# Copyright 2022-2023 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>.

.intel_syntax noprefix

.globl zap_fill

zap_fill:
	                   # zap_i8 val1;
	                   # zap_i04 val8;

	movzx   rax,sil    # val8 = val;
	shl     rax,0x8    # val8 <<= 0x8u;
	mov     al,sil     # val8 |= val;
	shl     rax,0x8    # val8 <<= 0x8u;
	mov     al,sil     # val8 |= val;
	shl     rax,0x8    # val8 <<= 0x8u;
	mov     al,sil     # val8 |= val;
	shl     rax,0x8    # val8 <<= 0x8u;
	mov     al,sil     # val8 |= val;
	shl     rax,0x8    # val8 <<= 0x8u;
	mov     al,sil     # val8 |= val;
	shl     rax,0x8    # val8 <<= 0x8u;
	mov     al,sil     # val8 |= val;
	shl     rax,0x8    # val8 <<= 0x8u;
	mov     al,sil     # val8 |= val;
	                   # val1 = val8;

.wrdfill:              # wrdfill:;
	cmp     rdx,0x8
	jl      .bytefill  # if (num < 0x8u) goto bytefill;

	mov     [rdi],rax  # *dest = val8;

	add     rdi,0x8    # dest += 0x8u;
	sub     rdx,0x8    # num -= 0x8u;
	jmp     .wrdfill   # goto wrdfill

.bytefill:             # bytefill:;
	test    rdx,rdx    # if (rem == 0x0)
	jz      .done      # goto done

	mov     [rsi],al   # *dest = val1;

	inc      rdi       # ++dest;
	dec      rdx       # --rem;
	jmp      .bytefill # goto bytefill;

.done:
	ret                # return