// Copyright 2011 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.

package runtime

import (
	"unsafe"
)

type mOS struct{}

//go:noescape
//extern _umtx_op
func sys_umtx_op(addr *uint32, mode int32, val uint32, uaddr1 uinptr, ts *umtx_time) int32

func getPageSize() uintptr {
	mib := [2]uint32{_CTL_HW, _HW_PAGESIZE}
	out := uint32(0)
	nout := unsafe.Sizeof(out)
	ret := sysctl(&mib[0], 2, (*byte)(unsafe.Pointer(&out)), &nout, nil, 0)
	if ret >= 0 {
		return uintptr(out)
	}
	return 0
}

// FreeBSD's umtx_op syscall is effectively the same as Linux's futex, and
// thus the code is largely similar. See Linux implementation
// and lock_futex.go for comments.

//go:nosplit
func futexsleep(addr *uint32, val uint32, ns int64) {
	systemstack(func() {
		futexsleep1(addr, val, ns)
	})
}

func futexsleep1(addr *uint32, val uint32, ns int64) {
	var utp *umtx_time
	if ns >= 0 {
		var ut umtx_time
		ut._clockid = _CLOCK_MONOTONIC
		ut._timeout.set_sec(int64(timediv(ns, 1000000000, (*int32)(unsafe.Pointer(&ut._timeout.tv_nsec)))))
		utp = &ut
	}
	ret := sys_umtx_op(addr, _UMTX_OP_WAIT_UINT_PRIVATE, val, unsafe.Sizeof(*utp), utp)
	if ret >= 0 || ret == -_EINTR {
		return
	}
	print("umtx_wait addr=", addr, " val=", val, " ret=", ret, "\n")
	*(*int32)(unsafe.Pointer(uintptr(0x1005))) = 0x1005
}

//go:nosplit
func futexwakeup(addr *uint32, cnt uint32) {
	ret := sys_umtx_op(addr, _UMTX_OP_WAKE_PRIVATE, cnt, 0, nil)
	if ret >= 0 {
		return
	}

	systemstack(func() {
		print("umtx_wake_addr=", addr, " ret=", ret, "\n")
	})
}

func sysargs(argc int32, argv **byte) {
	n := argc + 1

	// skip over argv, envp to get to auxv
	for argv_index(argv, n) != nil {
		n++
	}

	// skip NULL separator
	n++

	// now argv+n is auxv
	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
	sysauxv(auxv[:])
}

const (
	_AT_NULL     = 0  // Terminates the vector
	_AT_PAGESZ   = 6  // Page size in bytes
	_AT_TIMEKEEP = 22 // Pointer to timehands.
	_AT_HWCAP    = 25 // CPU feature flags
	_AT_HWCAP2   = 26 // CPU feature flags 2
)

func sysauxv(auxv []uintptr) {
	for i := 0; auxv[i] != _AT_NULL; i += 2 {
		tag, val := auxv[i], auxv[i+1]
		switch tag {
		// _AT_NCPUS from auxv shouldn't be used due to golang.org/issue/15206
		case _AT_PAGESZ:
			physPageSize = val
		case _AT_TIMEKEEP:
			timekeepSharedPage = (*vdsoTimekeep)(unsafe.Pointer(val))
		}

		archauxv(tag, val)
	}
}