together. The directive can include a list of build constraints limiting its
effect to systems satisfying one of the constraints
(see https://golang.org/pkg/go/build/#hdr-Build_Constraints for details about the constraint syntax).
For example:

	// #cgo CFLAGS: -DPNG_DEBUG=1
	// #cgo amd64 386 CFLAGS: -DX86=1
	// #cgo LDFLAGS: -lpng
	// #include <png.h>
	import "C"

// license that can be found in the LICENSE file.

/*
Package zip provides support for reading and writing ZIP archives.

See the [ZIP specification] for details.

This package does not support disk spanning.

A note about ZIP64:

To be backwards compatible the FileHeader has both 32 and 64 bit Size
fields. The 64 bit fields will always contain the correct value and
for normal archives both fields will be the same. For files requiring

	{"R5", "R5"},
	{"R6", "R6"},
	{"R7", "R7"},
	{"R8", "R8"},
	{"R9", "R9"},
	{"SPR(269)", "SPR(269)"},
	{"a(FP)", "a(FP)"},
	{"g", "g"},
	{"ret+8(FP)", "ret+8(FP)"},
	{"runtime·abort(SB)", "runtime.abort(SB)"},
	{"·AddUint32(SB)", "pkg.AddUint32(SB)"},
	{"·trunc(SB)", "pkg.trunc(SB)"},
	{"[):[o-FP", ""}, // Issue 12469 - asm hung parsing the o-FP range on non ARM platforms.
}

what is explained in that document, and
describes the peculiarities that apply when writing assembly code to interact with Go.
</p>

<p>
The most important thing to know about Go's assembler is that it is not a direct representation of the underlying machine.
Some of the details map precisely to the machine, but some do not.
This is because the compiler suite (see

// returns a slice of subslices of s. If all code points in s satisfy f(c), or
// len(s) == 0, an empty slice is returned.
//
// FieldsFunc makes no guarantees about the order in which it calls f(c)
// and assumes that f always returns the same value for a given c.
func FieldsFunc(s []byte, f func(rune) bool) [][]byte {
	// A span is used to record a slice of s of the form s[start:end].

func newExitCodeFilter(w io.Writer) (*exitCodeFilter, string) {
	const exitStr = "exitcode="

	// Build a regexp that matches any prefix of the exit string at the end of
	// the input. We do it this way to avoid assuming anything about the
	// subcommand output (e.g., it might not be \n-terminated).
	var exitReStr strings.Builder
	for i := 1; i <= len(exitStr); i++ {
		fmt.Fprintf(&exitReStr, "%s$|", exitStr[:i])
	}

		errorWriter: os.Stderr,
		allowABI:    ctxt != nil && objabi.LookupPkgSpecial(ctxt.Pkgpath).AllowAsmABI,
		pkgPrefix:   pkgPrefix,
	}
}

// panicOnError is enabled when testing to abort execution on the first error
// and turn it into a recoverable panic.
var panicOnError bool

func (p *Parser) errorf(format string, args ...interface{}) {
	if panicOnError {
		panic(fmt.Errorf(format, args...))
	}

// discard skips n bytes in r, reporting an error if unable to do so.
func discard(r io.Reader, n int64) error {
	// If possible, Seek to the last byte before the end of the data section.
	// Do this because Seek is often lazy about reporting errors; this will mask
	// the fact that the stream may be truncated. We can rely on the
	// io.CopyN done shortly afterwards to trigger any IO errors.
	var seekSkipped int64 // Number of bytes skipped via Seek

// allow the I/O-intensive phases of 'go list' to overlap) instead of scaling
// all the way up to GOMAXPROCS.
var listSem = make(chan semToken, 2)

type semToken struct{}

// loadImports populates w with information about the packages in the standard
// library and the packages they themselves import in w's build context.
//
// The source import path and expanded import path are identical except for vendored packages.
// For example, on return: