/*
	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_fndchr

rgo_fndchr:
#if defined(__x86_64__)
	/*
		rdi: char const * str
		sil: char         chr
	*/
	/* rax: Address of the current character. */
	movq %rdi,%rax
	/* dl: Current character. */
.loop:
	movb (%rax),%dl
	cmpb %dl,%sil
	je .done /* Exit loop if we have found the character. */
	testb %dl,%dl
	je .err /* We encountered the null-terminator but not the specified character. */
	incq %rax
	jmp .loop
.done:
	subq %rdi,%rax
	ret
.err:
	movq $0xFFFFFFFFFFFFFFFF,%rax
	ret
#endif