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hw/audio/cs4231a: skip automatic zero-init of large arrays

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The 'cs_write_audio' method has a pair of byte arrays, one 4k in size
and one 8k, which are used in converting audio samples. Skip the
automatic zero-init of these arrays to eliminate the performance
overhead in the I/O hot path.

The 'tmpbuf' array will be fully initialized when reading a block of
data from the guest. The 'linbuf' array will be fully initialized
when converting the audio samples.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20250610123709.835102-9-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Daniel P. Berrangé 2025-06-10 13:36:46 +01:00 • committed by Stefan Hajnoczi
parent 2553d2d26a
commit ca2cc0385d
1 changed files with 2 additions and 2 deletions
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4
hw/audio/cs4231a.c
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@ -528,7 +528,7 @@ static int cs_write_audio (CSState *s, int nchan, int dma_pos,
int dma_len, int len) int dma_len, int len)
{ {
int temp, net; int temp, net;
uint8_t tmpbuf[4096]; QEMU_UNINITIALIZED uint8_t tmpbuf[4096];
IsaDmaClass *k = ISADMA_GET_CLASS(s->isa_dma); IsaDmaClass *k = ISADMA_GET_CLASS(s->isa_dma);
temp = len; temp = len;
@ -547,7 +547,7 @@ static int cs_write_audio (CSState *s, int nchan, int dma_pos,
copied = k->read_memory(s->isa_dma, nchan, tmpbuf, dma_pos, to_copy); copied = k->read_memory(s->isa_dma, nchan, tmpbuf, dma_pos, to_copy);
if (s->tab) { if (s->tab) {
int i; int i;
int16_t linbuf[4096]; QEMU_UNINITIALIZED int16_t linbuf[4096];
for (i = 0; i < copied; ++i) for (i = 0; i < copied; ++i)
linbuf[i] = s->tab[tmpbuf[i]]; linbuf[i] = s->tab[tmpbuf[i]];