380 lines
11 KiB
C++
380 lines
11 KiB
C++
/*
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* Copyright (C) 2010-2019 Fabio Cavallo (aka FHorse)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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// additional modifications by tildearrow for furnace
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#include <string.h>
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#include "apu.h"
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void apu_tick(struct NESAPU* a, int len) {
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if (len<=a->timestamp) return;
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int rem=len-a->timestamp;
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if (rem>1) {
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// output now just in case
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int sample=(pulse_output(a)+tnd_output(a))<<6;
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if (sample!=a->lastSample) {
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blip_add_delta(a->bb,a->timestamp,sample-a->lastSample);
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a->lastSample=sample;
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}
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}
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while (rem>0) {
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// predict advance
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int advance=rem;
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if (a->r4017.jitter.delay) {
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advance=1;
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}
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if (advance>a->apu.cycles) {
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advance=a->apu.cycles;
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}
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if (advance>a->S1.frequency) {
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advance=a->S1.frequency;
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}
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if (advance>a->S2.frequency) {
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advance=a->S2.frequency;
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}
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if (advance>a->TR.frequency) {
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advance=a->TR.frequency;
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}
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if (advance>a->NS.frequency) {
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advance=a->NS.frequency;
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}
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if (advance>a->DMC.frequency) {
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advance=a->DMC.frequency;
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}
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if (advance<1) advance=1;
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/* sottraggo il numero di cicli eseguiti */
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a->apu.cycles-=advance;
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/*
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* questo flag sara' a TRUE solo nel ciclo
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* in cui viene eseguito il length counter.
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*/
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a->apu.length_clocked = FALSE;
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/*
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* se e' settato il delay del $4017, essendo
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* questo il ciclo successivo, valorizzo il
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* registro.
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*/
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#if defined (VECCHIA_GESTIONE_JITTER)
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if (r4017.jitter.delay) {
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r4017.jitter.delay = FALSE;
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r4017_jitter();
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}
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#else
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if (a->r4017.jitter.delay) {
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a->r4017.jitter.delay = FALSE;
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r4017_jitter(0)
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}
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r4017_reset_frame()
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#endif
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/* quando apu.cycles e' a 0 devo eseguire uno step */
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if (!a->apu.cycles) {
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switch (a->apu.step) {
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case 0:
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/*
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* nel mode 1 devo eseguire il
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* length counter e lo sweep.
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*/
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if (a->apu.mode == APU_48HZ) {
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length_clock()
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sweep_clock()
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}
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envelope_clock()
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/* triangle's linear counter */
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linear_clock()
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/* passo al prossimo step */
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apu_change_step(++a->apu.step);
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break;
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case 1:
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/* nel mode 0 devo eseguire il length counter */
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if (a->apu.mode == APU_60HZ) {
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length_clock()
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sweep_clock()
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}
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envelope_clock()
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/* triangle's linear counter */
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linear_clock()
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/* passo al prossimo step */
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apu_change_step(++a->apu.step);
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break;
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case 2:
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/*
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* nel mode 1 devo eseguire il
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* length counter e lo sweep.
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*/
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if (a->apu.mode == APU_48HZ) {
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length_clock()
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sweep_clock()
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}
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envelope_clock()
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/* triangle's linear counter */
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linear_clock()
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/* passo al prossimo step */
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apu_change_step(++a->apu.step);
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break;
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case 3:
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/*
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* gli step 3, 4 e 5 settano il bit 6 del $4015
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* ma solo nel 4 genero un IRQ.
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*/
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if (a->apu.mode == APU_60HZ) {
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/*
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* se e' a 0 il bit 6 del $4017 (interrupt
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* inhibit flag) allora devo generare un IRQ.
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*/
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if (!(a->r4017.value & 0x40)) {
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/* setto il bit 6 del $4015 */
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a->r4015.value |= 0x40;
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}
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} else {
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/* nel mode 1 devo eseguire l'envelope */
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envelope_clock()
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/* triangle's linear counter */
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linear_clock()
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}
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/* passo al prossimo step */
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apu_change_step(++a->apu.step);
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break;
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case 4:
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/*
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* gli step 3, 4 e 5 settano il bit 6 del $4015
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* ma solo nel 4 genero un IRQ.
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*/
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if (a->apu.mode == APU_60HZ) {
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length_clock()
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sweep_clock()
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envelope_clock()
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/* triangle's linear counter */
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linear_clock()
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/*
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* se e' a 0 il bit 6 del $4017 (interrupt
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* inhibit flag) allora devo generare un IRQ.
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*/
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if (!(a->r4017.value & 0x40)) {
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/* setto il bit 6 del $4015 */
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a->r4015.value |= 0x40;
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}
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}
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/* passo al prossimo step */
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apu_change_step(++a->apu.step);
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break;
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case 5:
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/*
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* gli step 3, 4 e 5 settano il bit 6 del $4015
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* ma solo nel 4 genero un IRQ.
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*/
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if (a->apu.mode == APU_60HZ) {
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/*
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* se e' a 0 il bit 6 del $4017 (interrupt
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* inhibit flag) allora devo generare un IRQ.
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*/
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if (!(a->r4017.value & 0x40)) {
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/* setto il bit 6 del $4015 */
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a->r4015.value |= 0x40;
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}
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a->apu.step++;
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} else {
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/* nel mode 1 devo ricominciare il ciclo */
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a->apu.step = 0;
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}
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/* passo al prossimo step */
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apu_change_step(a->apu.step);
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break;
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case 6:
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/* da qui ci passo solo nel mode 0 */
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envelope_clock()
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/* triangle's linear counter */
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linear_clock()
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/* questo e' il passaggio finale del mode 0 */
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a->apu.step = 1;
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/* passo al prossimo step */
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apu_change_step(a->apu.step);
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break;
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}
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}
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/*
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* eseguo un ticket per ogni canale
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* valorizzandone l'output.
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*/
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// SQUARE 1 TICK
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if (!(a->S1.frequency-=advance)) {
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square_output(a->S1, 0)
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a->S1.frequency = (a->S1.timer + 1) << 1;
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a->S1.sequencer = (a->S1.sequencer + 1) & 0x07;
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}
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// SQUARE 2 TICK
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if (!(a->S2.frequency-=advance)) {
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square_output(a->S2, 0)
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a->S2.frequency = (a->S2.timer + 1) << 1;
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a->S2.sequencer = (a->S2.sequencer + 1) & 0x07;
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}
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// TRIANGLE TICK
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if (!(a->TR.frequency-=advance)) {
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a->TR.frequency = a->TR.timer + 1;
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if (a->TR.length.value && a->TR.linear.value) {
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a->TR.sequencer = (a->TR.sequencer + 1) & 0x1F;
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triangle_output()
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}
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}
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// NOISE TICK
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if (!(a->NS.frequency-=advance)) {
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if (a->NS.mode) {
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a->NS.shift = (a->NS.shift >> 1) | (((a->NS.shift ^ (a->NS.shift >> 6)) & 0x0001) << 14);
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} else {
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a->NS.shift = (a->NS.shift >> 1) | (((a->NS.shift ^ (a->NS.shift >> 1)) & 0x0001) << 14);
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}
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a->NS.shift &= 0x7FFF;
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noise_output()
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a->NS.frequency = noise_timer[a->apu.type][a->NS.timer];
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}
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// DMC TICK
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if (!(a->DMC.frequency-=advance)) {
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if (!a->DMC.silence) {
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if (!(a->DMC.shift & 0x01)) {
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if (a->DMC.counter > 1) {
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a->DMC.counter -= 2;
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}
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} else {
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if (a->DMC.counter < 126) {
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a->DMC.counter += 2;
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}
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}
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}
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a->DMC.shift >>= 1;
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dmc_output();
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if (!(--a->DMC.counter_out)) {
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a->DMC.counter_out = 8;
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if (!a->DMC.empty) {
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a->DMC.shift = a->DMC.buffer;
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a->DMC.empty = TRUE;
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a->DMC.silence = FALSE;
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} else {
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a->DMC.silence = TRUE;
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}
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}
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a->DMC.frequency = dmc_rate[a->apu.type][a->DMC.rate_index];
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}
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if (a->DMC.empty && a->DMC.remain) {
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BYTE tick = 4;
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switch (a->DMC.tick_type) {
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case DMC_CPU_WRITE:
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tick = 3;
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break;
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case DMC_R4014:
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tick = 2;
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break;
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case DMC_NNL_DMA:
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tick = 1;
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break;
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}
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{
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a->DMC.buffer = a->readDMC(a->readDMCUser,a->DMC.address);
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}
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/* e naturalmente incremento anche quelli eseguiti dall'opcode */
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a->apu.cpu_cycles += tick;
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/* salvo a che ciclo dell'istruzione avviene il dma */
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a->DMC.dma_cycle = a->apu.cpu_opcode_cycle;
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/* il DMC non e' vuoto */
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a->DMC.empty = FALSE;
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if (++a->DMC.address > 0xFFFF) {
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a->DMC.address = 0x8000;
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}
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if (!(--a->DMC.remain)) {
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if (a->DMC.loop) {
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a->DMC.remain = a->DMC.length;
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a->DMC.address = a->DMC.address_start;
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} else if (a->DMC.irq_enabled) {
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a->r4015.value |= 0x80;
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}
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}
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}
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a->r4011.cycles+=advance;
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if (advance&1) {
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a->apu.odd_cycle=!a->apu.odd_cycle;
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}
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// output sample
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a->timestamp+=advance-1;
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int sample=(pulse_output(a)+tnd_output(a))<<6;
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if (sample!=a->lastSample) {
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blip_add_delta(a->bb,a->timestamp,sample-a->lastSample);
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a->lastSample=sample;
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}
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rem-=advance;
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a->timestamp++;
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}
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a->timestamp=len;
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}
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void apu_turn_on(struct NESAPU* a, BYTE apu_type) {
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memset(&a->apu, 0x00, sizeof(a->apu));
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memset(&a->r4015, 0x00, sizeof(a->r4015));
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memset(&a->r4017, 0x00, sizeof(a->r4017));
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/* azzero tutte le variabili interne dei canali */
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memset(&a->S1, 0x00, sizeof(a->S1));
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memset(&a->S2, 0x00, sizeof(a->S2));
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memset(&a->TR, 0x00, sizeof(a->TR));
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memset(&a->NS, 0x00, sizeof(a->NS));
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memset(&a->DMC, 0x00, sizeof(a->DMC));
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/* al reset e' sempre settato a 60Hz */
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a->apu.mode = APU_60HZ;
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/* per favore non fatemi questo... e' terribile */
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a->apu.type = apu_type;
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apu_change_step(a->apu.step);
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/* valori iniziali dei vari canali */
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a->S1.frequency = 1;
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a->S1.sweep.delay = 1;
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a->S1.sweep.divider = 1;
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a->S2.frequency = 1;
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a->S2.sweep.delay = 1;
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a->S2.sweep.divider = 1;
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a->TR.frequency = 1;
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/* questo era 0 ma produce click nell'audio */
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a->TR.sequencer = 7;
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a->NS.frequency = 1;
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a->NS.shift = 1;
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a->DMC.frequency = 1;
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a->DMC.empty = TRUE;
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a->DMC.silence = TRUE;
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a->DMC.counter_out = 8;
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// sembra che l'address del DMC al power on dia valorizzato a 0xC000
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// e la lunghezza del sample sia settato a 1 byte.
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// http://forums.nesdev.com/viewtopic.php?f=3&t=18278
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a->DMC.length = 1;
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a->DMC.address_start = 0xC000;
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a->apu.odd_cycle = 0;
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// come non viene inizializzato? Vorrei qualche spiegazione...
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a->r4011.frames = 0;
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a->lastSample = 0;
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a->S1.timer=2048;
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a->S2.timer=2048;
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a->TR.timer=2048;
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a->NS.timer=0x0FE4;
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}
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