frodo-wii/Src/SID_SDL.h

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/*
* SID_SDL.h - 6581 emulation, SDL specific stuff
*
* Frodo (C) 1994-1997,2002-2005 Christian Bauer
*
* SDL stuff by Simon Kagstrom
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <unistd.h>
#include <fcntl.h>
#include <SDL.h>
#include "VIC.h"
static SDL_AudioSpec spec;
#define FRODO_SNDBUF 512
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#define SOUNDBUFSIZE 1536
#define N_BUFS 8
static int16 soundbuffer[N_BUFS][FRODO_SNDBUF];
static int head, tail;
static void fill_audio(void *udata, Uint8 *stream, int len)
{
const int sz = FRODO_SNDBUF * 2;
int off = 0;
memset(stream, 0, len);
while (tail != head)
{
//printf("Copying %d bytes at off %d, tail %d, head %d\n", len, off, tail, head);
memcpy(stream + off, soundbuffer[tail], sz);
off += sz;
if (off >= len)
break;
tail = (tail + 1) % N_BUFS;
}
}
/*
* Initialization
*/
void DigitalRenderer::init_sound(void)
{
this->sndbufsize = FRODO_SNDBUF;
/* Set the audio format */
spec.freq = 32000;
spec.format = AUDIO_S16SYS;
spec.channels = 1; /* 1 = mono, 2 = stereo */
spec.samples = SOUNDBUFSIZE;
spec.callback = fill_audio;
spec.userdata = (void*)this;
ready = false;
if ( SDL_OpenAudio(&spec, NULL) < 0 ) {
fprintf(stderr, "Couldn't open audio: %s\n", SDL_GetError());
return ;
}
this->sound_buffer = new int16[this->sndbufsize];
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memset(this->sound_buffer, 0, sizeof(int16) * this->sndbufsize);
ready = true;
SDL_PauseAudio(0);
}
/*
* Destructor
*/
DigitalRenderer::~DigitalRenderer()
{
SDL_CloseAudio();
}
/*
* Pause sound output
*/
void DigitalRenderer::Pause(void)
{
SDL_PauseAudio(1);
}
/*
* Resume sound output
*/
void DigitalRenderer::Resume(void)
{
SDL_PauseAudio(0);
}
/*
* Fill buffer, sample volume (for sampled voice)
*/
void DigitalRenderer::PushVolume(uint8 vol)
{
static int divisor = 0;
static int to_output = 0;
sample_buf[sample_in_ptr] = volume;
sample_in_ptr = (sample_in_ptr + 1) % SAMPLE_BUF_SIZE;
/*
* Now see how many samples have to be added for this line
*/
divisor += SAMPLE_FREQ;
while (divisor >= 0)
{
divisor -= TOTAL_RASTERS*SCREEN_FREQ;
to_output++;
}
if (to_output >= sndbufsize) {
int datalen = sndbufsize;
to_output -= datalen;
SDL_LockAudio();
calc_buffer(soundbuffer[head], datalen * 2);
head = (head + 1) % N_BUFS;
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if (head == tail) {
tail = (head + 1) % N_BUFS;
}
SDL_UnlockAudio();
}
}
void DigitalRenderer::EmulateLine(void)
{
if (!ready)
return;
this->PushVolume(volume);
}