At present we use a single buffer for sound which means we cannot be playing one sound while queueing up the next. This wouldn't matter except that a long sound (more than a second) has to be created as a single buffer, thus using a lot of memory. To better mimic what real sound drivers do, add support for double buffering in sandbox.
Signed-off-by: Simon Glass sjg@chromium.org ---
Changes in v2: None
arch/sandbox/cpu/sdl.c | 88 ++++++++++++++++++++++++++++++------------ 1 file changed, 63 insertions(+), 25 deletions(-)
diff --git a/arch/sandbox/cpu/sdl.c b/arch/sandbox/cpu/sdl.c index c7a8d945492..4dacdbf993f 100644 --- a/arch/sandbox/cpu/sdl.c +++ b/arch/sandbox/cpu/sdl.c @@ -13,6 +13,21 @@ enum { SAMPLE_RATE = 22050, };
+/** + * struct buf_info - a data buffer holding audio data + * + * @pos: Current position playing in audio buffer + * @size: Size of data in audio buffer (0=empty) + * @alloced: Allocated size of audio buffer (max size it can hold) + * @data: Audio data + */ +struct buf_info { + uint pos; + uint size; + uint alloced; + uint8_t *data; +}; + static struct sdl_info { SDL_Surface *screen; int width; @@ -20,12 +35,11 @@ static struct sdl_info { int depth; int pitch; uint frequency; - uint audio_pos; - uint audio_size; uint sample_rate; - uint8_t *audio_data; bool audio_active; bool inited; + int cur_buf; + struct buf_info buf[2]; } sdl;
static void sandbox_sdl_poll_events(void) @@ -243,24 +257,37 @@ int sandbox_sdl_key_pressed(int keycode)
void sandbox_sdl_fill_audio(void *udata, Uint8 *stream, int len) { + struct buf_info *buf; int avail; + int i;
- avail = sdl.audio_size - sdl.audio_pos; - if (avail < len) - len = avail; - - SDL_MixAudio(stream, sdl.audio_data + sdl.audio_pos, len, - SDL_MIX_MAXVOLUME); - sdl.audio_pos += len; - - /* Loop if we are at the end */ - if (sdl.audio_pos == sdl.audio_size) - sdl.audio_pos = 0; + for (i = 0; i < 2; i++) { + buf = &sdl.buf[sdl.cur_buf]; + avail = buf->size - buf->pos; + if (avail <= 0) { + sdl.cur_buf = 1 - sdl.cur_buf; + continue; + } + if (avail > len) + avail = len; + + SDL_MixAudio(stream, buf->data + buf->pos, avail, + SDL_MIX_MAXVOLUME); + buf->pos += avail; + len -= avail; + + /* Move to next buffer if we are at the end */ + if (buf->pos == buf->size) + buf->size = 0; + else + break; + } }
int sandbox_sdl_sound_init(void) { SDL_AudioSpec wanted; + int i;
if (sandbox_sdl_ensure_init()) return -1; @@ -276,13 +303,20 @@ int sandbox_sdl_sound_init(void) wanted.callback = sandbox_sdl_fill_audio; wanted.userdata = NULL;
- sdl.audio_size = sizeof(uint16_t) * wanted.freq; - sdl.audio_data = malloc(sdl.audio_size); - if (!sdl.audio_data) { - printf("%s: Out of memory\n", __func__); - return -1; + for (i = 0; i < 2; i++) { + struct buf_info *buf = &sdl.buf[i]; + + buf->alloced = sizeof(uint16_t) * wanted.freq * wanted.channels; + buf->data = malloc(buf->alloced); + if (!buf->data) { + printf("%s: Out of memory\n", __func__); + if (i == 1) + free(sdl.buf[0].data); + return -1; + } + buf->pos = 0; + buf->size = 0; } - sdl.audio_pos = 0;
if (SDL_InitSubSystem(SDL_INIT_AUDIO) < 0) { printf("Unable to initialize SDL audio: %s\n", SDL_GetError()); @@ -296,23 +330,27 @@ int sandbox_sdl_sound_init(void) } sdl.audio_active = true; sdl.sample_rate = wanted.freq; + sdl.cur_buf = 0;
return 0;
err: - free(sdl.audio_data); + for (i = 0; i < 2; i++) + free(sdl.buf[i].data); return -1; }
int sandbox_sdl_sound_start(uint frequency) { + struct buf_info *buf = &sdl.buf[0]; + if (!sdl.audio_active) return -1; sdl.frequency = frequency; - sound_create_square_wave(sdl.sample_rate, - (unsigned short *)sdl.audio_data, - sdl.audio_size, frequency); - sdl.audio_pos = 0; + sound_create_square_wave(sdl.sample_rate, (unsigned short *)buf->data, + buf->alloced, frequency); + buf->pos = 0; + buf->size = buf->alloced; SDL_PauseAudio(0);
return 0;