}

// The read and write file descriptors used by the sigNote functions.
var sigNoteRead, sigNoteWrite int32

// sigNoteSetup initializes a single, there-can-only-be-one, async-signal-safe note.
//
// The current implementation of notes on Darwin is not async-signal-safe,
// because the functions pthread_mutex_lock, pthread_cond_signal, and
// pthread_mutex_unlock, called by semawakeup, are not async-signal-safe.

	if d == nil {
		d = new(dirInfo)
		f.dirinfo.Store(d)
	}
	d.mu.Lock()
	defer d.mu.Unlock()
	if d.buf == nil {
		d.buf = dirBufPool.Get().(*[]byte)
	}

	// Change the meaning of n for the implementation below.
	//
	// The n above was for the public interface of "if n <= 0,
	// Readdir returns all the FileInfo from the directory in a
	// single slice".
	//
	// But below, we use only negative to mean looping until the

				golden := makeGolden(dst, b, src, src.Bounds().Min, nil, image.Point{}, op)
				if !b.Eq(golden.Bounds()) {
					t.Errorf("drawOverlap xoff=%d,yoff=%d: bounds %v versus %v", xoff, yoff, dst.Bounds(), golden.Bounds())
					continue
				}
				// Draw the same combination onto the actual dst using the optimized DrawMask implementation.

			}
			i += keylen
			last = i
			continue
		}
		i++
	}
	if last != len(s) {
		wn, err = sw.WriteString(s[last:])
		n += wn
	}
	return
}

// singleStringReplacer is the implementation that's used when there is only
// one string to replace (and that string has more than one byte).
type singleStringReplacer struct {
	finder *stringFinder

// Copyright 2017 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 semaphore provides a weighted semaphore implementation.
package semaphore // import "golang.org/x/sync/semaphore"

import (
	"container/list"
	"context"
	"sync"
)

type waiter struct {
	n     int64
	ready chan<- struct{} // Closed when semaphore acquired.
}

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package zlib implements reading and writing of zlib format compressed data,
as specified in RFC 1950.

The implementation provides filters that uncompress during reading
and compress during writing.  For example, to write compressed data
to a buffer:

	var b bytes.Buffer
	w := zlib.NewWriter(&b)
	w.Write([]byte("hello, world\n"))

}

func xattrPointer(dest []byte) *byte {
	// It's only when dest is set to NULL that the OS X implementations of
	// getxattr() and listxattr() return the current sizes of the named attributes.
	// An empty byte array is not sufficient. To maintain the same behaviour as the
	// linux implementation, we wrap around the system calls and pass in NULL when
	// dest is empty.
	var destp *byte
	if len(dest) > 0 {

func (conf *Config) alignof(T Type) int64 {
	f := stdSizes.Alignof
	if conf.Sizes != nil {
		f = conf.Sizes.Alignof
	}
	if a := f(T); a >= 1 {
		return a
	}
	panic("implementation of alignof returned an alignment < 1")
}

func (conf *Config) offsetsof(T *Struct) []int64 {
	var offsets []int64
	if T.NumFields() > 0 {
		// compute offsets on demand
		f := stdSizes.Offsetsof

// but it is also input to mksyscall,
// which parses the //sys lines and generates system call stubs.
// Note that sometimes we use a lowercase //sys name and wrap
// it in our own nicer implementation, either here or in
// syscall_bsd.go or syscall_unix.go.

package syscall

import "unsafe"

func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)

// TypeList instead.
func (l *TypeList) list() []Type {
	if l == nil {
		return nil
	}
	return l.types
}

// ----------------------------------------------------------------------------
// Implementation

func bindTParams(list []*TypeParam) *TypeParamList {
	if len(list) == 0 {
		return nil
	}
	for i, typ := range list {
		if typ.index >= 0 {
			panic("type parameter bound more than once")
		}