package x86

import (
	"encoding/binary"

	"git.urbach.dev/cli/q/src/cpu"
)

// memLoadExtend encodes a memory load with sign or zero extension.
func memLoadExtend(code []byte, register cpu.Register, base cpu.Register, offset int32, length byte, opCode8 uint32, opCode16 uint32, opCode32 uint32) []byte {
	var (
		opCode uint32
		mod    = AddressMemory
	)

	switch length {
	case 1:
		opCode = opCode8
	case 2:
		opCode = opCode16
	case 4:
		opCode = opCode32
	}

	if offset != 0 || base == R5 || base == R13 {
		mod = AddressMemoryOffset8

		if cpu.SizeInt(int64(offset)) > 1 {
			mod = AddressMemoryOffset32
		}
	}

	code = encode(code, mod, register, base, 8, opCode)

	switch mod {
	case AddressMemoryOffset8:
		return append(code, byte(offset))
	case AddressMemoryOffset32:
		return binary.LittleEndian.AppendUint32(code, uint32(offset))
	default:
		return code
	}
}