proj3-1, v1

; Asks user for number between -25 and 25
; Asks the user for a string, must be longer than 8 characters long
; Shifts string

section .data
	promptShiftValue db "Enter a shift value between -25 and 25 (included) ", 10
    	lenPromptShiftValue equ $-promptShiftValue

	promptStringValue db "Enter a string greater than 8 characters ", 10
    	lenPromptStringValue equ $-promptStringValue

	currentMessageText db "Current message: ", 10
	lenCurrentMessageText equ $-currentMessageText

	shiftValueBuffer db 16        ; Buffer to store the input (2 digits + newline + null terminator)
    	stringBuffer db 16
	;result dw 0        ; Variable to store the converted integer result
    	lower dw -25
    	;upper dw 25
        my_char db 'A'

section .bss
	result resw 16  ; Reserve 2 bytes for result variable

section .text
	 global main

main:
	call _handleObtainingShiftValue
	call _handleObtainingString

	mov rax, 60
	mov rdi, 0
	syscall

_handleObtainingShiftValue:
        call _printObtainShiftValueText
        call _obtainShiftValue
        call _checkIfShiftValueValid
	ret

_handleObtainingString:
	call _printObtainStringText
	call _obtainString
	mov eax, 0
	call _countLoop
	ret

_handleCipher:
	call _printCurrentMessageText
	ret

_printObtainShiftValueText:
	mov rax, 1
        mov rdi, 1
        mov rsi, promptShiftValue
        mov rdx, 50
    	syscall
    	ret

_obtainShiftValue:
	; Get user input
   	mov rax, 0
   	mov rdi, 0
    	mov rsi, shiftValueBuffer
    	mov rdx, 16
    	syscall

        ; Convert input to ASCII
	xor ax, ax     			          ; Clear AX (accumulator)
	xor ecx, ecx  			          ; Clear ECX (loop counter)
	movzx esi, byte [shiftValueBuffer + ecx]  ; Get the first character

	; Check for minus sign character '-'
	cmp esi, 45
	je _handleNegative

_convertLoop:
	; Check if the character is a newline
	cmp byte [shiftValueBuffer + ecx], 10
	je _endConversion

	; Convert the character to a digit value
	sub esi, 0x30   ; Subtrac '0' to conver tot digit value

	; Multiply the accumulator by 10 and add the digit value
	imul ax, 10
	add ax, si

	; Move to the next character
	inc ecx
	movzx esi, byte [shiftValueBuffer + ecx]
	jmp _convertLoop

_handleNegative:
	; Move to the next character
	inc ecx
	movzx esi, byte [shiftValueBuffer + ecx]

	; Convert the remaining characters to an integer
	jmp _convertLoop

_endConversion:
	; Check if the number is negative
	cmp byte [shiftValueBuffer], 45
	je _makeNegative

	; Store the result
	mov [result], ax
	ret

_makeNegative:
	; Negate the result
	neg ax
	mov [result], ax

_checkIfShiftValueValid:
	xor bx, bx ; clear out bx
	mov [result], ax
	cmp ax, -25
	jl _handleObtainingShiftValue
	cmp ax, 25
	jg _handleObtainingShiftValue

	ret

_printObtainStringText:
	xor rsi, rsi
    	mov rax, 1
   	mov rdi, 1
    	mov rsi, promptStringValue
    	mov rdx, 42
    	syscall

	ret

_obtainString:
	mov rax, 0
	mov rdi, 0
	mov rsi, stringBuffer
	mov rdx, 8
	syscall

	ret

_countLoop:
	cmp byte [stringBuffer + rax], 0  ; Check for null terminator
	je _checkCount

	inc eax
	cmp eax, 8
	jle _countLoop

_checkCount:
	cmp eax, 8   ; Compare the character count with 8
	jle _handleObtainingString

	call _handleCipher

_printCurrentMessageText:
	mov rax, 1
	mov rdi, 1
	mov rsi, currentMessageText
	mov rdx, lenCurrentMessageText
	syscall

	ret