/**
* Mix PCM data from a given data source to a destination buffer
* (which already contains PCM data). The data which is read from the source
* buffer is and byte-swapped.
*
* Use this function, if the source is big endian and the destination
* is little endian, or vice versa.
*
* Performs cipping, if necessary.
*/
inline void ByteSwapAndMixPCM(int16_t *dest, const int16_t *src,
size_t num_frames, unsigned vol_percent) {
MixPCM(dest, num_frames, vol_percent,
[&src](size_t i) {
return static_cast<int32_t>(GenericByteSwap16(src[i]));
});
}
/**
* Mix PCM data from a given data source to a destination buffer
* (which already contains PCM data).
*
* Performs cipping, if necessary.
*/
inline void MixPCM(int16_t *dest, const int16_t *src, size_t num_frames,
unsigned vol_percent) {
MixPCM(dest, num_frames, vol_percent, [&src](size_t i) { return src[i]; });
}
size_t
PCMMixerDataSource::GetData(int16_t *buffer, size_t n)
{
size_t copied_count = 0;
PCMDataSource *sources_to_remove[MAX_MIXER_SOURCES_COUNT];
unsigned sources_to_remove_count = 0;
const std::lock_guard<Mutex> protect(lock);
for (unsigned i = 0; i < MAX_MIXER_SOURCES_COUNT; ++i) {
PCMDataSource *source = sources[i];
if (nullptr != source) {
bool do_byte_swap = ::IsBigEndian() != source->IsBigEndian();
if (0 == copied_count) {
copied_count = source->GetData(buffer, n);
if (0 == copied_count) {
sources_to_remove[sources_to_remove_count++] = source;
} else {
if (do_byte_swap)
ByteSwapAndLowerVolume(buffer, copied_count, vol_percent);
else
LowerVolume(buffer, copied_count, vol_percent);
}
} else {
int16_t temp_buffer[1024];
size_t current_src_copied_count = 0;
bool current_src_end = false;
while (!current_src_end && (current_src_copied_count < copied_count)) {
size_t bytes_to_read = std::min(copied_count - current_src_copied_count,
ARRAY_SIZE(temp_buffer));
size_t iteration_read_count =
source->GetData(temp_buffer, bytes_to_read);
if (do_byte_swap)
ByteSwapAndMixPCM(buffer + current_src_copied_count, temp_buffer,
iteration_read_count, vol_percent);
else
MixPCM(buffer + current_src_copied_count, temp_buffer,
iteration_read_count, vol_percent);
current_src_copied_count += iteration_read_count;
current_src_end = (iteration_read_count < bytes_to_read);
}
if (!current_src_end && (copied_count < n)) {
size_t bytes_to_read = n - copied_count;
size_t rest_read_count =
source->GetData(buffer + copied_count, bytes_to_read);
if (do_byte_swap)
ByteSwapAndLowerVolume(buffer + copied_count, rest_read_count,
vol_percent);
else
LowerVolume(buffer + copied_count, rest_read_count,
vol_percent);
copied_count += rest_read_count;
current_src_end = (rest_read_count < bytes_to_read);
}
if (current_src_end) {
sources_to_remove[sources_to_remove_count++] = source;
}
}
}
}
if (sources_to_remove_count > 0) {
for (unsigned i = 0; i < sources_to_remove_count; ++i) {
for (unsigned j = 0; j < MAX_MIXER_SOURCES_COUNT; ++j) {
if (sources_to_remove[i] == sources[j])
sources[j] = nullptr;
}
}
}
return copied_count;
}
