// It then attempts to guess the specific format based on magic values.
// If the checksum fails, then FormatUnknown is returned.
func (b *block) getFormat() Format {
	// Verify checksum.
	var p parser
	value := p.parseOctal(b.toV7().chksum())
	chksum1, chksum2 := b.computeChecksum()
	if p.err != nil || (value != chksum1 && value != chksum2) {
		return FormatUnknown
	}

	// Guess the magic values.

	return tok
}

func (p *Parser) back() {
	if p.inputPos == 0 {
		p.errorf("internal error: backing up before BOL")
	} else {
		p.inputPos--
	}
}

func (p *Parser) peek() lex.ScanToken {
	if p.more() {
		return p.input[p.inputPos].ScanToken
	}
	return scanner.EOF
}

func (p *Parser) more() bool {
	return p.inputPos < len(p.input)
}

	}
}

func TestAMD64OperandParser(t *testing.T) {
	parser := newParser("amd64")
	testOperandParser(t, parser, amd64OperandTests)
	testBadOperandParser(t, parser, amd64BadOperandTests)
	parser.allowABI = true
	testOperandParser(t, parser, amd64RuntimeOperandTests)
	testBadOperandParser(t, parser, amd64BadOperandRuntimeTests)
}

func Test386OperandParser(t *testing.T) {
	parser := newParser("386")

// Parse input AST and prepare Prog structure.

package main

import (
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/scanner"
	"go/token"
	"os"
	"strings"
)

func parse(name string, src []byte, flags parser.Mode) *ast.File {
	ast1, err := parser.ParseFile(fset, name, src, flags)
	if err != nil {
		if list, ok := err.(scanner.ErrorList); ok {

		{"0123456789abcdef", 0, false},
		{"0123456789\x00abcdef", 0, false},
		{"01234567\x0089abcdef", 342391, true},
		{"0123\x7e\x5f\x264123", 0, false},
	}

	for _, v := range vectors {
		var p parser
		got := p.parseNumeric([]byte(v.in))
		ok := (p.err == nil)
		if ok != v.ok {
			if v.ok {
				t.Errorf("parseNumeric(%q): got parsing failure, want success", v.in)
			} else {

decide which.

The obvious thing for cgo to do is to process the preamble, expanding
#includes and processing the corresponding C code. That would require
a full C parser and type checker that was also aware of any extensions
known to the system compiler (for example, all the GNU C extensions) as
well as the system-specific header locations and system-specific

// converted to int they correspond to the rune size that was read.
type readOp int8

// Don't use iota for these, as the values need to correspond with the
// names and comments, which is easier to see when being explicit.
const (
	opRead      readOp = -1 // Any other read operation.
	opInvalid   readOp = 0  // Non-read operation.
	opReadRune1 readOp = 1  // Read rune of size 1.

	}
	return true
}

// evalInteger evaluates an integer constant for a pseudo-op.
func (p *Parser) evalInteger(pseudo string, operands []lex.Token) int64 {
	addr := p.address(operands)
	return p.getConstantPseudo(pseudo, &addr)
}

// validImmediate checks that addr represents an immediate constant.
func (p *Parser) validImmediate(pseudo string, addr *obj.Addr) bool {

	architecture, ctxt := setArch(goarch)
	architecture.Init(ctxt)
	lexer := lex.NewLexer(input)
	parser := NewParser(ctxt, architecture, lexer)
	pList := new(obj.Plist)
	var ok bool
	ctxt.Bso = bufio.NewWriter(os.Stdout)
	ctxt.IsAsm = true
	defer ctxt.Bso.Flush()
	failed := false
	var errBuf bytes.Buffer
	parser.errorWriter = &errBuf
	ctxt.DiagFunc = func(format string, args ...interface{}) {
		failed = true

		case TypeGNULongName, TypeGNULongLink:
			format.mayOnlyBe(FormatGNU)
			realname, err := readSpecialFile(tr)
			if err != nil {
				return nil, err
			}

			var p parser
			switch hdr.Typeflag {
			case TypeGNULongName:
				gnuLongName = p.parseString(realname)
			case TypeGNULongLink:
				gnuLongLink = p.parseString(realname)
			}