ad8437e5ae
in one editor it's 8 spaces, in another it's 2... spaces on the other hand are the same regardless of editor
139 lines
3.8 KiB
C
139 lines
3.8 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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#include <stdio.h>
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#include <string.h>
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#include "fds.h"
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enum { TRANSFERED_8BIT = 0x02, END_OF_HEAD = 0x40 };
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static const BYTE volume_wave[4] = { 39, 26, 19, 15 };
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void fds_reset(struct _fds* fds) {
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memset(fds,0,sizeof(struct _fds));
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}
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void extcl_apu_tick_FDS(struct _fds* fds) {
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SWORD freq;
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/* volume unit */
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if (fds->snd.volume.mode) {
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fds->snd.volume.gain = fds->snd.volume.speed;
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} else if (!fds->snd.envelope.disabled && fds->snd.envelope.speed) {
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if (fds->snd.volume.counter) {
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fds->snd.volume.counter--;
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} else {
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fds->snd.volume.counter = (fds->snd.envelope.speed << 3) * (fds->snd.volume.speed + 1);
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if (fds->snd.volume.increase) {
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if (fds->snd.volume.gain < 32) {
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fds->snd.volume.gain++;
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}
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} else if (fds->snd.volume.gain) {
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fds->snd.volume.gain--;
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}
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}
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}
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/* sweep unit */
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if (fds->snd.sweep.mode) {
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fds->snd.sweep.gain = fds->snd.sweep.speed;
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} else if (!fds->snd.envelope.disabled && fds->snd.envelope.speed) {
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if (fds->snd.sweep.counter) {
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fds->snd.sweep.counter--;
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} else {
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fds->snd.sweep.counter = (fds->snd.envelope.speed << 3) * (fds->snd.sweep.speed + 1);
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if (fds->snd.sweep.increase) {
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if (fds->snd.sweep.gain < 32) {
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fds->snd.sweep.gain++;
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}
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} else if (fds->snd.sweep.gain) {
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fds->snd.sweep.gain--;
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}
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}
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}
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/* modulation unit */
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freq = fds->snd.main.frequency;
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if (!fds->snd.modulation.disabled && fds->snd.modulation.frequency) {
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if ((fds->snd.modulation.counter -= fds->snd.modulation.frequency) < 0) {
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SWORD temp, temp2, a, d;
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SBYTE adj = fds->snd.modulation.data[fds->snd.modulation.index];
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fds->snd.modulation.counter += 65536;
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if (++fds->snd.modulation.index == 64) {
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fds->snd.modulation.index = 0;
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}
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if (adj == -4) {
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fds->snd.sweep.bias = 0;
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} else {
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fds->snd.sweep.bias += adj;
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}
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temp = fds->snd.sweep.bias * ((fds->snd.sweep.gain < 32) ? fds->snd.sweep.gain : 32);
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a = 64;
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d = 0;
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if (temp <= 0) {
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d = 15;
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} else if (temp < 3040) { //95 * 32
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a = 66;
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d = -31;
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}
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temp2 = a + (SBYTE) ((temp - d) / 16 - a);
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fds->snd.modulation.mod = freq * temp2 / 64;
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}
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if (freq) {
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freq += fds->snd.modulation.mod;
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}
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}
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/* main unit */
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if (fds->snd.main.silence) {
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fds->snd.main.output = 0;
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return;
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}
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if (freq && !fds->snd.wave.writable) {
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if ((fds->snd.wave.counter -= freq) < 0) {
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WORD level;
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fds->snd.wave.counter += 65536;
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level = (fds->snd.volume.gain < 32 ? fds->snd.volume.gain : 32)
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* volume_wave[fds->snd.wave.volume];
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/* valore massimo dell'output (63 * (39 * 32)) = 78624 */
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/*fds->snd.main.output = (fds->snd.wave.data[fds->snd.wave.index] * level) >> 4;*/
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fds->snd.main.output = (fds->snd.wave.data[fds->snd.wave.index] * level) >> 3;
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if (++fds->snd.wave.index == 64) {
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fds->snd.wave.index = 0;
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}
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fds->snd.wave.clocked = TRUE;
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}
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}
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}
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