package core

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

// CompileCall executes a function call.
// All call registers must hold the correct parameter values before the function invocation.
// Registers that are in use must be saved if they are modified by the function.
// After the function call, they must be restored in reverse order.
func (f *Function) CompileCall(expr *expression.Expression) error {
	_, err := f.EvaluateCall(expr)
	return err
}

// CompileSyscall executes a syscall.
func (f *Function) CompileSyscall(expr *expression.Expression) error {
	parameters := expr.Children[1:]
	registers := f.cpu.Syscall[:len(parameters)]
	err := f.ExpressionsToRegisters(parameters, registers)
	f.assembler.Syscall()
	f.sideEffects++
	return err
}

// ExpressionsToRegisters moves multiple expressions into the specified registers.
func (f *Function) ExpressionsToRegisters(expressions []*expression.Expression, registers []cpu.Register) error {
	for i := len(registers) - 1; i >= 0; i-- {
		f.SaveRegister(registers[i])
		err := f.EvaluateTo(expressions[i], registers[i])

		if err != nil {
			return err
		}
	}

	return nil
}