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lib: use 32-bit assignments for memset() 

SOF loves memset(). It takes great care to 0-initialise buffers and
objects. And its memset() routine only sets one byte at a time.
Optimise it to use 32-bit assignments where possible.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
This commit is contained in:
Guennadi Liakhovetski 2022-01-11 12:32:03 +01:00 committed by Liam Girdwood
parent 9abc285574
commit befc3d9a61
1 changed files with 19 additions and 1 deletions
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20
src/lib/lib.c
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@ -4,6 +4,7 @@
//
// Author: Liam Girdwood <liam.r.girdwood@linux.intel.com>
#include <sof/common.h>
#include <sof/string.h>
#include <sof/compiler_info.h>
@ -25,9 +26,26 @@ void *memset(void *s, int c, size_t n)
{
uint8_t *d8 = s;
uint8_t v = c;
uint32_t v32 = (uint32_t)v | ((uint32_t)v << 8) |
((uint32_t)v << 16) | ((uint32_t)v << 24);
uint32_t *d32 = (void *)ALIGN_UP((uintptr_t)s, sizeof(uint32_t));
/* Don't bother with 32-bit copies for up to 7 bytes */
size_t prefix_sz = n > 2 * sizeof(v32) - 1 ? (uint8_t *)d32 - d8 : n;
int i;
for (i = 0; i < n; i++)
for (i = 0; i < prefix_sz; i++)
d8[i] = v;
/* This won't be executed if n <= 7 */
for (i = 0; i < (n - prefix_sz) >> 2; i++)
d32[i] = v32;
/*
* The starting point now is the prefix plus the number of 32-bit copies
* from the loop above, multiplied by 4.
* This won't be executed if n <= 7
*/
for (i = prefix_sz + (i << 2); i < n; i++)
d8[i] = v;
return s;