package x64

import "git.akyoto.dev/cli/q/src/build/cpu"

// MoveRegNum32 moves a 32 bit integer into the given register.
func MoveRegNum32(code []byte, destination cpu.Register, number uint32) []byte {
	if destination >= 8 {
		code = append(code, REX(0, 0, 0, 1))
		destination -= 8
	}

	return append(
		code,
		0xb8+byte(destination),
		byte(number),
		byte(number>>8),
		byte(number>>16),
		byte(number>>24),
	)
}

// MoveRegReg64 moves a register value into another register.
func MoveRegReg64(code []byte, destination cpu.Register, source cpu.Register) []byte {
	r := byte(0) // Extension to the "reg" field in ModRM.
	b := byte(0) // Extension to the "rm" field in ModRM or the SIB base (r8 up to r15 use this).

	if source >= 8 {
		r = 1
		source -= 8
	}

	if destination >= 8 {
		b = 1
		destination -= 8
	}

	return append(
		code,
		REX(1, r, 0, b),
		0x89,
		ModRM(0b11, byte(source), byte(destination)),
	)
}