diff options
Diffstat (limited to 'asm/c_args.S')
| -rw-r--r-- | asm/c_args.S | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/asm/c_args.S b/asm/c_args.S new file mode 100644 index 0000000..dabffd3 --- /dev/null +++ b/asm/c_args.S @@ -0,0 +1,92 @@ +/* + * ======================== + * ===== =============== + * ====== ================ + * ====== ================ + * ====== ==== ==== == + * ====== === == = = + * ====== === = == = + * = === === = == ==== + * = === === = == = = + * == ===== ==== == + * ======================== + * + * 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" |