words.h

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// words.h - originally written and placed in the public domain by Wei Dai
 
 
#ifndef CRYPTOPP_WORDS_H
#define CRYPTOPP_WORDS_H
 
#include "config.h"
#include "misc.h"
 
NAMESPACE_BEGIN(CryptoPP)
 
 
inline size_t CountWords(const word *x, size_t n)
{
        while (n && x[n-1]==0)
                n--;
        return n;
}
 
inline void SetWords(word *r, word a, size_t n)
{
        for (size_t i=0; i<n; i++)
                r[i] = a;
}
 
inline void CopyWords(word *r, const word *a, size_t n)
{
        if (r != a)
#if CRYPTOPP_MSC_VERSION
                memcpy_s(r, n*WORD_SIZE, a, n*WORD_SIZE);
#else
                memcpy(r, a, n*WORD_SIZE);
#endif
}
 
inline void XorWords(word *r, const word *a, const word *b, size_t n)
{
        for (size_t i=0; i<n; i++)
                r[i] = a[i] ^ b[i];
}
 
inline void XorWords(word *r, const word *a, size_t n)
{
        for (size_t i=0; i<n; i++)
                r[i] ^= a[i];
}
 
inline void AndWords(word *r, const word *a, const word *b, size_t n)
{
        for (size_t i=0; i<n; i++)
                r[i] = a[i] & b[i];
}
 
inline void AndWords(word *r, const word *a, size_t n)
{
        for (size_t i=0; i<n; i++)
                r[i] &= a[i];
}
 
inline void OrWords(word *r, const word *a, const word *b, size_t n)
{
        for (size_t i=0; i<n; i++)
                r[i] = a[i] | b[i];
}
 
inline void OrWords(word *r, const word *a, size_t n)
{
        for (size_t i=0; i<n; i++)
                r[i] |= a[i];
}
 
inline word ShiftWordsLeftByBits(word *r, size_t n, unsigned int shiftBits)
{
        CRYPTOPP_ASSERT (shiftBits<WORD_BITS);
        word u, carry=0;
        if (shiftBits)
                for (size_t i=0; i<n; i++)
                {
                        u = r[i];
                        r[i] = (u << shiftBits) | carry;
                        carry = u >> (WORD_BITS-shiftBits);
                }
        return carry;
}
 
inline word ShiftWordsRightByBits(word *r, size_t n, unsigned int shiftBits)
{
        CRYPTOPP_ASSERT (shiftBits<WORD_BITS);
        word u, carry=0;
        if (shiftBits)
                for (size_t i=n; i>0; i--)
                {
                        u = r[i-1];
                        r[i-1] = (u >> shiftBits) | carry;
                        carry = u << (WORD_BITS-shiftBits);
                }
        return carry;
}
 
inline void ShiftWordsLeftByWords(word *r, size_t n, size_t shiftWords)
{
        shiftWords = STDMIN(shiftWords, n);
        if (shiftWords)
        {
                for (size_t i=n-1; i>=shiftWords; i--)
                        r[i] = r[i-shiftWords];
                SetWords(r, 0, shiftWords);
        }
}
 
inline void ShiftWordsRightByWords(word *r, size_t n, size_t shiftWords)
{
        shiftWords = STDMIN(shiftWords, n);
        if (shiftWords)
        {
                for (size_t i=0; i+shiftWords<n; i++)
                        r[i] = r[i+shiftWords];
                SetWords(r+n-shiftWords, 0, shiftWords);
        }
}
 
NAMESPACE_END
 
#endif