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wmme limit host buffer size to 32k. try to make host buffer size a factor of over-limit user buffer size. closes #189

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This commit is contained in:
rossb 2011-08-25 07:15:31 +00:00
commit 16f40db4c8
1 changed files with 92 additions and 37 deletions
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129
src/hostapi/wmme/pa_win_wmme.c
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@ -1368,6 +1368,48 @@ static unsigned long ComputeHostBufferCountForFixedBufferSizeFrames(
}
static unsigned long ComputeHostBufferSizeGivenHardUpperLimit(
unsigned long userFramesPerBuffer,
unsigned long absoluteMaximumBufferSizeFrames )
{
static unsigned long primes_[] = { 2, 3, 5, 7, 11, 13, 17, 19, 23,
29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 0 }; /* zero terminated */
unsigned long result = userFramesPerBuffer;
int i;
assert( absoluteMaximumBufferSizeFrames > 67 ); /* assume maximum is large and we're only factoring by small primes */
/* search for the largest integer factor of userFramesPerBuffer less
than or equal to absoluteMaximumBufferSizeFrames */
/* repeatedly divide by smallest prime factors until a buffer size
smaller than absoluteMaximumBufferSizeFrames is found */
while( result > absoluteMaximumBufferSizeFrames ){
/* search for the smallest prime factor of result */
for( i=0; primes_[i] != 0; ++i )
{
unsigned long p = primes_[i];
unsigned long divided = result / p;
if( divided*p == result )
{
result = divided;
break; /* continue with outer while loop */
}
}
if( primes_[i] == 0 )
{ /* loop failed to find a prime factor, return an approximate result */
unsigned long d = (userFramesPerBuffer + (absoluteMaximumBufferSizeFrames-1))
/ absoluteMaximumBufferSizeFrames;
return userFramesPerBuffer / d;
}
}
return result;
}
static PaError SelectHostBufferSizeFramesAndHostBufferCount(
unsigned long suggestedLatencyFrames,
unsigned long userFramesPerBuffer,
@ -1387,16 +1429,26 @@ static PaError SelectHostBufferSizeFramesAndHostBufferCount(
}else{
effectiveUserFramesPerBuffer = userFramesPerBuffer;
if( userFramesPerBuffer > absoluteMaximumBufferSizeFrames ){
if( effectiveUserFramesPerBuffer > absoluteMaximumBufferSizeFrames ){
/* user has requested a user buffer that's larger than absoluteMaximumBufferSizeFrames */
/* @todo FIXME/REVIEW right now we allow the user to request an oversize host buffer,
even though elsewhere in the code there are suggestions that oversize buffers
can cause crashes with some drivers. see http://www.portaudio.com/trac/ticket/189
*/
/* return paBufferTooBig; */
/* user has requested a user buffer that's larger than absoluteMaximumBufferSizeFrames.
try to choose a buffer size that is equal or smaller than absoluteMaximumBufferSizeFrames
but is also an integer factor of userFramesPerBuffer, so as to distribute computation evenly.
the buffer processor will handle the block adaption between host and user buffer sizes.
see http://www.portaudio.com/trac/ticket/189 for discussion.
*/
effectiveUserFramesPerBuffer = ComputeHostBufferSizeGivenHardUpperLimit( userFramesPerBuffer, absoluteMaximumBufferSizeFrames );
assert( effectiveUserFramesPerBuffer <= absoluteMaximumBufferSizeFrames );
/* try to ensure that duration of host buffering is at least as
large as duration of user buffer. */
if( suggestedLatencyFrames < userFramesPerBuffer )
suggestedLatencyFrames = userFramesPerBuffer;
}else{
effectiveUserFramesPerBuffer = userFramesPerBuffer;
}
}
@ -1407,39 +1459,42 @@ static PaError SelectHostBufferSizeFramesAndHostBufferCount(
*hostBufferCount = ComputeHostBufferCountForFixedBufferSizeFrames(
suggestedLatencyFrames, *hostBufferSizeFrames, minimumBufferCount );
/*
If there are too many host buffers we would like to coalesce
them by packing an integer number of user buffers into each host buffer.
We try to coalesce such that hostBufferCount will lie between
PA_MME_TARGET_HOST_BUFFER_COUNT_ and (PA_MME_TARGET_HOST_BUFFER_COUNT_*2)-1.
We limit coalescing to avoid exceeding either absoluteMaximumBufferSizeFrames and
preferredMaximumBufferSizeFrames.
First, compute a coalescing factor: the number of user buffers per host buffer.
The goal is to achieve PA_MME_TARGET_HOST_BUFFER_COUNT_ total buffer count.
Since our latency is computed based on (*hostBufferCount - 1) we compute a
coalescing factor based on (*hostBufferCount - 1) and (PA_MME_TARGET_HOST_BUFFER_COUNT_-1).
The + (PA_MME_TARGET_HOST_BUFFER_COUNT_-2) term below is intended to round up.
*/
numberOfUserBuffersPerHostBuffer = ((*hostBufferCount - 1) + (PA_MME_TARGET_HOST_BUFFER_COUNT_-2)) / (PA_MME_TARGET_HOST_BUFFER_COUNT_ - 1);
if( numberOfUserBuffersPerHostBuffer > 1 )
if( *hostBufferSizeFrames >= userFramesPerBuffer )
{
unsigned long maxCoalescedBufferSizeFrames = (absoluteMaximumBufferSizeFrames < preferredMaximumBufferSizeFrames) /* minimum of our limits */
? absoluteMaximumBufferSizeFrames
: preferredMaximumBufferSizeFrames;
/*
If there are too many host buffers we would like to coalesce
them by packing an integer number of user buffers into each host buffer.
We try to coalesce such that hostBufferCount will lie between
PA_MME_TARGET_HOST_BUFFER_COUNT_ and (PA_MME_TARGET_HOST_BUFFER_COUNT_*2)-1.
We limit coalescing to avoid exceeding either absoluteMaximumBufferSizeFrames and
preferredMaximumBufferSizeFrames.
unsigned long maxUserBuffersPerHostBuffer = maxCoalescedBufferSizeFrames / effectiveUserFramesPerBuffer; /* don't coalesce more than this */
First, compute a coalescing factor: the number of user buffers per host buffer.
The goal is to achieve PA_MME_TARGET_HOST_BUFFER_COUNT_ total buffer count.
Since our latency is computed based on (*hostBufferCount - 1) we compute a
coalescing factor based on (*hostBufferCount - 1) and (PA_MME_TARGET_HOST_BUFFER_COUNT_-1).
if( numberOfUserBuffersPerHostBuffer > maxUserBuffersPerHostBuffer )
numberOfUserBuffersPerHostBuffer = maxUserBuffersPerHostBuffer;
The + (PA_MME_TARGET_HOST_BUFFER_COUNT_-2) term below is intended to round up.
*/
numberOfUserBuffersPerHostBuffer = ((*hostBufferCount - 1) + (PA_MME_TARGET_HOST_BUFFER_COUNT_-2)) / (PA_MME_TARGET_HOST_BUFFER_COUNT_ - 1);
if( numberOfUserBuffersPerHostBuffer > 1 )
{
unsigned long maxCoalescedBufferSizeFrames = (absoluteMaximumBufferSizeFrames < preferredMaximumBufferSizeFrames) /* minimum of our limits */
? absoluteMaximumBufferSizeFrames
: preferredMaximumBufferSizeFrames;
*hostBufferSizeFrames = effectiveUserFramesPerBuffer * numberOfUserBuffersPerHostBuffer;
unsigned long maxUserBuffersPerHostBuffer = maxCoalescedBufferSizeFrames / effectiveUserFramesPerBuffer; /* don't coalesce more than this */
/* recompute hostBufferCount to approximate suggestedLatencyFrames now that hostBufferSizeFrames is larger */
*hostBufferCount = ComputeHostBufferCountForFixedBufferSizeFrames(
suggestedLatencyFrames, *hostBufferSizeFrames, minimumBufferCount );
if( numberOfUserBuffersPerHostBuffer > maxUserBuffersPerHostBuffer )
numberOfUserBuffersPerHostBuffer = maxUserBuffersPerHostBuffer;
*hostBufferSizeFrames = effectiveUserFramesPerBuffer * numberOfUserBuffersPerHostBuffer;
/* recompute hostBufferCount to approximate suggestedLatencyFrames now that hostBufferSizeFrames is larger */
*hostBufferCount = ComputeHostBufferCountForFixedBufferSizeFrames(
suggestedLatencyFrames, *hostBufferSizeFrames, minimumBufferCount );
}
}
return paNoError;