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hv: refine memset

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Use enhanced rep fast-string operation to refine memset.

Tracked-On: #861
Signed-off-by: Li, Fei1 <fei1.li@intel.com>
This commit is contained in:
Li, Fei1 2018-12-17 21:52:52 +08:00 committed by wenlingz
parent 78e9a84f39
commit f9897c6f4e
1 changed files with 14 additions and 25 deletions
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39
hypervisor/lib/memory.c
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@ -367,33 +367,22 @@ void *memcpy_s(void *d, size_t dmax, const void *s, size_t slen_arg)
return d;
}
static inline void memset_erms(void *base, uint8_t v, size_t n)
{
asm volatile("rep ; stosb"
: "+D"(base)
: "a" (v), "c"(n));
}
void *memset(void *base, uint8_t v, size_t n)
{
uint8_t *dest_p;
size_t n_q;
size_t count;
void *ret;
dest_p = (uint8_t *)base;
if ((dest_p == NULL) || (n == 0U)) {
ret = NULL;
} else {
/* do the few bytes to get uint64_t alignment */
count = n;
for (; (count != 0U) && (((uint64_t)dest_p & 7UL) != 0UL); count--) {
*dest_p = v;
dest_p++;
}
/* 64-bit mode */
n_q = count >> 3U;
asm volatile("cld ; rep ; stosq ; movl %3,%%ecx ; rep ; stosb"
: "+c"(n_q), "+D"(dest_p)
: "a" (v * 0x0101010101010101U),
"r"((uint32_t)count & 7U));
ret = (void *)dest_p;
/*
* Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended
* to use it when possible.
*/
if ((base != NULL) && (n != 0U)) {
memset_erms(base, v, n);
}
return ret;
return base;
}