Initial commit

File read and stored in two lists to stack memory

.gitignore

@@ -0,0 +1,4 @@
+*.o
+/gcc
+main
+main.out

Makefile

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+main: main.asm
+	nasm -g -f elf64 -o main.out main.asm
+	gcc -g -no-pie -nostartfiles -o main main.out

main.asm

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+  default rel
+  extern printf
+
+  global exitcode
+
+  section .data
+buf: dq 0
+dbuf: dw 0
+path:  db "./input.txt", 0
+nb_lines: dw 1000
+
+fmt:  db "Value %s: %d", 10, 0
+
+fd_str:  db "file descriptor", 0
+close_str:  db "close", 0
+content_str:  db "Content: '%s'", 10, 0
+nbr_str:  db "number", 0
+
+exitcode: dw 0
+
+
+
+  section .text
+
+  global _start
+
+
+printvalue:
+  push rbp
+  mov rbp, rsp
+  sub rsp, 8H
+
+  ;; args
+  mov dword [rbp-8H], edi
+  mov dword [rbp-4H], esi
+
+  ;; printf
+  xor rax, rax
+  lea rdi, [fmt]                ; format
+  mov esi, dword [rbp-8H]       ; arg1
+  mov edx, dword [rbp-4H]       ; arg2
+  call printf
+
+  ;; leave
+  mov rsp, rbp
+  pop rbp
+  ret
+;; End of printvalue
+
+readval:
+  ;; rdi: FILE DESCRIPTOR
+  ;; rsi: offset
+
+  push rbp
+  mov rbp, rsp
+  sub rsp, 16H
+
+  mov qword [rbp-8H], rsi
+  mov qword [rbp-16H], rdi
+
+  ;; sys_read
+  mov rax, 0                    ; sys_read
+  ;; rdi has already file descriptor
+  mov rdi, qword [rbp-16H]
+  mov rsi, buf
+  mov rdx, 5H
+  syscall
+
+  ;; Go to the next number
+  mov rax, 8                    ; sys_lseek
+  mov rdi, qword [rbp-16H]      ; fd
+  mov rsi, qword [rbp-8H]       ; advance by n chars
+  mov rdx, 1                    ; origin
+  syscall
+
+  ;; convert buf to an int
+  xor ebx, ebx
+  mov esi, buf
+  mov ecx, 5
+
+  .next_digit:
+  movzx eax, byte [esi]
+  inc rsi
+  sub al, '0'                   ; convert ascii to number (remove offset of the 0 digit)
+  imul ebx, 10
+  add ebx, eax                  ; rbx = rbx*10 + rax
+  loop .next_digit              ; loop until ecx = 0
+
+  xor rax, rax
+  mov eax, ebx
+
+  mov rsp, rbp
+  pop rbp
+  ret
+;; end of readval1
+
+
+_start:
+  push rbp
+  mov rbp, rsp
+  sub rsp, 2000H
+
+  ;; 8H -> 0 : file_descriptor
+  ;; 12H -> 8H : buffer for readvalue
+  ;; 14H -> 12H : current line
+  ;; 19H -> 17H: read loop counter
+  ;; 2000H -> 1060H : list 1 (1000 digits of 4 bytes)
+  ;; 1000H -> 60H : list 2
+
+
+  mov rax, 2                    ; sys_open
+  lea rdi, [path]
+  xor rsi, rsi
+  xor rdx, rdx
+  syscall
+
+  ;; store file descriptor
+  mov qword [rbp-8H], rax
+
+  ;; print file descriptor
+  lea rdi, [fd_str]
+  mov rsi, rax
+  call printvalue
+
+  ;; exit if open failed
+  cmp dword [rbp-8H], 0
+  jl exit
+
+  mov word [rbp-14H], 0H         ; line number
+
+  mov cx, [nb_lines]            ; number of lines
+loop:
+  mov [rbp-19H], cx             ; store loop counter
+
+  ;; read the 1st value
+  mov rdi, qword [rbp-8H]
+  mov rsi, 3H                   ; mov to the second number
+  call readval
+
+  ; store the read value
+  mov [dbuf], eax
+
+  ;; calculate list position
+  xor rax, rax
+  mov ax, word [rbp-14H]
+  mov bx, 2H
+  mul bx
+  ;; 14H -> 12H : line counter
+  mov rbx, 2000H
+  sub rbx, rax
+  mov r9, rbp
+  sub r9, rbx
+
+  ; move the value to its position
+  mov eax, [dbuf]
+  mov dword [r9], eax
+
+  ;; read the 2nd value
+  mov rdi, qword [rbp-8H]
+  mov rsi, 1H                   ; mov to the next line
+  call readval
+
+  ; store the read value
+  mov [dbuf], eax
+
+  ;; calculate list position
+  xor rax, rax
+  mov ax, word [rbp-14H]
+  mov bx, 4H
+  mul bx
+  mov rbx, 1000H
+  sub rbx, rax
+  mov r9, rbp
+  sub r9, rbx
+
+  ; move the value to its position
+  mov eax, [dbuf]
+  mov dword [r9], eax
+
+  xor rax, rax
+  mov ax, word [rbp-14H]
+  inc ax
+  mov word [rbp-14H], ax
+
+  mov cx, [rbp-19H]             ; restore loop counter
+  dec cx
+  jnz loop
+
+  ;; print values
+
+  mov word [rbp-14H], 0         ; line number
+  xor ecx, ecx
+  mov ecx, 2024                 ; There are 24 dword between address 1060H and 1000H
+
+  .loop:
+  mov [rbp-19H], cx             ; store loop counter
+
+  ;; calculate list 1 position
+  xor rax, rax
+  mov ax, word [rbp-14H]
+  mov bx, 4H
+  mul bx
+  mov rbx, 2000H
+  sub rbx, rax
+  mov r9, rbp
+  sub r9, rbx
+
+  ; move the value to its position
+  lea rdi, [nbr_str]
+  mov esi, dword [r9]
+  call printvalue
+
+  inc word [rbp-14H]
+
+  mov cx, [rbp-19H]
+  loop .loop
+
+
+close_file:
+  ;; sys_close
+  mov rax, 3                    ; sys_close
+  mov edi, dword [rbp-8H]
+  syscall
+
+  ;; print sys_close result
+  lea rdi, [close_str]
+  mov rsi, rax
+  call printvalue
+
+
+exit:
+  ;; EXIT
+  mov rax, 60                   ; sys_exit
+  mov rdi, [exitcode]
+  syscall
+