--- /dev/null
+/*
+ * (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);
+}