{math.MinInt64, 9, true},
		{math.MaxInt64, 12, true},
		{0, 12, true},
		{math.MinInt64, 12, true},
	}

	for _, v := range vectors {
		ok := fitsInBase256(v.width, v.in)
		if ok != v.ok {
			t.Errorf("fitsInBase256(%d, %d): got %v, want %v", v.in, v.width, ok, v.ok)
		}
	}
}

func TestParseNumeric(t *testing.T) {
	vectors := []struct {
		in   string
		want int64
		ok   bool
	}{

		// While not recommended, it is valid to append to a shifted buffer.
		// This forces Write to copy the input.
		if rn.Intn(8) == 0 && cap(b) > 0 {
			b = b[1:1:cap(b)]
		}

		// Append a random integer of varying width.
		n := int64(rn.Intn(1 << rn.Intn(30)))
		want = append(strconv.AppendInt(want, n, 10), ' ')
		b = append(strconv.AppendInt(b, n, 10), ' ')
		w.Write(b)
	}
	w.Flush()

	if !bytes.Equal(got.Bytes(), want) {

<p>
For unsigned integer values, the operations <code>+</code>,
<code>-</code>, <code>*</code>, and <code>&lt;&lt;</code> are
computed modulo 2<sup><i>n</i></sup>, where <i>n</i> is the bit width of
the <a href="#Numeric_types">unsigned integer</a>'s type.
Loosely speaking, these unsigned integer operations
discard high bits upon overflow, and programs may rely on "wrap around".
</p>
<p>

<!--
NOTE: In this document and others in this directory, the convention is to
set fixed-width phrases with non-fixed-width spaces, as in
`hello` `world`.
-->

<style>
  main ul li { margin: 0.5em 0; }
</style>

	// Skip leading spaces.
	start := 0
	for width := 0; start < len(data); start += width {
		var r rune
		r, width = utf8.DecodeRune(data[start:])
		if !isSpace(r) {
			break
		}
	}
	// Scan until space, marking end of word.
	for width, i := 0, start; i < len(data); i += width {
		var r rune
		r, width = utf8.DecodeRune(data[i:])
		if isSpace(r) {
			return i + width, data[start:i], nil
		}
	}

<!--
NOTE: In this document and others in this directory, the convention is to
set fixed-width phrases with non-fixed-width spaces, as in
`hello` `world`.
-->

<style>
  main ul li { margin: 0.5em 0; }
</style>

				}
			}
			return -1
		}
	}
	var width int
	for i := 0; i < len(s); i += width {
		r := rune(s[i])
		if r < utf8.RuneSelf {
			if bytealg.IndexByteString(chars, s[i]) >= 0 {
				return i
			}
			width = 1
			continue
		}
		r, width = utf8.DecodeRune(s[i:])
		if r != utf8.RuneError {
			// r is 2 to 4 bytes
			if len(chars) == width {
				if chars == string(r) {
					return i
				}

	MOVFW	R1, CPSR           // ERROR "illegal combination"
	BFX	$12, $41, R2, R3   // ERROR "wrong width or LSB"
	BFX	$12, $-2, R2       // ERROR "wrong width or LSB"
	BFXU	$40, $4, R2, R3    // ERROR "wrong width or LSB"
	BFXU	$-40, $4, R2       // ERROR "wrong width or LSB"
	BFX	$-2, $4, R2, R3    // ERROR "wrong width or LSB"
	BFXU	$4, R2, R5, R2     // ERROR "missing or wrong LSB"

		return true
	}
	return false
}

// IsARMBFX reports whether the op (as defined by an arm.A* constant) is one the
// BFX-like instructions which are in the form of "op $width, $LSB, (Reg,) Reg".
func IsARMBFX(op obj.As) bool {
	switch op {
	case arm.ABFX, arm.ABFXU, arm.ABFC, arm.ABFI:
		return true
	}
	return false
}

corresponding memory.
The memory not explicitly initialized is zeroed.
The general form of the <code>DATA</code> directive is

<pre>
DATA	symbol+offset(SB)/width, value
</pre>

<p>
which initializes the symbol memory at the given offset and width with the given value.
The <code>DATA</code> directives for a given symbol must be written with increasing offsets.
</p>

<p>