// Copyright 2015 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.

// This file encapsulates some of the odd characteristics of the
// 64-bit PowerPC (PPC64) instruction set, to minimize its interaction
// with the core of the assembler.

package arch

import (
	"cmd/internal/obj"
	"cmd/internal/obj/ppc64"
)

func jumpPPC64(word string) bool {

	MOVB	$-1, n-8(SP)          // 92fff010
	MOVB	$255, 4096(R4)        // ebff40000152
	MOVB	$-128, -524288(R5)    // eb8050008052
	MOVB	$1, -524289(R6)       // c0a1fff7ffff41aa60009201a000

	// RX (12-bit displacement) and RXY (20-bit displacement) instruction encoding (e.g: ST vs STY)
	MOVW	R1, 4095(R2)(R3)       // 50132fff
	MOVW	R1, 4096(R2)(R3)       // e31320000150
	MOVWZ	R1, 4095(R2)(R3)       // 50132fff

)

// uint8 is the set of all unsigned 8-bit integers.
// Range: 0 through 255.
type uint8 uint8

// uint16 is the set of all unsigned 16-bit integers.
// Range: 0 through 65535.
type uint16 uint16

// uint32 is the set of all unsigned 32-bit integers.
// Range: 0 through 4294967295.
type uint32 uint32

// uint64 is the set of all unsigned 64-bit integers.
// Range: 0 through 18446744073709551615.

not <code>3&amp;(1&lt;&lt;2)</code>.
Also, constants are always evaluated as 64-bit unsigned integers.
Thus <code>-2</code> is not the integer value minus two,
but the unsigned 64-bit integer with the same bit pattern.
The distinction rarely matters but
to avoid ambiguity, division or right shift where the right operand's
high bit is set is rejected.
</p>

<h3 id="symbols">Symbols</h3>

<p>

	{"3/0", "division by zero"},
	{"(1<<63)/0", "divide of value with high bit set"},
	{"3%0", "modulo by zero"},
	{"(1<<63)%0", "modulo of value with high bit set"},
	{"3<<-4", "negative left shift count"},
	{"3<<(1<<63)", "negative left shift count"},
	{"3>>-4", "negative right shift count"},
	{"3>>(1<<63)", "negative right shift count"},
	{"(1<<63)>>2", "right shift of value with high bit set"},
	{"(1<<62)>>2", ""},

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
the ZIP64 format the 32 bit fields will be 0xffffffff and the 64 bit
fields must be used instead.

[ZIP specification]: https://support.pkware.com/pkzip/appnote
*/
package zip

//
// If operating in binary mode, this assumes strict GNU binary mode; which means
// that the first byte can only be either 0x80 or 0xff. Thus, the first byte is
// equivalent to the sign bit in two's complement form.
func fitsInBase256(n int, x int64) bool {
	binBits := uint(n-1) * 8
	return n >= 9 || (x >= -1<<binBits && x < 1<<binBits)
}

<pre class="grammar">
uint8       the set of all unsigned  8-bit integers (0 to 255)
uint16      the set of all unsigned 16-bit integers (0 to 65535)
uint32      the set of all unsigned 32-bit integers (0 to 4294967295)
uint64      the set of all unsigned 64-bit integers (0 to 18446744073709551615)

int8        the set of all signed  8-bit integers (-128 to 127)
int16       the set of all signed 16-bit integers (-32768 to 32767)

The [RuneLen] function returns the number of 16-bit words in
the UTF-16 encoding of the rune. It returns -1 if the rune

	case arm.ASTREX, arm.ASTREXD, arm.ASWPW, arm.ASWPBU:
		return true
	}
	return false
}

// MCR is not defined by the obj/arm; instead we define it privately here.
// It is encoded as an MRC with a bit inside the instruction word,
// passed to arch.ARMMRCOffset.
const aMCR = arm.ALAST + 1

// IsARMMRC reports whether the op (as defined by an arm.A* constant) is
// MRC or MCR.
func IsARMMRC(op obj.As) bool {