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alsa: Cleaned up the 5.1 swizzle mess a little.

Shouldn't this be something ALSA handles for us with channel maps, so we can
just delete this code?
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icculus committed Aug 2, 2016
1 parent 6bd1ec6 commit 754efd43f4574df0e78716d0e72226c32b75993d
Showing with 23 additions and 26 deletions.
  1. +23 −26 src/audio/alsa/SDL_alsa_audio.c
@@ -241,37 +241,37 @@ ALSA_WaitDevice(_THIS)
* "For Linux ALSA, this is FL-FR-RL-RR-C-LFE
* and for Windows DirectX [and CoreAudio], this is FL-FR-C-LFE-RL-RR"
*/
#define SWIZ6(T) \
T *ptr = (T *) this->hidden->mixbuf; \
#define SWIZ6(T, buf, numframes) \
T *ptr = (T *) buf; \
Uint32 i; \
for (i = 0; i < this->spec.samples; i++, ptr += 6) { \
for (i = 0; i < numframes; i++, ptr += 6) { \
T tmp; \
tmp = ptr[2]; ptr[2] = ptr[4]; ptr[4] = tmp; \
tmp = ptr[3]; ptr[3] = ptr[5]; ptr[5] = tmp; \
}

static SDL_INLINE void
swizzle_alsa_channels_6_64bit(_THIS)
swizzle_alsa_channels_6_64bit(void *buffer, Uint32 bufferlen)
{
SWIZ6(Uint64);
SWIZ6(Uint64, buffer, bufferlen);
}

static SDL_INLINE void
swizzle_alsa_channels_6_32bit(_THIS)
swizzle_alsa_channels_6_32bit(void *buffer, Uint32 bufferlen)
{
SWIZ6(Uint32);
SWIZ6(Uint32, buffer, bufferlen);
}

static SDL_INLINE void
swizzle_alsa_channels_6_16bit(_THIS)
swizzle_alsa_channels_6_16bit(void *buffer, Uint32 bufferlen)
{
SWIZ6(Uint16);
SWIZ6(Uint16, buffer, bufferlen);
}

static SDL_INLINE void
swizzle_alsa_channels_6_8bit(_THIS)
swizzle_alsa_channels_6_8bit(void *buffer, Uint32 bufferlen)
{
SWIZ6(Uint8);
SWIZ6(Uint8, buffer, bufferlen);
}

#undef SWIZ6
@@ -282,18 +282,16 @@ swizzle_alsa_channels_6_8bit(_THIS)
* channels from Windows/Mac order to the format alsalib will want.
*/
static SDL_INLINE void
swizzle_alsa_channels(_THIS)
swizzle_alsa_channels(_THIS, void *buffer, Uint32 bufferlen)
{
if (this->spec.channels == 6) {
const Uint16 fmtsize = (this->spec.format & 0xFF); /* bits/channel. */
if (fmtsize == 16)
swizzle_alsa_channels_6_16bit(this);
else if (fmtsize == 8)
swizzle_alsa_channels_6_8bit(this);
else if (fmtsize == 32)
swizzle_alsa_channels_6_32bit(this);
else if (fmtsize == 64)
swizzle_alsa_channels_6_64bit(this);
switch (SDL_AUDIO_BITSIZE(this->spec.format)) {
case 8: swizzle_alsa_channels_6_8bit(buffer, bufferlen); break;
case 16: swizzle_alsa_channels_6_16bit(buffer, bufferlen); break;
case 32: swizzle_alsa_channels_6_32bit(buffer, bufferlen); break;
case 64: swizzle_alsa_channels_6_64bit(buffer, bufferlen); break;
default: SDL_assert(!"unhandled bitsize"); break;
}
}

/* !!! FIXME: update this for 7.1 if needed, later. */
@@ -303,19 +301,18 @@ swizzle_alsa_channels(_THIS)
static void
ALSA_PlayDevice(_THIS)
{
int status;
const Uint8 *sample_buf = (const Uint8 *) this->hidden->mixbuf;
const int frame_size = (((int) (this->spec.format & 0xFF)) / 8) *
const int frame_size = (((int) SDL_AUDIO_BITSIZE(this->spec.format)) / 8) *
this->spec.channels;
snd_pcm_uframes_t frames_left = ((snd_pcm_uframes_t) this->spec.samples);

swizzle_alsa_channels(this);
swizzle_alsa_channels(this, this->hidden->mixbuf, frames_left);

while ( frames_left > 0 && SDL_AtomicGet(&this->enabled) ) {
/* !!! FIXME: This works, but needs more testing before going live */
/* ALSA_snd_pcm_wait(this->hidden->pcm_handle, -1); */
status = ALSA_snd_pcm_writei(this->hidden->pcm_handle,
sample_buf, frames_left);
int status = ALSA_snd_pcm_writei(this->hidden->pcm_handle,
sample_buf, frames_left);

if (status < 0) {
if (status == -EAGAIN) {

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