# 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/.

.globl zap_memfill

zap_memfill:
# Address of the current element:
#define addr     %rdi
# Address of the element after the last element:
#define afterbuf %rsi
# Byte value:
#define val      %dl

	addq addr,afterbuf # afterbuf += addr // afterbuf contains the number of bytes

	# Iterate over buffer:
.loop:

	# Check if we have reached the final element:
	cmpq addr,afterbuf # if (addr == afterbuf)
	je .done           # goto done

	# Set the value of the current element:
	movb val,(addr) # *addr = val

	# Continue to next element:
	incq addr # ++addr
	jmp .loop # goto loop

	# Finish:
.done:

	ret # return