package build

import (
	"git.akyoto.dev/cli/q/src/build/arch/x64"
	"git.akyoto.dev/cli/q/src/build/asm"
	"git.akyoto.dev/cli/q/src/build/os/linux"
)

// Finalize generates the final machine code.
func Finalize(functions map[string]*Function) ([]byte, []byte) {
	a := entry()

	main := functions["main"]
	delete(functions, "main")
	a.Merge(&main.Assembler)

	for _, f := range functions {
		a.Merge(&f.Assembler)
	}

	code, data := a.Finalize()
	return code, data
}

// entry returns the entry point of the executable.
// The only job of the entry function is to call `main` and exit cleanly.
// The reason we call `main` instead of using `main` itself is to place
// a return address on the stack, which allows return statements in `main`.
func entry() *asm.Assembler {
	entry := asm.New()
	entry.Call("main")
	entry.RegisterNumber(asm.MOVE, x64.SyscallRegisters[0], linux.Exit)
	entry.RegisterNumber(asm.MOVE, x64.SyscallRegisters[1], 0)
	entry.Syscall()
	return entry
}