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Abandon POT buffer sizes only for dsound.

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Allows more fine tuned latencies.
This commit is contained in:
Themaister 2011-08-05 19:17:33 +02:00
parent 9aef33aabd
commit 706a3738b5
1 changed files with 12 additions and 8 deletions
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20
audio/dsound.c
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@ -41,9 +41,9 @@ typedef struct dsound
unsigned buffer_size; unsigned buffer_size;
} dsound_t; } dsound_t;
static inline unsigned write_avail(unsigned read_ptr, unsigned write_ptr, unsigned buffer_mask) static inline unsigned write_avail(unsigned read_ptr, unsigned write_ptr, unsigned buffer_size)
{ {
return (read_ptr + buffer_mask + 1 - write_ptr) & buffer_mask; return (read_ptr + buffer_size - write_ptr) % buffer_size;
} }
static inline void get_positions(dsound_t *ds, DWORD *read_ptr, DWORD *write_ptr) static inline void get_positions(dsound_t *ds, DWORD *read_ptr, DWORD *write_ptr)
@ -115,17 +115,16 @@ static DWORD CALLBACK dsound_thread(PVOID data)
dsound_t *ds = data; dsound_t *ds = data;
SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_TIME_CRITICAL); SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_TIME_CRITICAL);
unsigned buffer_mask = ds->buffer_size - 1;
DWORD write_ptr; DWORD write_ptr;
get_positions(ds, NULL, &write_ptr); get_positions(ds, NULL, &write_ptr);
write_ptr = (write_ptr + ds->buffer_size / 2) & buffer_mask; write_ptr = (write_ptr + ds->buffer_size / 2) % ds->buffer_size;
while (ds->thread_alive) while (ds->thread_alive)
{ {
DWORD read_ptr; DWORD read_ptr;
get_positions(ds, &read_ptr, NULL); get_positions(ds, &read_ptr, NULL);
DWORD avail = write_avail(read_ptr, write_ptr, buffer_mask); DWORD avail = write_avail(read_ptr, write_ptr, ds->buffer_size);
EnterCriticalSection(&ds->crit); EnterCriticalSection(&ds->crit);
DWORD fifo_avail = fifo_read_avail(ds->buffer); DWORD fifo_avail = fifo_read_avail(ds->buffer);
@ -152,7 +151,7 @@ static DWORD CALLBACK dsound_thread(PVOID data)
memset(region.chunk2, 0, region.size2); memset(region.chunk2, 0, region.size2);
release_region(ds, &region); release_region(ds, &region);
write_ptr = (write_ptr + region.size1 + region.size2) & buffer_mask; write_ptr = (write_ptr + region.size1 + region.size2) % ds->buffer_size;
} }
else // All is good. Pull from it and notify FIFO :D else // All is good. Pull from it and notify FIFO :D
{ {
@ -172,7 +171,7 @@ static DWORD CALLBACK dsound_thread(PVOID data)
LeaveCriticalSection(&ds->crit); LeaveCriticalSection(&ds->crit);
release_region(ds, &region); release_region(ds, &region);
write_ptr = (write_ptr + region.size1 + region.size2) & buffer_mask; write_ptr = (write_ptr + region.size1 + region.size2) % ds->buffer_size;
SetEvent(ds->event); SetEvent(ds->event);
} }
@ -274,7 +273,12 @@ static void* dsound_init(const char *device, unsigned rate, unsigned latency)
.nAvgBytesPerSec = rate * 2 * sizeof(int16_t), .nAvgBytesPerSec = rate * 2 * sizeof(int16_t),
}; };
ds->buffer_size = next_pow2((latency * wfx.nAvgBytesPerSec) / 1000); ds->buffer_size = (latency * wfx.nAvgBytesPerSec) / 1000;
ds->buffer_size /= CHUNK_SIZE;
ds->buffer_size *= CHUNK_SIZE;
if (ds->buffer_size < 4 * CHUNK_SIZE)
ds->buffer_size = 4 * CHUNK_SIZE;
SSNES_LOG("[DirectSound]: Setting buffer size of %u bytes\n", ds->buffer_size); SSNES_LOG("[DirectSound]: Setting buffer size of %u bytes\n", ds->buffer_size);
SSNES_LOG("[DirectSound]: Latency = %u ms\n", (unsigned)((1000 * ds->buffer_size) / wfx.nAvgBytesPerSec)); SSNES_LOG("[DirectSound]: Latency = %u ms\n", (unsigned)((1000 * ds->buffer_size) / wfx.nAvgBytesPerSec));