MOVL	(index*4)(SI), AX; \
	BSWAPL	AX; \
	MOVL	AX, (index*4)(BP)

// Wt = SIGMA1(Wt-2) + Wt-7 + SIGMA0(Wt-15) + Wt-16; for 16 <= t <= 63
//   SIGMA0(x) = ROTR(7,x) XOR ROTR(18,x) XOR SHR(3,x)
//   SIGMA1(x) = ROTR(17,x) XOR ROTR(19,x) XOR SHR(10,x)
#define MSGSCHEDULE1(index) \
	MOVL	((index-2)*4)(BP), AX; \
	MOVL	AX, CX; \
	RORL	$17, AX; \
	MOVL	CX, DX; \
	RORL	$19, CX; \
	SHRL	$10, DX; \
	MOVL	((index-15)*4)(BP), BX; \

		// (-x) >> s == ^(x-1) >> s == ^((x-1) >> s) == -(((x-1) >> s) + 1)
		t := z.abs.sub(x.abs, natOne) // no underflow because |x| > 0
		t = t.shr(t, n)
		z.abs = t.add(t, natOne)
		z.neg = true // z cannot be zero if x is negative
		return z
	}

	z.abs = z.abs.shr(x.abs, n)
	z.neg = false
	return z
}

// Bit returns the value of the i'th bit of x. That is, it

			if s.ch == '-' {
				s.next()
				tok = token.ARROW
			} else {
				tok = s.switch4(token.LSS, token.LEQ, '<', token.SHL, token.SHL_ASSIGN)
			}
		case '>':
			tok = s.switch4(token.GTR, token.GEQ, '>', token.SHR, token.SHR_ASSIGN)
		case '=':
			tok = s.switch2(token.ASSIGN, token.EQL)
		case '!':
			tok = s.switch2(token.NOT, token.NEQ)
		case '&':
			if s.ch == '^' {
				s.next()

	{token.QUO, "/", operator},
	{token.REM, "%", operator},

	{token.AND, "&", operator},
	{token.OR, "|", operator},
	{token.XOR, "^", operator},
	{token.SHL, "<<", operator},
	{token.SHR, ">>", operator},
	{token.AND_NOT, "&^", operator},

	{token.ADD_ASSIGN, "+=", operator},
	{token.SUB_ASSIGN, "-=", operator},
	{token.MUL_ASSIGN, "*=", operator},
	{token.QUO_ASSIGN, "/=", operator},

		x.expr = e
		check.overflow(x, x.Pos())
		return
	}

	x.mode = value
	// x.typ remains unchanged
}

func isShift(op token.Token) bool {
	return op == token.SHL || op == token.SHR
}

func isComparison(op token.Token) bool {
	// Note: tokens are not ordered well to make this much easier
	switch op {
	case token.EQL, token.NEQ, token.LSS, token.LEQ, token.GTR, token.GEQ:
		return true

			z = new(Int)
		}
		z.neg = x.neg
		switch {
		case exp > allBits:
			z.abs = z.abs.shl(x.mant, exp-allBits)
		default:
			z.abs = z.abs.set(x.mant)
		case exp < allBits:
			z.abs = z.abs.shr(x.mant, allBits-exp)
		}
		return z, acc

	case zero:
		return z.SetInt64(0), Exact

	case inf:
		return nil, makeAcc(x.neg)
	}

	panic("unreachable")
}

		{name: "TESTBconst", argLength: 1, reg: gp1flags, asm: "TESTB", typ: "Flags", aux: "Int8"},

		// S{HL, HR, AR}x: shift operations
		// SHL: shift left
		// SHR: shift right logical (0s are shifted in from beyond the word size)
		// SAR: shift right arithmetic (sign bit is shifted in from beyond the word size)
		// arg0 is the value being shifted

		{"REM_ASSIGN", Const, 0},
		{"RETURN", Const, 0},
		{"RPAREN", Const, 0},
		{"SELECT", Const, 0},
		{"SEMICOLON", Const, 0},
		{"SHL", Const, 0},
		{"SHL_ASSIGN", Const, 0},
		{"SHR", Const, 0},
		{"SHR_ASSIGN", Const, 0},
		{"STRING", Const, 0},
		{"STRUCT", Const, 0},
		{"SUB", Const, 0},
		{"SUB_ASSIGN", Const, 0},
		{"SWITCH", Const, 0},
		{"TILDE", Const, 18},

pkg go/token, const RPAREN Token
pkg go/token, const SELECT Token
pkg go/token, const SEMICOLON Token
pkg go/token, const SHL Token
pkg go/token, const SHL_ASSIGN Token
pkg go/token, const SHR Token
pkg go/token, const SHR_ASSIGN Token
pkg go/token, const STRING Token
pkg go/token, const STRUCT Token
pkg go/token, const SUB Token
pkg go/token, const SUB_ASSIGN Token
pkg go/token, const SWITCH Token

pkg go/token, const RETURN = 80
pkg go/token, const RPAREN = 54
pkg go/token, const SELECT = 81
pkg go/token, const SEMICOLON = 57
pkg go/token, const SHL = 20
pkg go/token, const SHL_ASSIGN = 31
pkg go/token, const SHR = 21
pkg go/token, const SHR_ASSIGN = 32
pkg go/token, const STRING = 9
pkg go/token, const STRUCT = 82
pkg go/token, const SUB = 13
pkg go/token, const SUB_ASSIGN = 24
pkg go/token, const SWITCH = 83