diff options
Diffstat (limited to 'arch/x86/machine/string.c')
-rw-r--r-- | arch/x86/machine/string.c | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/arch/x86/machine/string.c b/arch/x86/machine/string.c new file mode 100644 index 0000000..2ea8392 --- /dev/null +++ b/arch/x86/machine/string.c @@ -0,0 +1,87 @@ +/* + * Copyright (c) 2014 Richard Braun. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <kern/param.h> +#include <kern/stddef.h> +#include <kern/string.h> + +#ifdef ARCH_STRING_MEMCPY +void * +memcpy(void *dest, const void *src, size_t n) +{ + void *orig_dest; + + orig_dest = dest; + asm volatile("cld; rep movsb" : "+D" (dest), "+S" (src), "+c" (n)); + return orig_dest; +} +#endif /* ARCH_STRING_MEMCPY */ + +#ifdef ARCH_STRING_MEMMOVE +void * +memmove(void *dest, const void *src, size_t n) +{ + void *orig_dest; + + orig_dest = dest; + + if (dest <= src) + asm volatile("cld; rep movsb" : "+D" (dest), "+S" (src), "+c" (n)); + else { + dest += n - 1; + src += n - 1; + asm volatile("std; rep movsb" : "+D" (dest), "+S" (src), "+c" (n)); + } + + return orig_dest; +} +#endif /* ARCH_STRING_MEMMOVE */ + +#ifdef ARCH_STRING_MEMSET +void * +memset(void *s, int c, size_t n) +{ + void *orig_s; + + orig_s = s; + asm volatile("cld; rep stosb" : "+D" (s), "+c" (n) : "a" (c)); + return orig_s; +} +#endif /* ARCH_STRING_MEMSET */ + +#ifdef ARCH_STRING_MEMCMP +int +memcmp(const void *s1, const void *s2, size_t n) +{ + unsigned char zf, c1, c2; + + if (n == 0) + return 0; + + asm volatile("cld\n" + "repe cmpsb\n" + "sete %0\n" + : "=g" (zf), "+D" (s1), "+S" (s2), "+c" (n)); + + if (zf) + return 0; + + c1 = *(((const unsigned char *)s1) - 1); + c2 = *(((const unsigned char *)s2) - 1); + return (int)c1 - (int)c2; +} +#endif /* ARCH_STRING_MEMCMP */ |