io.asm

; read_line(char* rcx, int rdx)
read_line:
    push rbp
    mov rbp, rsp
    sub rsp, 0x30

    ; Store RCX and RDX in the shadow space
    mov [rbp+0x10], rcx
    mov [rbp+0x18], rdx

    mov rcx, STD_INPUT_HANDLE	; Get handle to StdIn
    call GetStdHandle

    mov rcx, rax			    ; hFile
    mov rdx, [rbp + 0x10]		; lpBuffer
    mov r8, [rbp + 0x18]		; nNumberOfBytesToRead
    lea r9, [rbp - 0x08]		; lpNumberOfBytesRead

    mov qword [rbp - 0x08], 0	; lpOverlapped
    call ReadFile

    mov rax, [rbp - 0x08]       ; Put the number of bytes read in to rax

    sub rax, 0x02               ; Our "bytes read" includes the carriage return and line feed - so lets skip those

    mov rdx, [rbp + 0x10]       ; Load the buffer back into rdx
    mov byte [rdx + rax], 0x00  ; Null terminate the string after the main command (e.g, "exit\r\n" becomes "exit")

    leave
    ret

; write_line(char* rcx, int rdx)
write_line:
    push rbp
    mov rbp, rsp
    sub rsp, 0x30
    
    ; Store RCX and RDX in the shadow space
    mov [rbp + 0x10], rcx
    mov [rbp + 0x18], rdx

    mov rcx, STD_OUTPUT_HANDLE	; Get handle to StdOut
    call GetStdHandle

    mov rcx, rax			    ; hFile
    mov rdx, [rbp + 0x10]		; lpBuffer
    mov r8, [rbp + 0x18]		; nNumberOfBytesToRead
    lea r9, [rbp - 0x08]		; lpNumberOfBytesRead

    mov qword [rbp - 0x08], 0	; lpOverlapped
    call WriteFile

    leave
    ret