// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build ignore

// Parses syscalls.abigen of Fuchsia's zircon kernel and produces Go assembly
// for calling the system calls.
//
// Regenerate syscall/zx with:
//
//	go run mkfuchsia.go -stubs > syscalls_fuchsia.go
//	go run mkfuchsia.go -goarch=amd64 > syscalls_fuchsia_amd64.s
//	go run mkfuchsia.go -goarch=arm64 > syscalls_fuchsia_arm64.s
//	gofmt -w syscalls_fuchsia.go
package main

import (
	"bytes"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"

	"internal/fuchsia/abigen"
)

var (
	stubs       = flag.Bool("stubs", false, "print only Go function stubs")
	goarch      = flag.String("goarch", "amd64", "arch to print asm for")
	fuchsiaRoot = flag.String("fuchsia_root", filepath.Join(os.Getenv("HOME"), "fuchsia"), "path to fuchsia root")
)

func main() {
	flag.Parse()
	sdkArch := ""
	switch *goarch {
	case "amd64":
		sdkArch = "x86_64"
	case "arm64":
		sdkArch = "aarch64"
	default:
		log.Fatalf("GOARCH=%s not supported", *goarch)
	}
	_ = sdkArch

	syscallsFile := filepath.Join(*fuchsiaRoot, "/zircon/system/public/zircon/syscalls.abigen")
	if args := flag.Args(); len(args) != 0 {
		syscallsFile = args[0]
	}

	b, err := ioutil.ReadFile(syscallsFile)
	if err != nil {
		log.Fatal(err)
	}

	p := abigen.NewParser(b, syscallsFile)
	defs, err := p.Parse()
	if err != nil {
		log.Fatal(err)
	}

	buf := new(bytes.Buffer)
	if *stubs {
		fmt.Fprint(buf, stubsHeader[1:])
		for _, def := range defs {
			fmt.Fprint(buf, "//go:noescape\n")
			fmt.Fprint(buf, "//go:nosplit\n")
			printStub(buf, def)
			fmt.Fprint(buf, "\n")
		}
	} else {
		fmt.Fprint(buf, asmHeader[1:])
		for _, def := range defs {
			fmt.Fprint(buf, "// ")
			printStub(buf, def)
			printAsm(buf, def)
			fmt.Fprint(buf, "\n")
		}
	}
	buf.WriteTo(os.Stdout)
}

const stubsHeader = `
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Zircon system calls for the Fuchsia OS.
// Generated by mkfuchsia.go, do not edit.

package zx

import "unsafe"

`

const asmHeader = `
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Zircon system calls for the Fuchsia OS.
// Generated by mkfuchsia.go, do not edit.

#include "textflag.h"
`

func printStub(buf *bytes.Buffer, def abigen.SysDef) {
	fmt.Fprintf(buf, "func %s(", def.GoName())
	for i, arg := range def.Args {
		if arg.Type == (abigen.SysType{}) {
			continue
		}
		if i > 0 {
			fmt.Fprint(buf, ", ")
		}
		fmt.Fprintf(buf, "%s ", arg.Name)
		fmt.Fprintf(buf, "%s", arg.Type.GoType())
	}
	fmt.Fprint(buf, ")")
	if def.Ret != (abigen.SysType{}) {
		fmt.Fprint(buf, " ")
		fmt.Fprintf(buf, "%s", def.Ret.GoType())
	}
	fmt.Fprint(buf, "\n")
}

func printAsm(buf *bytes.Buffer, def abigen.SysDef) {
	fmt.Fprintf(buf, "TEXT ·%s(SB),NOSPLIT,$0\n", def.GoName())
	fmt.Fprintf(buf, "\tJMP runtime·vdsoCall_zx_%s(SB)\n", def.Name)
}