package core

import (
	"git.akyoto.dev/cli/q/src/build/expression"
)

// CompileSyscall executes a kernel syscall.
func (f *Function) CompileSyscall(root *expression.Expression) error {
	parameters := root.Children[1:]
	registers := f.CPU.SyscallInput[:len(parameters)]
	err := f.ExpressionsToRegisters(parameters, registers)

	if err != nil {
		return err
	}

	for _, register := range f.CPU.SyscallOutput {
		f.SaveRegister(register)
	}

	f.Syscall()

	for _, register := range registers {
		if register == f.CPU.SyscallOutput[0] && root.Parent != nil {
			continue
		}

		f.FreeRegister(register)
	}

	return nil
}