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/*
* ========================
* ===== ===============
* ====== ================
* ====== ================
* ====== ==== ==== ==
* ====== === == = =
* ====== === = == =
* = === === = == ====
* = === === = == = =
* == ===== ==== ==
* ========================
*
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 2020-2021 Joe
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the organization nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOE ''AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL JOE BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* lowbat: asm/c_args.S
* Wed Feb 10 18:23:00 CET 2021
* Joe
*/
/*
* c_args(argc: rdi, *argv[]: rsi)
* -------------------------------
* returns 0 if args are invalid
* returns 1 if args are valid
*/
.text
.extern strncmp
.globl c_args
c_args:
cmp $0x2, %rdi
jle no_args
xorq %rax, %rax
pushq %rcx
xorq %rcx, %rcx
movb $0x8, %cl
movq (%rsi, %rcx, 2), %rax
cmpb $0x0, (%rax)
je no_args
pushq %rdi
movq (%rsi, %rcx, 1), %rdi
pushq %rsi
movq $reference, %rsi
pushq %rdx
xorq %rdx, %rdx
movb $0x6, %dl
callq strncmp
popq %rdx
popq %rsi
popq %rdi
popq %rcx
cmp $0x0, %rax
jne no_args
xorq %rax, %rax
movb $0x1, %al
jmp return
no_args:
xorq %rax, %rax
return:
retq
.data
reference: .asciz "--say"
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