context)); context->audio = render_audio_source(master_clock, clock_div, 1); context->clock_inc = clock_div; for (int i = 0; i < 4; i++) { context->volume[i] = 0xF; } } void psg_free(psg_context *context) { render_free_source(context->audio); free(context); } void psg_adjust_master_clock(psg_context * context, uint32_t master_clock) { render_audio_adjust_clock(context->audio, master_clock, context->clock_inc); } void psg_write(psg_context * context, uint8_t value) { if (value & 0x80) { context->latch = value & 0x70; uint8_t channel = value >> 5 & 0x3; if (value & 0x10) { context->volume[channel] = value & 0xF; } else { if (channel == 3) { switch(value & 0x3) { case 0: case 1: case 2: context->counter_load[3] = 0x10 << (value & 0x3); context->noise_use_tone = 0; break; default: context->counter_load[3] = context->counter_load[2]; context->noise_use_tone = 1; } context->noise_type = value & 0x4; context->lsfr = 0x8000; } else { context->counter_load[channel] = (context->counter_load[channel] & 0x3F0) | (value & 0xF); if (channel == 2 && context->noise_use_tone) { context->counter_load[3] = context->counter_load[2]; } } } } else { if (!(context->latch & 0x10)) { uint8_t channel = context->latch >> 5 & 0x3; if (channel != 3) { context->counter_load[channel] = (value << 4 & 0x3F0) | (context->counter_load[channel] & 0xF); if (channel == 2 && context->noise_use_tone) { context->counter_load[3] = context->counter_load[2]; } } } } } #define PSG_VOL_DIV 14 //table shamelessly swiped from PSG doc from smspower.org static int16_t volume_table[16] = { 32767/PSG_VOL_DIV, 26028/PSG_VOL_DIV, 20675/PSG_VOL_DIV, 16422/PSG_VOL_DIV, 13045/PSG_VOL_DIV, 10362/PSG_VOL_DIV, 8231/PSG_VOL_DIV, 6568/PSG_VOL_DIV, 5193/PSG_VOL_DIV, 4125/PSG_VOL_DIV, 3277/PSG_VOL_DIV, 2603/PSG_VOL_DIV, 2067/PSG_VOL_DIV, 1642/PSG_VOL_DIV, 1304/PSG_VOL_DIV, 0 }; void psg_run(psg_context * context, uint32_t cycles) { while (context->cycles < cycles) { for (int i = 0; i < 4; i++) { if (context->counters[i]) { context->counters[i] -= 1; } if (!context->counters[i]) { context->counters[i] = context->counter_load[i]; context->output_state[i] = !context->output_state[i]; if (i == 3 && context->output_state[i]) { context->noise_out = context->lsfr & 1; context->lsfr = (context->lsfr >> 1) | (context->lsfr << 15); if (context->noise_type) { //white noise if (context->lsfr & 0x40) { context->lsfr ^= 0x8000; } } } } } int16_t accum = 0; for (int i = 0; i < 3; i++) { if (context->output_state[i]) { accum += volume_table[context->volume[i]]; } } if (context->noise_out) { accum += volume_table[context->volume[3]]; } render_put_mono_sample(context->audio, accum); context->cycles += context->clock_inc; } } void psg_serialize(psg_context *context, serialize_buffer *buf) { save_int16(buf, context->lsfr); save_buffer16(buf, context->counter_load, 4); save_buffer16(buf, context->counters, 4); save_buffer8(buf, context->volume, 4); uint8_t output_state = context->output_state[0] << 3 | context->output_state[1] << 2 | context->output_state[2] << 1 | context->output_state[3] | context->noise_use_tone << 4; save_int8(buf, output_state); save_int8(buf, context->noise_type); save_int8(buf, context->latch); save_int32(buf, context->cycles); } void psg_deserialize(deserialize_buffer *buf, void *vcontext) { psg_context *context = vcontext; context->lsfr = load_int16(buf); load_buffer16(buf, context->counter_load, 4); load_buffer16(buf, context->counters, 4); load_buffer8(buf, context->volume, 4); uint8_t output_state = load_int8(buf); context->output_state[0] = output_state >> 3 & 1; context->output_state[1] = output_state >> 2 & 1; context->output_state[2] = output_state >> 1 & 1; context->output_state[3] = output_state & 1; context->noise_use_tone = output_state >> 4 & 1; context->noise_type = load_int8(buf); context->latch = load_int8(buf); context->cycles = load_int32(buf); }