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authorSimon Glass <sjg@chromium.org>2018-12-10 10:37:35 -0700
committerSimon Glass <sjg@chromium.org>2018-12-13 16:32:49 -0700
commite625b68b04a400ba377ec0a5b958bde0bc6244ff (patch)
tree0487b80bb20eac7868be358bec6f5446a7f4af67 /arch/sandbox/cpu
parente96fa6c91177d0aa81119d1d24cc0aa2dd663581 (diff)
dm: sandbox: Update sound to use two buffers
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>
Diffstat (limited to 'arch/sandbox/cpu')
-rw-r--r--arch/sandbox/cpu/sdl.c88
1 files changed, 63 insertions, 25 deletions
diff --git a/arch/sandbox/cpu/sdl.c b/arch/sandbox/cpu/sdl.c
index c7a8d94549..4dacdbf993 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;