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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_strcp
zap_strcp:
# Address of the current input character:
#define iaddr %rax
# Address of the first input character:
#define start %rdi
# Address of the current output character:
#define oaddr %rsi
# Current character:
#define chr %dl
movq start,iaddr
# Iterate over the strings:
.loop:
# Copy character:
movb (iaddr),chr # chr = *iaddr
movb chr,(oaddr) # *oaddr = chr
# Check if we have reached the null-terminator:
testb chr,chr # if (chr == 0x0)
jz .done # goto done
# Continue to the next character:
incq iaddr # ++iaddr
incq oaddr # ++oaddr
jmp .loop # goto loop
# Finish:
.done:
# Get the length of the (input) string:
subq start,iaddr # iaddr -= start
decq iaddr # --iaddr // We do not count the null-terminator in the string length.
ret # return iaddr
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