diff options
Diffstat (limited to 'rgo/src/fndbyte.S')
| -rw-r--r-- | rgo/src/fndbyte.S | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/rgo/src/fndbyte.S b/rgo/src/fndbyte.S new file mode 100644 index 0000000..2e0ed8b --- /dev/null +++ b/rgo/src/fndbyte.S @@ -0,0 +1,44 @@ +/* + 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_fndbyte + +rgo_fndbyte: +#if defined(__x86_64__) + /* + rdi: void const * ptr + rsi: size_t num + dl: uint8_t byte + */ + /* rax: Address of the current element. */ + movq %rdi,%rax + /* rcx: Address of the element after the last element. */ + movq %rdi,%rcx + addq %rsi,%rcx + /* r8b: Current element. */ +.loop: + cmpq %rax,%rcx + je .nfnd /* We have went through the entire array without finding the byte. */ + movb (%rax),%r8b + cmpb %r8b,%dl + je .fnd /* We have found the byte. */ + incq %rax + jmp .loop +.fnd: + subq %rdi,%rax + ret +.nfnd: + movq $0xFFFFFFFFFFFFFFFF,%rax + ret +#endif |