/*
	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