Exemplo n.º 1
0
// SetBytes interprets b as the bytes of a big-endian integer
// and sets z to that value.
func (z *Int) SetBytes(b []byte) *Int {
	z.doinit()
	if len(b) == 0 {
		z.SetInt64(0)
	} else {
		C.mpz_import(&z.i[0], C.size_t(len(b)), 1, 1, 1, 0, unsafe.Pointer(&b[0]))
	}
	return z
}
Exemplo n.º 2
0
Arquivo: int.go Projeto: locusf/gmp
// SetUint64 sets z to x and returns z.
func (z *Int) SetUint64(x uint64) *Int {
	z.doinit()
	// Test for truncation
	y := C.ulong(x)
	if uint64(y) == x {
		C.mpz_set_ui(&z.i[0], y)
	} else {
		C.mpz_import(&z.i[0], 1, 0, 8, 0, 0, unsafe.Pointer(&x))
	}
	return z
}
Exemplo n.º 3
0
Arquivo: int.go Projeto: locusf/gmp
// SetInt64 sets z to x and returns z.
func (z *Int) SetInt64(x int64) *Int {
	z.doinit()
	// Test for truncation
	y := C.long(x)
	if int64(y) == x {
		C.mpz_set_si(&z.i[0], y)
	} else {
		negative := false
		if x < 0 {
			x = -x
			negative = true
		}
		C.mpz_import(&z.i[0], 1, 0, 8, 0, 0, unsafe.Pointer(&x))
		if negative {
			C.mpz_neg(&z.i[0], &z.i[0])
		}
	}
	return z
}
Exemplo n.º 4
0
Arquivo: int.go Projeto: locusf/gmp
// Rand sets z to a pseudo-random number in [0, n) and returns z.
func (z *Int) Rand(rnd *rand.Rand, n *Int) *Int {
	z.doinit()
	// Get rid of n <= 0 case
	if n.Sign() <= 0 {
		z.SetInt64(0)
		return z
	}
	// Make a copy of n if aliased
	t := n
	aliased := false
	if n == z {
		aliased = true
		t = new(Int).Set(n)
	}
	// Work out bit sizes and masks
	bits := n.BitLen()         // >= 1
	nwords := (bits + 31) / 32 // >= 1
	bitLengthOfMSW := uint(bits % 32)
	if bitLengthOfMSW == 0 {
		bitLengthOfMSW = 32
	}
	mask := uint32((1 << bitLengthOfMSW) - 1)
	words := make([]uint32, nwords)
	for {
		// Make a most significant first array of random bytes
		for i := 0; i < nwords; i++ {
			words[i] = rnd.Uint32()
		}
		// Mask out the top bits so this is only just bigger than n
		words[0] &= mask
		C.mpz_import(&z.i[0], C.size_t(len(words)), 1, 4, 0, 0, unsafe.Pointer(&words[0]))
		// Exit if z < n - should take ~1.5 iterations of loop on average
		if z.Cmp(t) < 0 {
			break
		}
	}
	if aliased {
		t.Clear()
	}
	return z
}