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Added square wave audio, no ASDR support yet.

This commit is contained in:
Andrew Alderwick 2021-04-02 16:05:08 +01:00
parent 1216b58cc1
commit 09091275b5
1 changed files with 69 additions and 5 deletions
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74
src/emulator.c
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@ -49,11 +49,35 @@ Uint8 font[][8] = {
{0x00, 0x7e, 0x40, 0x7c, 0x40, 0x40, 0x7e, 0x00},
{0x00, 0x7e, 0x40, 0x40, 0x7c, 0x40, 0x40, 0x00}};
#define SAMPLE_FREQUENCY 48000
static Uint32 note_periods[12] = { /* middle C (C4) is note 60 */
(Uint32) 0xfa7e * SAMPLE_FREQUENCY, /* C-1 */
(Uint32) 0xec6f * SAMPLE_FREQUENCY,
(Uint32) 0xdf2a * SAMPLE_FREQUENCY, /* D-1 */
(Uint32) 0xd2a4 * SAMPLE_FREQUENCY,
(Uint32) 0xc6d1 * SAMPLE_FREQUENCY, /* E-1 */
(Uint32) 0xbba8 * SAMPLE_FREQUENCY, /* F-1 */
(Uint32) 0xb120 * SAMPLE_FREQUENCY,
(Uint32) 0xa72f * SAMPLE_FREQUENCY, /* G-1 */
(Uint32) 0x9dcd * SAMPLE_FREQUENCY,
(Uint32) 0x94f2 * SAMPLE_FREQUENCY, /* A-1 */
(Uint32) 0x8c95 * SAMPLE_FREQUENCY,
(Uint32) 0x84b2 * SAMPLE_FREQUENCY /* B-1 */
};
static struct audio_channel {
Uint32 period, count;
int value;
Sint16 volume;
} channels[4];
static SDL_Window *gWindow;
static SDL_Renderer *gRenderer;
static SDL_Texture *gTexture;
static SDL_AudioDeviceID audio_id;
static Screen screen;
static Device *devscreen, *devmouse, *devkey, *devctrl;
static Device *devscreen, *devmouse, *devkey, *devctrl, *devaudio;
#pragma mark - Helpers
@ -212,6 +236,28 @@ togglezoom(Uxn *u)
redraw(pixels, u);
}
void
audio_callback(void* userdata, Uint8* stream, int len) {
Sint16 *samples = (Sint16 *) stream;
int i, j;
len >>= 1; /* use len for number of samples, not bytes */
for (j = 0; j < len; ++j) samples[j] = 0;
for (i = 0; i < 4; ++i) {
struct audio_channel *c = &channels[i];
if (!c->volume) continue;
if (c->period < (1 << 20)) continue;
for (j = 0; j < len; ++j) {
c->count += 1 << 20;
while (c->count > c->period) {
c->value = !c->value;
c->count -= c->period;
}
samples[j] += (c->value * 2 - 1) * c->volume;
}
}
(void) userdata;
}
void
quit(void)
{
@ -229,7 +275,8 @@ quit(void)
int
init(void)
{
if(SDL_Init(SDL_INIT_VIDEO) < 0)
SDL_AudioSpec as;
if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO) < 0)
return error("Init", SDL_GetError());
gWindow = SDL_CreateWindow("Uxn", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, WIDTH * ZOOM, HEIGHT * ZOOM, SDL_WINDOW_SHOWN);
if(gWindow == NULL)
@ -245,6 +292,15 @@ init(void)
clear(pixels);
SDL_StartTextInput();
SDL_ShowCursor(SDL_DISABLE);
as.freq = SAMPLE_FREQUENCY;
as.format = AUDIO_S16;
as.channels = 1;
as.callback = audio_callback;
as.samples = 2048;
audio_id = SDL_OpenAudioDevice(NULL, 0, &as, NULL, 0);
if(!audio_id)
return error("Audio", SDL_GetError());
SDL_PauseAudioDevice(audio_id, 0);
screen.x1 = PAD * 8;
screen.x2 = WIDTH - PAD * 8 - 1;
screen.y1 = PAD * 8;
@ -405,8 +461,16 @@ file_poke(Uxn *u, Uint16 ptr, Uint8 b0, Uint8 b1)
Uint8
audio_poke(Uxn *u, Uint16 ptr, Uint8 b0, Uint8 b1)
{
(void)u;
printf("%04x - %02x,%02x\n", ptr, b0, b1);
Uint8 *m = u->ram.dat;
if (b0 & 1) {
Uint16 channel_addr = ptr + (b0 & 0x6);
struct audio_channel *c = &channels[(b0 & 0x6) >> 1];
SDL_LockAudioDevice(audio_id);
c->period = note_periods[m[channel_addr + 8] % 12] >> (m[channel_addr + 8] / 12);
c->count %= c->period;
c->volume = m[channel_addr + 9] << 5;
SDL_UnlockAudioDevice(audio_id);
}
return b1;
}
@ -517,7 +581,7 @@ main(int argc, char **argv)
devkey = portuxn(&u, "key", ppnil);
devmouse = portuxn(&u, "mouse", ppnil);
portuxn(&u, "file", file_poke);
portuxn(&u, "audio", audio_poke);
devaudio = portuxn(&u, "audio", audio_poke);
portuxn(&u, "midi", ppnil);
portuxn(&u, "datetime", datetime_poke);
portuxn(&u, "---", ppnil);