diff options
Diffstat (limited to 'rgo/src/strcpy.S')
| -rw-r--r-- | rgo/src/strcpy.S | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/rgo/src/strcpy.S b/rgo/src/strcpy.S new file mode 100644 index 0000000..f2fbc36 --- /dev/null +++ b/rgo/src/strcpy.S @@ -0,0 +1,39 @@ +/* + Copyright 2022 Gabriel Jensen + + This file is part of rgo. + + rgo is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. + + rgo 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 Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License along with rgo. If not, see <https://www.gnu.org/licenses/>. +*/ + +#include <rgo.h> + +.global rgo_strcpy + +rgo_strcpy: +#if defined(__x86_64__) + /* + rdi: char const * lstr + rsi: char const * rstr + */ + /* rax: Address of the current input character. */ + movq %rdi,%rax + /* rdx: Address of the current output character. */ + movq %rsi,%rdx + /* cl: Current character. */ +.loop: + movb (%rax),%cl + movb %cl,(%rdx) + testb %cl,%cl + jz .done + incq %rax + incq %rdx + jmp .loop +.done: + subq %rdi,%rax + ret +#endif |