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226 lines
6.5 KiB
226 lines
6.5 KiB
![]()
4 years ago
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// words.h - originally written and placed in the public domain by Wei Dai
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/// \file words.h
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/// \brief Support functions for word operations
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#ifndef CRYPTOPP_WORDS_H
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#define CRYPTOPP_WORDS_H
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#include "config.h"
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#include "misc.h"
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NAMESPACE_BEGIN(CryptoPP)
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/// \brief Count the number of words
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/// \param x word array
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/// \param n size of the word array, in elements
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/// \returns number of words used in the array.
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/// \details CountWords counts the number of words in a word array.
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/// Leading 0-words are not included in the count.
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/// \since Crypto++ 1.0
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inline size_t CountWords(const word *x, size_t n)
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{
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while (n && x[n-1]==0)
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n--;
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return n;
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}
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/// \brief Set the value of words
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/// \param r word array
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/// \param a value
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/// \param n size of the word array, in elements
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/// \details SetWords sets all elements in the word array to the
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/// specified value.
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/// \since Crypto++ 1.0
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inline void SetWords(word *r, word a, size_t n)
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{
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for (size_t i=0; i<n; i++)
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r[i] = a;
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}
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/// \brief Copy word array
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/// \param r destination word array
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/// \param a source word array
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/// \param n size of the word array, in elements
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/// \details CopyWords copies the source word array to the destination
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/// word array.
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/// \since Crypto++ 1.0
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inline void CopyWords(word *r, const word *a, size_t n)
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{
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if (r != a)
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#if CRYPTOPP_MSC_VERSION
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memcpy_s(r, n*WORD_SIZE, a, n*WORD_SIZE);
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#else
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memcpy(r, a, n*WORD_SIZE);
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#endif
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}
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/// \brief XOR word arrays
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/// \param r destination word array
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/// \param a first source word array
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/// \param b second source word array
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/// \param n size of the word array, in elements
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/// \details XorWords XORs the two source word arrays and copies the
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/// result to the destination word array.
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/// \since Crypto++ 1.0
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inline void XorWords(word *r, const word *a, const word *b, size_t n)
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{
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for (size_t i=0; i<n; i++)
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r[i] = a[i] ^ b[i];
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}
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/// \brief XOR word arrays
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/// \param r destination word array
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/// \param a source word array
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/// \param n size of the word array, in elements
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/// \details XorWords XORs the source word array with the
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/// destination word array.
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/// \since Crypto++ 1.0
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inline void XorWords(word *r, const word *a, size_t n)
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{
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for (size_t i=0; i<n; i++)
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r[i] ^= a[i];
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}
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/// \brief AND word arrays
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/// \param r destination word array
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/// \param a first source word array
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/// \param b second source word array
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/// \param n size of the word array, in elements
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/// \details AndWords ANDs the two source word arrays and copies the
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/// result to the destination word array.
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/// \since Crypto++ 1.0
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inline void AndWords(word *r, const word *a, const word *b, size_t n)
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{
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for (size_t i=0; i<n; i++)
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r[i] = a[i] & b[i];
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}
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/// \brief AND word arrays
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/// \param r destination word array
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/// \param a source word array
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/// \param n size of the word array, in elements
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/// \details AndWords ANDs the source word array with the
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/// destination word array.
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/// \since Crypto++ 1.0
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inline void AndWords(word *r, const word *a, size_t n)
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{
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for (size_t i=0; i<n; i++)
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r[i] &= a[i];
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}
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/// \brief OR word arrays
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/// \param r destination word array
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/// \param a first source word array
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/// \param b second source word array
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/// \param n size of the word array, in elements
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/// \details OrWords ORs the two source word arrays and copies the
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/// result to the destination word array.
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/// \since Crypto++ 1.0
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inline void OrWords(word *r, const word *a, const word *b, size_t n)
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{
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for (size_t i=0; i<n; i++)
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r[i] = a[i] | b[i];
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}
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/// \brief OR word arrays
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/// \param r destination word array
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/// \param a source word array
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/// \param n size of the word array, in elements
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/// \details OrWords ORs the source word array with the
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/// destination word array.
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/// \since Crypto++ 1.0
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inline void OrWords(word *r, const word *a, size_t n)
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{
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for (size_t i=0; i<n; i++)
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r[i] |= a[i];
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}
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/// \brief Left shift word array
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/// \param r word array
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/// \param n size of the word array, in elements
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/// \param shiftBits number of bits to shift
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/// \returns word shifted out
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/// \details ShiftWordsLeftByBits shifts the word array left by
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/// shiftBits. ShiftWordsLeftByBits shifts bits out on the left;
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/// it does not extend the array.
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/// \note shiftBits must be less than WORD_BITS.
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/// \since Crypto++ 1.0
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inline word ShiftWordsLeftByBits(word *r, size_t n, unsigned int shiftBits)
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{
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CRYPTOPP_ASSERT (shiftBits<WORD_BITS);
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word u, carry=0;
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if (shiftBits)
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for (size_t i=0; i<n; i++)
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{
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u = r[i];
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r[i] = (u << shiftBits) | carry;
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carry = u >> (WORD_BITS-shiftBits);
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}
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return carry;
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}
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/// \brief Right shift word array
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/// \param r word array
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/// \param n size of the word array, in elements
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/// \param shiftBits number of bits to shift
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/// \returns word shifted out
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/// \details ShiftWordsRightByBits shifts the word array shight by
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/// shiftBits. ShiftWordsRightByBits shifts bits out on the right.
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/// \note shiftBits must be less than WORD_BITS.
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/// \since Crypto++ 1.0
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inline word ShiftWordsRightByBits(word *r, size_t n, unsigned int shiftBits)
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{
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CRYPTOPP_ASSERT (shiftBits<WORD_BITS);
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word u, carry=0;
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if (shiftBits)
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for (size_t i=n; i>0; i--)
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{
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u = r[i-1];
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r[i-1] = (u >> shiftBits) | carry;
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carry = u << (WORD_BITS-shiftBits);
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}
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return carry;
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}
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/// \brief Left shift word array
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/// \param r word array
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/// \param n size of the word array, in elements
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/// \param shiftWords number of words to shift
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/// \details ShiftWordsLeftByWords shifts the word array left by
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/// shiftWords. ShiftWordsLeftByWords shifts bits out on the left;
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/// it does not extend the array.
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/// \since Crypto++ 1.0
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inline void ShiftWordsLeftByWords(word *r, size_t n, size_t shiftWords)
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{
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shiftWords = STDMIN(shiftWords, n);
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if (shiftWords)
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{
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for (size_t i=n-1; i>=shiftWords; i--)
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r[i] = r[i-shiftWords];
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SetWords(r, 0, shiftWords);
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}
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}
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/// \brief Right shift word array
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/// \param r word array
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/// \param n size of the word array, in elements
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/// \param shiftWords number of words to shift
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/// \details ShiftWordsRightByWords shifts the word array right by
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/// shiftWords. ShiftWordsRightByWords shifts bits out on the right.
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/// \since Crypto++ 1.0
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inline void ShiftWordsRightByWords(word *r, size_t n, size_t shiftWords)
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{
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shiftWords = STDMIN(shiftWords, n);
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if (shiftWords)
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{
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for (size_t i=0; i+shiftWords<n; i++)
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r[i] = r[i+shiftWords];
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SetWords(r+n-shiftWords, 0, shiftWords);
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}
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}
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NAMESPACE_END
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#endif
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