ae

.gitignore

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+bin/*
+tmp/*

build.sh

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+set -ex
+
+echo "compiling true"
+nasm -f elf64 -o tmp/true.o src/true/true.asm
+ld -s --nmagic -o bin/true tmp/true.o
+ls -l bin/true
+
+echo "compiling false"
+nasm -f elf64 -o tmp/false.o src/false/false.asm
+ld -s --nmagic -o bin/false tmp/false.o
+ls -l bin/false
+
+echo "compiling cat"
+nasm -f elf64 -o tmp/cat.o src/cat/cat.asm
+ld -s -o bin/cat tmp/cat.o
+ls -l bin/cat

src/cat/cat.asm

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+%define STDOUT 1
+%define STDERR 2
+
+%define SYS_READ 0
+%define SYS_WRITE 1
+%define SYS_OPEN 2
+%define SYS_CLOSE 3
+%define SYS_EXIT 60
+
+%define O_RDONLY 0
+
+section .bss
+    buf resb 4096
+
+section .data
+    file_err_m db "file error", 10, 0
+    args_err_m db "args error", 10, 0
+
+section .text
+global _start
+
+_start:
+    ; так ну для начала надо бы понять сколько у нас аргументов
+    mov rbx, [rsp]
+    cmp rbx, 1
+    je .prep_narg
+    cmp rbx, 2
+    jne args_err
+    jmp .prep
+.prep_narg:
+    xor r12, r12
+    jmp .loop
+.prep:
+    mov rax, SYS_OPEN
+    mov rdi, [rsp + 16]; argv[1]
+    mov rsi, O_RDONLY
+    xor rdx, rdx
+    syscall
+    js file_err
+
+    mov r12, rax
+.loop:
+    mov rax, SYS_READ
+    mov rdi, r12
+    mov rsi, buf
+    mov rdx, 4096
+    syscall
+
+    test rax, rax
+    jz .done
+
+    mov rdx, rax
+    mov rax, SYS_WRITE
+    mov rdi, STDOUT
+    mov rsi, buf
+    syscall
+    jmp .loop
+.done:
+    mov rax, SYS_CLOSE
+    mov rdi, r12
+    syscall
+    jmp exit
+
+file_err:
+    mov rax, SYS_WRITE
+    mov rdi, STDERR
+    mov rsi, file_err_m
+    mov rdx, 12
+    syscall
+
+    jmp exit_err
+
+args_err:
+    mov rax, SYS_WRITE
+    mov rdi, STDERR
+    mov rsi, args_err_m
+    mov edx, 12
+    syscall
+
+    jmp exit_err
+
+exit_err:
+    mov rax, SYS_EXIT
+    mov rdi, 1
+    syscall
+
+exit:
+    mov rax, SYS_EXIT
+    mov rdi, 0
+    syscall

src/false/false.asm

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+section .text
+global _start
+
+_start:
+    mov rax, 60
+    mov rdi, 1
+    syscall

src/true/true.asm

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+section .text
+global _start
+
+_start:
+    mov rax, 60
+    xor rdi, rsi
+    syscall