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#pragma once
/**
@file
@brief definition of Unit and some functions
@author MITSUNARI Shigeo(@herumi)
@license modified new BSD license
http://opensource.org/licenses/BSD-3-Clause
*/
#include <mcl/gmp_util.hpp>
namespace mcl { namespace fp {
/*
get pp such that p * pp = -1 mod M,
where p is prime and M = 1 << 64(or 32).
@param pLow [in] p mod M
*/
template<class T>
T getMontgomeryCoeff(T pLow)
{
T ret = 0;
T t = 0;
T x = 1;
for (size_t i = 0; i < sizeof(T) * 8; i++) {
if ((t & 1) == 0) {
t += pLow;
ret += x;
}
t >>= 1;
x <<= 1;
}
return ret;
}
template<class T>
int compareArray(const T* x, const T* y, size_t n)
{
for (size_t i = n - 1; i != size_t(-1); i--) {
if (x[i] < y[i]) return -1;
if (x[i] > y[i]) return 1;
}
return 0;
}
template<class T>
bool isEqualArray(const T* x, const T* y, size_t n)
{
for (size_t i = 0; i < n; i++) {
if (x[i] != y[i]) return false;
}
return true;
}
template<class T>
bool isZeroArray(const T *x, size_t n)
{
for (size_t i = 0; i < n; i++) {
if (x[i]) return false;
}
return true;
}
template<class T>
void clearArray(T *x, size_t begin, size_t end)
{
for (size_t i = begin; i < end; i++) x[i] = 0;
}
template<class T>
void copyArray(T *y, const T *x, size_t n)
{
for (size_t i = 0; i < n; i++) y[i] = x[i];
}
template<class T>
void toArray(T *y, size_t yn, const mpz_srcptr x)
{
const int xn = x->_mp_size;
assert(xn >= 0);
const T* xp = (const T*)x->_mp_d;
assert(xn <= (int)yn);
copyArray(y, xp, xn);
clearArray(y, xn, yn);
}
/*
get random value less than in[]
n = (bitLen + sizeof(T) * 8) / (sizeof(T) * 8)
input in[0..n)
output out[n..n)
0 <= out < in
*/
template<class RG, class T>
void getRandVal(T *out, RG& rg, const T *in, size_t bitLen)
{
const size_t TBitN = sizeof(T) * 8;
const size_t n = (bitLen + TBitN - 1) / TBitN;
const size_t rem = bitLen & (TBitN - 1);
for (;;) {
rg.read(out, n);
if (rem > 0) out[n - 1] &= (T(1) << rem) - 1;
if (compareArray(out, in, n) < 0) return;
}
}
} } // mcl::fp
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