// including forms involving multiple registers such as R1:R2.
func (p *Parser) register(name string, prefix rune) (r1, r2 int16, scale int8, ok bool) {
	// R1 or R(1) R1:R2 R1,R2 R1+R2, or R1*scale.
	r1, ok = p.registerReference(name)
	if !ok {
		return
	}
	if prefix != 0 && prefix != '*' { // *AX is OK.
		p.errorf("prefix %c not allowed for register: %c%s", prefix, prefix, name)
	}
	c := p.peek()

	default:
		return n, nil
	}
}

func (sw *sparseFileWriter) ReadFrom(r io.Reader) (n int64, err error) {
	rs, ok := r.(io.ReadSeeker)
	if ok {
		if _, err := rs.Seek(0, io.SeekCurrent); err != nil {
			ok = false // Not all io.Seeker can really seek
		}
	}
	if !ok {
		return io.Copy(struct{ io.Writer }{sw}, r)
	}

	var readLastByte bool
	pos0 := sw.pos

	sys, ok := fi.Sys().(*syscall.Stat_t)
	if !ok {
		return nil
	}
	h.Uid = int(sys.Uid)
	h.Gid = int(sys.Gid)
	if doNameLookups {
		// Best effort at populating Uname and Gname.
		// The os/user functions may fail for any number of reasons
		// (not implemented on that platform, cgo not enabled, etc).
		if u, ok := userMap.Load(h.Uid); ok {
			h.Uname = u.(string)

	pList := new(obj.Plist)
	var ok bool
	testOut = new(strings.Builder) // The assembler writes test output to this buffer.
	ctxt.Bso = bufio.NewWriter(os.Stdout)
	ctxt.IsAsm = true
	defer ctxt.Bso.Flush()
	failed := false
	ctxt.DiagFunc = func(format string, args ...interface{}) {
		failed = true
		t.Errorf(format, args...)
	}
	pList.Firstpc, ok = parser.Parse()
	if !ok || failed {

		return nil
	}
	if cutset == "" {
		return s
	}
	if len(cutset) == 1 && cutset[0] < utf8.RuneSelf {
		return trimLeftByte(trimRightByte(s, cutset[0]), cutset[0])
	}
	if as, ok := makeASCIISet(cutset); ok {
		return trimLeftASCII(trimRightASCII(s, &as), &as)
	}
	return trimLeftUnicode(trimRightUnicode(s, cutset), cutset)
}

// TrimLeft returns a subslice of s by slicing off all leading

// from a closed channel c, any receive from c will succeed without
// blocking, returning the zero value for the channel element. The form
//
//	x, ok := <-c
//
// will also set ok to false for a closed and empty channel.
func close(c chan<- Type)

// The panic built-in function stops normal execution of the current

			// reports errors to parser.Errorf
			if ok {
				obj.Flushplist(ctxt, pList, nil)
			}
		}
		if !ok {
			failedFile = f
			break
		}
	}
	if ok && !*flags.SymABIs {
		ctxt.NumberSyms()
		obj.WriteObjFile(ctxt, buf)
	}
	if !ok || diag {
		if failedFile != "" {
			log.Printf("assembly of %s failed", failedFile)
		} else {
			log.Print("assembly failed")
		}

		t.Errorf("ModifiedTime: got %d, want %d\n", got, want)
	}
	if got, want := fh2.ModifiedDate, fh.ModifiedDate; got != want {
		t.Errorf("ModifiedDate: got %d, want %d\n", got, want)
	}

	if sysfh, ok := fi.Sys().(*FileHeader); !ok && sysfh != fh {
		t.Errorf("Sys didn't return original *FileHeader")
	}
}

func TestFileHeaderRoundTrip(t *testing.T) {
	fh := &FileHeader{
		Name:             "foo.txt",

	// .Z instructions
	VMOVDQA32.Z Z0, Z1               // ERROR "mask register must be specified for .Z instructions"
	VMOVDQA32.Z Z0, K0, Z1           // ERROR "invalid instruction"
	VMOVDQA32.Z Z0, K1, Z1           // ok

	RDPID (BX)			 // ERROR "invalid instruction"

	switch valueAddr.Type {
	case obj.TYPE_CONST, obj.TYPE_FCONST, obj.TYPE_SCONST, obj.TYPE_ADDR:
		// OK
	default:
		p.errorf("DATA value must be an immediate constant or address")
		return
	}

	// The addresses must not overlap. Easiest test: require monotonicity.
	if lastAddr, ok := p.dataAddr[name]; ok && nameAddr.Offset < lastAddr {
		p.errorf("overlapping DATA entry for %s", name)
		return
	}