support multiple sound drivers, add sdl

2025-09-07 07:38:04 -04:00 · 2013-06-23 22:23:57 +03:00 · 2013-06-23 22:23:57 +03:00 · 26d3ca0d29
commit 26d3ca0d29
parent 20b143089c
6 changed files with 294 additions and 6 deletions
--- a/sndout_sdl.c
+++ b/sndout_sdl.c
@ -0,0 +1,151 @@
+/*
+ * (C) notaz, 2013
+ *
+ * This work is licensed under the terms of any of these licenses
+ * (at your option):
+ *  - GNU GPL, version 2 or later.
+ *  - GNU LGPL, version 2.1 or later.
+ *  - MAME license.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include <SDL.h>
+#include "sndout_sdl.h"
+
+// ~1/3s at 44kHz
+// set this to power of 2
+#define BUF_LEN 32768
+#define BUF_MASK (BUF_LEN - 1)
+
+static short buf[BUF_LEN];
+static int buf_w, buf_r;
+static int started;
+
+static void callback(void *userdata, Uint8 *stream, int len)
+{
+	int have = (buf_w - buf_r) & BUF_MASK;
+	int buf_left = BUF_LEN - buf_r;
+
+	len /= 2;
+	if (have > len)
+		have = len;
+	if (have > 0) {
+		if (have > buf_left) {
+			memcpy(stream, buf + buf_r, buf_left * 2);
+			stream += buf_left * 2;
+			buf_r = 0;
+			have -= buf_left;
+			len -= buf_left;
+		}
+		memcpy(stream, buf + buf_r, have * 2);
+		stream += have * 2;
+		buf_r = (buf_r + have) & BUF_MASK;
+		len -= have;
+	}
+
+	if (len > 0) {
+		// put in some silence..
+		memset(stream, 0, len * 2);
+	}
+}
+
+int sndout_sdl_init(void)
+{
+	int ret;
+
+	ret = SDL_InitSubSystem(SDL_INIT_AUDIO);
+	if (ret != 0)
+		return -1;
+
+	return 0;
+}
+
+int sndout_sdl_start(int rate, int stereo)
+{
+	SDL_AudioSpec desired;
+	int samples, shift;
+	int ret;
+
+	if (started)
+		sndout_sdl_stop();
+
+	desired.freq = rate;
+	desired.format = AUDIO_S16LSB;
+	desired.channels = stereo ? 2 : 1;
+	desired.callback = callback;
+	desired.userdata = NULL;
+
+	samples = rate * 4 * 16 / 1000;
+	for (shift = 8; (1 << shift) < samples; shift++)
+		;
+	desired.samples = 1 << shift;
+
+	ret = SDL_OpenAudio(&desired, NULL);
+	if (ret != 0) {
+		fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());
+		return -1;
+	}
+
+	buf_w = buf_r = 0;
+
+	SDL_PauseAudio(0);
+	started = 1;
+
+	return 0;
+}
+
+void sndout_sdl_stop(void)
+{
+	SDL_PauseAudio(1);
+	SDL_CloseAudio();
+	started = 0;
+}
+
+void sndout_sdl_wait(void)
+{
+	int left;
+
+	while (1)
+	{
+		left = (buf_r - buf_w - 2) & BUF_MASK;
+		if (left >= BUF_LEN / 2)
+			break;
+
+		SDL_Delay(4);
+	}
+}
+
+int sndout_sdl_write_nb(const void *samples, int len)
+{
+	int maxlen = (buf_r - buf_w - 2) & BUF_MASK;
+	int buf_left = BUF_LEN - buf_w;
+	int retval;
+
+	len /= 2;
+	if (len > maxlen)
+		// not enough space
+		len = maxlen;
+	if (len == 0)
+		// totally full
+		return 0;
+
+	retval = len;
+
+	if (len > buf_left) {
+		memcpy(buf + buf_w, samples, buf_left * 2);
+		samples = (const short *)samples + buf_left;
+		len -= buf_left;
+		buf_w = 0;
+	}
+	memcpy(buf + buf_w, samples, len * 2);
+	buf_w = (buf_w + len) & BUF_MASK;
+
+	return retval;
+}
+
+void sndout_sdl_exit(void)
+{
+	if (started)
+		sndout_sdl_stop();
+	SDL_QuitSubSystem(SDL_INIT_AUDIO);
+}