// number = int_lit [ "p" int_lit ] .
//
func (p *gcParser) parseNumber() Const {
// mantissa
sign, val := p.parseInt()
mant, ok := new(big.Int).SetString(sign+val, 10)
assert(ok)
if p.lit == "p" {
// exponent (base 2)
p.next()
sign, val = p.parseInt()
exp, err := strconv.Atoui(val)
if err != nil {
p.error(err)
}
if sign == "-" {
denom := big.NewInt(1)
denom.Lsh(denom, exp)
return Const{new(big.Rat).SetFrac(mant, denom)}
}
if exp > 0 {
mant.Lsh(mant, exp)
}
return Const{new(big.Rat).SetInt(mant)}
}
return Const{mant}
}
func bitwise_arithmetic_shift_left(x, y Obj) Obj {
xfx := (uintptr(unsafe.Pointer(x)) & fixnum_mask) == fixnum_tag
yfx := (uintptr(unsafe.Pointer(y)) & fixnum_mask) == fixnum_tag
if !yfx {
panic("bad shift amount")
}
amount := uint(uintptr(unsafe.Pointer(y)) >> fixnum_shift)
if xfx && amount < 32-fixnum_shift {
i := int64(int(uintptr(unsafe.Pointer(x)) >> fixnum_shift))
r := i << amount
if r >= int64(fixnum_min) && r <= int64(fixnum_max) {
return Obj(unsafe.Pointer(uintptr((r << fixnum_shift) | fixnum_tag)))
} else {
return wrap(big.NewInt(r))
}
} else if xfx {
x = wrap(big.NewInt(int64(fixnum_to_int(x))))
} else if (uintptr(unsafe.Pointer(x)) & heap_mask) != heap_tag {
panic("bad type")
}
switch vx := (*x).(type) {
case *big.Int:
var z *big.Int = big.NewInt(0)
return wrap(z.Lsh(vx, amount))
}
panic("bad type")
}
// doubleJacobian takes a point in Jacobian coordinates, (x, y, z), and
// returns its double, also in Jacobian form.
func (curve *Curve) doubleJacobian(x, y, z *big.Int) (*big.Int, *big.Int, *big.Int) {
// See http://hyperelliptic.org/EFD/g1p/auto-shortw-jacobian-3.html#doubling-dbl-2001-b
delta := new(big.Int).Mul(z, z)
delta.Mod(delta, curve.P)
gamma := new(big.Int).Mul(y, y)
gamma.Mod(gamma, curve.P)
alpha := new(big.Int).Sub(x, delta)
if alpha.Sign() == -1 {
alpha.Add(alpha, curve.P)
}
alpha2 := new(big.Int).Add(x, delta)
alpha.Mul(alpha, alpha2)
alpha2.Set(alpha)
alpha.Lsh(alpha, 1)
alpha.Add(alpha, alpha2)
beta := alpha2.Mul(x, gamma)
x3 := new(big.Int).Mul(alpha, alpha)
beta8 := new(big.Int).Lsh(beta, 3)
x3.Sub(x3, beta8)
for x3.Sign() == -1 {
x3.Add(x3, curve.P)
}
x3.Mod(x3, curve.P)
z3 := new(big.Int).Add(y, z)
z3.Mul(z3, z3)
z3.Sub(z3, gamma)
if z3.Sign() == -1 {
z3.Add(z3, curve.P)
}
z3.Sub(z3, delta)
if z3.Sign() == -1 {
z3.Add(z3, curve.P)
}
z3.Mod(z3, curve.P)
beta.Lsh(beta, 2)
beta.Sub(beta, x3)
if beta.Sign() == -1 {
beta.Add(beta, curve.P)
}
y3 := alpha.Mul(alpha, beta)
gamma.Mul(gamma, gamma)
gamma.Lsh(gamma, 3)
gamma.Mod(gamma, curve.P)
y3.Sub(y3, gamma)
if y3.Sign() == -1 {
y3.Add(y3, curve.P)
}
y3.Mod(y3, curve.P)
return x3, y3, z3
}
// addJacobian takes two points in Jacobian coordinates, (x1, y1, z1) and
// (x2, y2, z2) and returns their sum, also in Jacobian form.
func (curve *Curve) addJacobian(x1, y1, z1, x2, y2, z2 *big.Int) (*big.Int, *big.Int, *big.Int) {
// See http://hyperelliptic.org/EFD/g1p/auto-shortw-jacobian-3.html#addition-add-2007-bl
z1z1 := new(big.Int).Mul(z1, z1)
z1z1.Mod(z1z1, curve.P)
z2z2 := new(big.Int).Mul(z2, z2)
z2z2.Mod(z2z2, curve.P)
u1 := new(big.Int).Mul(x1, z2z2)
u1.Mod(u1, curve.P)
u2 := new(big.Int).Mul(x2, z1z1)
u2.Mod(u2, curve.P)
h := new(big.Int).Sub(u2, u1)
if h.Sign() == -1 {
h.Add(h, curve.P)
}
i := new(big.Int).Lsh(h, 1)
i.Mul(i, i)
j := new(big.Int).Mul(h, i)
s1 := new(big.Int).Mul(y1, z2)
s1.Mul(s1, z2z2)
s1.Mod(s1, curve.P)
s2 := new(big.Int).Mul(y2, z1)
s2.Mul(s2, z1z1)
s2.Mod(s2, curve.P)
r := new(big.Int).Sub(s2, s1)
if r.Sign() == -1 {
r.Add(r, curve.P)
}
r.Lsh(r, 1)
v := new(big.Int).Mul(u1, i)
x3 := new(big.Int).Set(r)
x3.Mul(x3, x3)
x3.Sub(x3, j)
x3.Sub(x3, v)
x3.Sub(x3, v)
x3.Mod(x3, curve.P)
y3 := new(big.Int).Set(r)
v.Sub(v, x3)
y3.Mul(y3, v)
s1.Mul(s1, j)
s1.Lsh(s1, 1)
y3.Sub(y3, s1)
y3.Mod(y3, curve.P)
z3 := new(big.Int).Add(z1, z2)
z3.Mul(z3, z3)
z3.Sub(z3, z1z1)
if z3.Sign() == -1 {
z3.Add(z3, curve.P)
}
z3.Sub(z3, z2z2)
if z3.Sign() == -1 {
z3.Add(z3, curve.P)
}
z3.Mul(z3, h)
z3.Mod(z3, curve.P)
return x3, y3, z3
}
