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sdl: fix two bugs in ROCKBOXAUD_PlayAudio()

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First was an off-by-one bug in the loop over buffers. The condition was
`i < this->hidden->n_buffers', but should have been <=, not <. This wasn't
a critical issue, because the last iteration would check the currently
playing buffer - an unlikely situation.

The second logic bug would make the code always think it had found an empty
buffer, even when it had not, since `idx' was being unconditionally set
every loop, rendering it unusable for a sentinel value. Fix that.

Change-Id: I137330965d699acf827e59b6aa5c5f9ddf2ca617
This commit is contained in:
Franklin Wei 2020-08-08 00:43:05 -04:00 committed by Solomon Peachy
parent e232f69214
commit 4554b90859
1 changed files with 23 additions and 19 deletions
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42
apps/plugins/sdl/src/audio/rockbox/SDL_rockboxaudio.c
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@ -132,38 +132,42 @@ static void ROCKBOXAUD_WaitAudio(_THIS)
} }
/* when this is called, SDL wants us to play the samples in mixbuf */ /* when this is called, SDL wants us to play the samples in mixbuf */
static void ROCKBOXAUD_PlayAudio(_THIS) static void
ROCKBOXAUD_PlayAudio(_THIS)
{ {
/* There are two cases in which we should be called: /* There are two cases in which we should be called:
* - There is an empty buffer (marked with status = 0) * - There is an empty buffer (marked with status = 0)
* - There are more than two buffers marked as playing, meaning at least one is stale. * - There are more than two buffers marked as playing, meaning at least one is stale.
*/ */
int idx = -1;
/* Find the next empty or stale buffer and fill. */ /* Find the next empty or stale buffer and fill. */
for(int i = 1; i < this->hidden->n_buffers; ++i) for(int i = 1; i <= this->hidden->n_buffers; ++i)
{ {
idx = (this->hidden->current_playing + i) % this->hidden->n_buffers; int idx = (this->hidden->current_playing + i) % this->hidden->n_buffers;
/* Empty or stale. */ /* Empty or stale. */
if(this->hidden->status[idx] == 0 || if(this->hidden->status[idx] == 0 ||
this->hidden->status[idx] == 2) this->hidden->status[idx] == 2) {
break;
LOGF("found empty buffer: %d (status: %d)", idx, this->hidden->status[idx]);
/* probably premature optimization here */
char *dst = (char*)this->hidden->rb_buf[idx], *src = this->hidden->mixbuf;
int size = this->spec.size / 2;
memcpy(dst, src, size);
this->hidden->status[idx] = 1;
rb->yield();
memcpy(dst + size, src + size, this->spec.size - size);
LOGF("filled buffer %d (status %d %d %d %d)", idx, this->hidden->status[0], this->hidden->status[1], this->hidden->status[2], this->hidden->status[3]);
return;
}
} }
if(idx < 0)
return;
/* probably premature optimization here */ LOGF("WARNING: PlayDevice could not find buffer to fill; DROPPING SAMPLES!");
char *dst = (char*)this->hidden->rb_buf[idx], *src = this->hidden->mixbuf;
int size = this->hidden->mixlen / 2;
memcpy(dst, src, size);
this->hidden->status[idx] = 1;
rb->yield();
memcpy(dst + size, src + size, this->hidden->mixlen - size);
//LOGF("filled buffer %d (status %d %d %d)", idx, this->hidden->status[0], this->hidden->status[1], this->hidden->status[2]);
} }
static SDL_AudioDevice *ROCKBOXAUD_CreateDevice(int devindex) static SDL_AudioDevice *ROCKBOXAUD_CreateDevice(int devindex)