"crypto/subtle"
)

// A dynamic lookup table for variable-base, constant-time scalar muls.
type projLookupTable struct {
	points [8]projCached
}

// A precomputed lookup table for fixed-base, constant-time scalar muls.
type affineLookupTable struct {
	points [8]affineCached
}

// A dynamic lookup table for variable-base, variable-time scalar muls.
type nafLookupTable5 struct {
	points [8]projCached
}

	"DIV",
	"MOD",
	"MODU",
	"DIVHW",
	"DIVUHW",
	"MOVB",
	"MOVBS",
	"MOVBU",
	"MOVH",
	"MOVHS",
	"MOVHU",
	"MOVW",
	"MOVM",
	"SWPBU",
	"SWPW",
	"RFE",
	"SWI",
	"MULA",
	"MULS",
	"MMULA",
	"MMULS",
	"WORD",
	"MULL",
	"MULAL",
	"MULLU",
	"MULALU",
	"BX",
	"BXRET",
	"DWORD",
	"LDREX",
	"STREX",
	"LDREXD",
	"STREXD",
	"DMB",
	"PLD",

	r2 := b*64 + c
	return r0, r1, r2
}

func MULS(a, b, c uint32) (uint32, uint32, uint32) {
	// arm/7:`MULS`,-`MUL\s`
	// arm/6:`SUB`,`MUL\s`,-`MULS`
	// arm64:`MSUBW`,-`MULW`
	r0 := c - a*b
	// arm/7:`MULS`,-`MUL\s`
	// arm/6:`SUB`,`MUL\s`,-`MULS`
	// arm64:`MSUBW`,-`MULW`
	r1 := a - c*79
	// arm/7:`SUB`,-`MULS`,-`MUL\s`
	// arm64:`SUB`,-`MSUBW`,-`MULW`
	// ppc64x:`SUB`,-`MULLD`

		4, 3, 3, 5, 9,
		6, 2, 5, 6, 5,
		4, 5, 5, 3, 10,
		2, 5, 5, 3, 7, 6}
	muls := []*p256OrdElement{
		_101111, _111, _11, _1111, _10101,
		_101, _101, _101, _111, _101111,
		_1111, _1, _1, _1111, _111,
		_111, _111, _101, _11, _101111,
		_11, _11, _11, _1, _10101, _1111}

	for i, s := range sqrs {
		p256OrdSqr(x, x, s)
		p256OrdMul(x, x, muls[i])
	}

	// Montgomery multiplication by R⁻¹, or 1 outside the domain as R⁻¹×R = 1,

(MULS x (MOVWconst [c]) a) && c == -1 => (ADD a x)
(MULS _ (MOVWconst [0]) a) => a
(MULS x (MOVWconst [1]) a) => (RSB x a)
(MULS x (MOVWconst [c]) a) && isPowerOfTwo32(c) => (RSB (SLLconst <x.Type> [int32(log32(c))] x) a)
(MULS x (MOVWconst [c]) a) && isPowerOfTwo32(c-1) && c >= 3 => (RSB (ADDshiftLL <x.Type> x x [int32(log32(c-1))]) a)

	MOVD	0x00ffffff(F2), F1 // ERROR "illegal base register"
	MOVF	F2, 0x00ffffff(F2) // ERROR "illegal base register"
	MOVD	F2, 0x00ffffff(F2) // ERROR "illegal base register"
	MULS.S	R1, R2, R3, R4     // ERROR "invalid .S suffix"
	ADD.P	R1, R2, R3         // ERROR "invalid .P suffix"
	SUB.W	R2, R3             // ERROR "invalid .W suffix"
	BL	4(R4)              // ERROR "non-zero offset"

		((x5 & 7) << 5) | // coprocessor information
		(1 << 4) /* must be set */
	return offset, arm.AMRC, true
}

// IsARMMULA reports whether the op (as defined by an arm.A* constant) is
// MULA, MULS, MMULA, MMULS, MULABB, MULAWB or MULAWT, the 4-operand instructions.
func IsARMMULA(op obj.As) bool {
	switch op {
	case arm.AMULA, arm.AMULS, arm.AMMULA, arm.AMMULS, arm.AMULABB, arm.AMULAWB, arm.AMULAWT:
		return true

	v_0 := v.Args[0]
	b := v.Block
	// match: (MULS x (MOVWconst [c]) a)
	// cond: c == -1
	// result: (ADD a x)
	for {
		x := v_0
		if v_1.Op != OpARMMOVWconst {
			break
		}
		c := auxIntToInt32(v_1.AuxInt)
		a := v_2
		if !(c == -1) {
			break
		}
		v.reset(OpARMADD)
		v.AddArg2(a, x)
		return true
	}
	// match: (MULS _ (MOVWconst [0]) a)
	// result: a
	for {

		{name: "MULA", argLength: 3, reg: gp31, asm: "MULA"},                      // arg0 * arg1 + arg2
		{name: "MULS", argLength: 3, reg: gp31, asm: "MULS"},                      // arg2 - arg0 * arg1

		{name: "ADDF", argLength: 2, reg: fp21, asm: "ADDF", commutative: true},   // arg0 + arg1

	MOVW	R0, R1<<0(R2)        // 010082e7
	MOVW	R0, R1>>0(R2)        // 010082e7
	MOVW	R0, R1->0(R2)        // 010082e7
	MOVW	R0, R1@>0(R2)        // 010082e7

// MULA / MULS
	MULAWT		R1, R2, R3, R4       // c23124e1
	MULAWB		R1, R2, R3, R4       // 823124e1
	MULS		R1, R2, R3, R4       // 923164e0
	MULA		R1, R2, R3, R4       // 923124e0
	MULA.S		R1, R2, R3, R4       // 923134e0
	MMULA		R1, R2, R3, R4       // 123154e7