/*
	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 <zap/priv.h>

.globl zap_strlen

zap_strlen:

	/*
		char const * str
	*/

#if defined(__amd64__)

	# rax: Address of the current character.
	# rdx: Current character.

	movq %rdi,%rax

	# Iterate over the string:
.loop:

	# Move the character into a register:
	movb (%rax),%dl

	# Check if we have reached the null-terminator:
	testb %dl,%dl
	jz .done # If so, we are done.

	# Continue to the next character:
	incq %rax
	jmp .loop

	# Done:
.done:

	# Get the length:
	subq %rdi,%rax

	ret

#endif