Mercurial > repos > blastem
view psg.c @ 915:9e882eca717e
Initial support for relative mouse mode and skeleton of support for capture mode. Avoid mouse position overflow in absolute mode. Allow absolute mode to be set by ROM DB.
author | Michael Pavone <pavone@retrodev.com> |
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date | Tue, 15 Dec 2015 20:01:50 -0800 |
parents | 252dfd29831d |
children | bd549b25c362 |
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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> void psg_init(psg_context * context, uint32_t sample_rate, uint32_t master_clock, uint32_t clock_div, uint32_t samples_frame) { memset(context, 0, sizeof(*context)); context->audio_buffer = malloc(sizeof(*context->audio_buffer) * samples_frame); context->back_buffer = malloc(sizeof(*context->audio_buffer) * samples_frame); context->clock_inc = clock_div; context->sample_rate = sample_rate; context->samples_frame = samples_frame; psg_adjust_master_clock(context, master_clock); for (int i = 0; i < 4; i++) { context->volume[i] = 0xF; } } void psg_free(psg_context *context) { free(context->audio_buffer); //TODO: Figure out how to make this 100% safe //audio thread could still be using this free(context->back_buffer); free(context); } #define BUFFER_INC_RES 1000000000UL void psg_adjust_master_clock(psg_context * context, uint32_t master_clock) { uint64_t old_inc = context->buffer_inc; context->buffer_inc = ((BUFFER_INC_RES * (uint64_t)context->sample_rate) / (uint64_t)master_clock) * (uint64_t)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 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; } } } } } for (int i = 0; i < 3; i++) { if (context->output_state[i]) { context->accum += volume_table[context->volume[i]]; } } if (context->noise_out) { context->accum += volume_table[context->volume[3]]; } context->sample_count++; context->buffer_fraction += context->buffer_inc; if (context->buffer_fraction >= BUFFER_INC_RES) { context->buffer_fraction -= BUFFER_INC_RES; context->audio_buffer[context->buffer_pos++] = context->accum / context->sample_count; context->accum = context->sample_count = 0; if (context->buffer_pos == context->samples_frame) { if (!headless) { render_wait_psg(context); } } } context->cycles += context->clock_inc; } }