asm nikita

extrn GetStdHandle: proc,
	WriteConsoleA: proc,
	ReadConsoleA: proc,
	lstrlenA: proc,
	ExitProcess: proc

.data
	STACKALLOC macro arg
		push R15
		mov R15, RSP
		sub RSP, 8 * 4
		if arg
			sub RSP, 8 * arg
		endif
		and SPL, 0F0h
	endm

	STACKFREE macro
		mov RSP, R15
		pop R15
	endm

	NULL_FIFTH_ARG macro
		mov qword ptr[RSP + 20h], 0
	endm

	STD_OUTPUT_HANDLE equ -11
	STD_INPUT_HANDLE equ -10

	hStdInput dq 0
	hStdOutput dq 0
	sum dq 0
	aOutputHandle db 'a = ', 0
	bOutputHandle db 'b = ', 0
	sumOutputHandle db 'a + b = ', 0
	invalid db 'Invalid character', 0
	continue db 'Press any key to exit...', 0

.code
	Start proc
		STACKALLOC 1
		mov RCX, STD_OUTPUT_HANDLE
		call GetStdHandle
		mov hStdOutput, RAX

		mov RCX, STD_INPUT_HANDLE
		call GetStdHandle
		mov hStdInput, RAX

		lea RAX, aOutputHandle
		push RAX
		call StringWrite

		call StringRead
		cmp R10, 0
		je invalidCharacter
		mov R8, RAX

		lea RAX, bOutputHandle
		push RAX
		call StringWrite

		call StringRead
		cmp R10, 0
		je invalidCharacter
		add R8, RAX

		lea RAX, sumOutputHandle
		push RAX
		call StringWrite

		mov RAX, R8
		push RAX
		call PrintSignedNumber

		lea RAX, continue
		push RAX
		call StringWrite

		call inputAwaiting
		call ExitProcess

		invalidCharacter:
		lea RAX, invalid
		push RAX
		call StringWrite

		lea RAX, continue
		push RAX
		call StringWrite

		call ExitProcess
	Start endp

	StringWrite proc uses RAX RCX RDX R8 R9 R10 R11, string: qword
		local bytesWritten: qword

		STACKALLOC 1

		mov RCX, string
		call lstrlenA

		mov RCX, hStdOutput
		mov RDX, string
		mov R8, RAX
		lea R9, bytesWritten

		NULL_FIFTH_ARG
		call WriteConsoleA
		STACKFREE
		ret 8
	StringWrite endp

	StringRead proc uses RBX RCX RDX R8 R9 R10 R11
		local readStr[64]: byte,
			bytesRead: dword
		STACKALLOC 1

		mov RCX, hStdInput
		lea RDX, readStr
		mov R8, 64
		lea R9, bytesRead
		NULL_FIFTH_ARG

		call ReadConsoleA

		xor RCX, RCX
		mov ECX, bytesRead
		sub ECX, 2
		mov readStr[RCX], 0
		xor RBX, RBX
		mov R8, 1

		strReading:
		dec RCX
		cmp RCX, -1
		je scanningComplete
		mov RAX, 0
		mov AL, readStr[RCX]
		cmp AL, '-'
		jne eval
		neg RBX
		jmp scanningComplete

		eval:
		cmp AL, 30h
		jl error
		cmp AL, 39h
		jg error
		add RBX, RAX

		sub RAX, 30h
		mul R8
		add RBX, RAX
		mov RAX, 10
		mul R8
		mov R8, RAX

		error:
		xor R10, R10
		STACKFREE
		ret

		scanningComplete:
		mov R10, 1
		mov RAX, RBX
		STACKFREE
		ret
	StringRead endp

	PrintSignedNumber proc uses RAX RCX RDX R8 R9 R10 R11, number: qword
		local numberStr[22]: byte
		xor R8, R8
		mov RAX, sum
		btc number, 63
		inc R8
		neg RAX
		mov RBX, 10
		xor RCX, RCX

		digitDivision:
		xor RDX, RDX
		div RBX
		add RDX, '0'
		push RDX
		inc RCX
		cmp RAX, 0
		jne digitDivision
		jmp prohodPoStacky

		prohodPoStacky:
		pop RDX
		mov numberStr[R8], DL
		inc R8
		cmp RCX, 0
		jne prohodPoStacky
		mov numberStr[R8], 0
		lea RAX, numberStr
		push RAX
		ret 8
	PrintSignedNumber endp

	inputAwaiting proc uses RAX RCX RDX R8 R9 R10 R11
		local readStr: byte,
			bytesRead: dword
		STACKALLOC 1

		lea RCX, continue
		call lstrlenA

		mov RCX, hStdOutput
		lea RDX, continue
		mov R8, RAX
		lea R9, bytesRead

		NULL_FIFTH_ARG
		call WriteConsoleA

		mov RCX, hStdInput
		lea RDX, readStr
		mov R8, 1
		lea R9, bytesRead
		NULL_FIFTH_ARG

		call ReadConsoleA

		STACKFREE
		ret
	inputAwaiting endp
end