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# 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_memfnd
zap_memfnd:
# Address of the current element:
#define addr %rax
# Address of the first element:
#define start %rdi
# Address of the element after the last element:
#define afterbuf %rsi
# Byte value:
#define cmp %dl
# Current byte:
#define val %cl
movq start,addr # addr = start
addq start,afterbuf # afterbuf += start
# Iterate over the array:
.loop:
# Check if we have reached the end of the array:
cmpq addr,afterbuf # if (addr == afterbuf)
je .nfnd # goto nfnd
# Check if we have found the byte value:
movb (addr),val # val = *addr
cmpb val,cmp # if (val == cmp)
je .fnd # goto fnd
# Continue to the next byte:
incq addr # ++addr
jmp .loop # goto loop
# Found:
.fnd:
# Get the offset of the byte:
subq start,addr # addr -= start
ret # return addr
# Not found:
.nfnd:
movq $0xFFFFFFFFFFFFFFFF,addr # addr = 0xFFFFFFFFFFFFFFFF
ret # return addr
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