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/*************************************************
* Fused Arithmetic Operations Source File *
* (C) 1999-2005 The Botan Project *
*************************************************/
#include <botan/numthry.h>
#include <botan/mp_core.h>
namespace Botan {
/*************************************************
* Fused Multiply/Add Operation *
*************************************************/
BigInt mul_add(const BigInt& a, const BigInt& b, const BigInt& c)
{
if(c.is_negative() || c.is_zero())
throw Invalid_Argument("mul_add: Third argument must be > 0");
BigInt::Sign sign = BigInt::Positive;
if(a.sign() != b.sign())
sign = BigInt::Negative;
const u32bit a_sw = a.sig_words();
const u32bit b_sw = b.sig_words();
const u32bit c_sw = c.sig_words();
BigInt r(sign, std::max(a.size() + b.size(), c_sw) + 1);
bigint_mul3(r.get_reg(), r.size(),
a.data(), a.size(), a_sw,
b.data(), b.size(), b_sw);
const u32bit r_size = std::max(r.sig_words(), c_sw);
bigint_add2(r.get_reg(), r_size, c.data(), c_sw);
return r;
}
/*************************************************
* Fused Subtract/Multiply Operation *
*************************************************/
BigInt sub_mul(const BigInt& a, const BigInt& b, const BigInt& c)
{
if(a.is_negative() || b.is_negative())
throw Invalid_Argument("sub_mul: First two arguments must be >= 0");
BigInt r = a;
r -= b;
r *= c;
return r;
}
/*************************************************
* Fused Multiply/Modulo Operation *
*************************************************/
BigInt mul_mod(const BigInt& a, const BigInt& b, const BigInt& m)
{
if(a.is_negative() || b.is_negative())
throw Invalid_Argument("mul_mod: First two arguments must be >= 0");
if(m <= 0)
throw Invalid_Argument("mul_mod: Modulo must be positive");
BigInt r = a;
r *= b;
r %= m;
return r;
}
}
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