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LibC: Implement memcpy and memset for x86_64

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This commit is contained in:
Gunnar Beutner 2021-06-28 21:08:26 +02:00 • committed by Andreas Kling
parent 2a78bf8596
commit 086b7a4537
1 changed files with 8 additions and 19 deletions
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27
Userland/Libraries/LibC/string.cpp
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@ -111,7 +111,6 @@ int memcmp(const void* v1, const void* v2, size_t n)
return 0;
}
#if ARCH(I386)
void* memcpy(void* dest_ptr, const void* src_ptr, size_t n)
{
void* original_dest = dest_ptr;
@ -128,11 +127,19 @@ void* memset(void* dest_ptr, int c, size_t n)
if (!(dest & 0x3) && n >= 12) {
size_t size_ts = n / sizeof(size_t);
size_t expanded_c = explode_byte((u8)c);
#if ARCH(I386)
asm volatile(
"rep stosl\n"
: "=D"(dest)
: "D"(dest), "c"(size_ts), "a"(expanded_c)
: "memory");
#else
asm volatile(
"rep stosq\n"
: "=D"(dest)
: "D"(dest), "c"(size_ts), "a"(expanded_c)
: "memory");
#endif
n -= size_ts * sizeof(size_t);
if (n == 0)
return dest_ptr;
@ -144,24 +151,6 @@ void* memset(void* dest_ptr, int c, size_t n)
: "memory");
return dest_ptr;
}
#else
void* memcpy(void* dest_ptr, const void* src_ptr, size_t n)
{
auto* dest = (u8*)dest_ptr;
auto* src = (const u8*)src_ptr;
for (size_t i = 0; i < n; ++i)
dest[i] = src[i];
return dest_ptr;
}
void* memset(void* dest_ptr, int c, size_t n)
{
auto* dest = (u8*)dest_ptr;
for (size_t i = 0; i < n; ++i)
dest[i] = (u8)c;
return dest_ptr;
}
#endif
void* memmove(void* dest, const void* src, size_t n)
{