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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_fndchr
zap_fndchr:
# rdi: Address of the first character.
# rsi: Character to be found.
# rax: Address of the current character.
# rdx: Current character.
movq %rdi,%rax
# Iterate over the string:
.loop:
# Copy the character into a register:
movb (%rax),%dl
# Check if we have found the character:
cmpb %dl,%sil
je .fnd
# Check if we have found the null-terminator:
testb %dl,%dl
jz .nfnd
# Continue to the next character:
incq %rax
jmp .loop
# Found:
.fnd:
subq %rdi,%rax
ret
# Not found:
.nfnd:
movq $0xFFFFFFFFFFFFFFFF,%rax
ret
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