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/*
Copyright 2022 Gabriel Jensen.
This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.
*/
#include <rgo.h>
.global rgo_fndbyte
rgo_fndbyte:
/*
void const * ptr
size_t num
uint8_t byte
*/
#if defined(__i386__)
/* eax: Address of the current element. */
movl 0x4(%esp),%eax
/* ecx: Address of the element after the last element. */
movl 0x8(%esp),%ecx
addl %eax,%ecx
/* edx: Byte value. */
movb 0xC(%esp),%dl
/* ebx: Current element. */
pushl %ebx
.loop:
cmpl %eax,%ecx
je .nfnd /* We have went through the entire array without finding the byte. */
movb (%eax),%bl
cmpb %bl,%dl
je .fnd /* We have found the byte. */
incl %eax
jmp .loop
.fnd:
popl %ebx
subl 0x4(%esp),%eax
ret
.nfnd:
popl %ebx
movl $0xFFFFFFFF,%eax
ret
#elif defined(__x86_64__)
/* rax: Address of the current element. */
movq %rdi,%rax
/* rsi: Address of the element after the last element. */
addq %rdi,%rsi
/* rcx: Current element. */
.loop:
cmpq %rax,%rsi
je .nfnd /* We have went through the entire array without finding the byte. */
movb (%rax),%cl
cmpb %cl,%dl
je .fnd /* We have found the byte. */
incq %rax
jmp .loop
.fnd:
subq %rdi,%rax
ret
.nfnd:
movq $0xFFFFFFFFFFFFFFFF,%rax
ret
#endif
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