words.h

00001 #ifndef CRYPTOPP_WORDS_H
00002 #define CRYPTOPP_WORDS_H
00003 
00004 #include "misc.h"
00005 
00006 NAMESPACE_BEGIN(CryptoPP)
00007 
00008 inline size_t CountWords(const word *X, size_t N)
00009 {
00010     while (N && X[N-1]==0)
00011         N--;
00012     return N;
00013 }
00014 
00015 inline void SetWords(word *r, word a, size_t n)
00016 {
00017     for (size_t i=0; i<n; i++)
00018         r[i] = a;
00019 }
00020 
00021 inline void CopyWords(word *r, const word *a, size_t n)
00022 {
00023     memcpy(r, a, n*WORD_SIZE);
00024 }
00025 
00026 inline void XorWords(word *r, const word *a, const word *b, size_t n)
00027 {
00028     for (size_t i=0; i<n; i++)
00029         r[i] = a[i] ^ b[i];
00030 }
00031 
00032 inline void XorWords(word *r, const word *a, size_t n)
00033 {
00034     for (size_t i=0; i<n; i++)
00035         r[i] ^= a[i];
00036 }
00037 
00038 inline void AndWords(word *r, const word *a, const word *b, size_t n)
00039 {
00040     for (size_t i=0; i<n; i++)
00041         r[i] = a[i] & b[i];
00042 }
00043 
00044 inline void AndWords(word *r, const word *a, size_t n)
00045 {
00046     for (size_t i=0; i<n; i++)
00047         r[i] &= a[i];
00048 }
00049 
00050 inline word ShiftWordsLeftByBits(word *r, size_t n, unsigned int shiftBits)
00051 {
00052     assert (shiftBits<WORD_BITS);
00053     word u, carry=0;
00054     if (shiftBits)
00055         for (size_t i=0; i<n; i++)
00056         {
00057             u = r[i];
00058             r[i] = (u << shiftBits) | carry;
00059             carry = u >> (WORD_BITS-shiftBits);
00060         }
00061     return carry;
00062 }
00063 
00064 inline word ShiftWordsRightByBits(word *r, size_t n, unsigned int shiftBits)
00065 {
00066     assert (shiftBits<WORD_BITS);
00067     word u, carry=0;
00068     if (shiftBits)
00069         for (size_t i=n; i>0; i--)
00070         {
00071             u = r[i-1];
00072             r[i-1] = (u >> shiftBits) | carry;
00073             carry = u << (WORD_BITS-shiftBits);
00074         }
00075     return carry;
00076 }
00077 
00078 inline void ShiftWordsLeftByWords(word *r, size_t n, size_t shiftWords)
00079 {
00080     shiftWords = STDMIN(shiftWords, n);
00081     if (shiftWords)
00082     {
00083         for (size_t i=n-1; i>=shiftWords; i--)
00084             r[i] = r[i-shiftWords];
00085         SetWords(r, 0, shiftWords);
00086     }
00087 }
00088 
00089 inline void ShiftWordsRightByWords(word *r, size_t n, size_t shiftWords)
00090 {
00091     shiftWords = STDMIN(shiftWords, n);
00092     if (shiftWords)
00093     {
00094         for (size_t i=0; i+shiftWords<n; i++)
00095             r[i] = r[i+shiftWords];
00096         SetWords(r+n-shiftWords, 0, shiftWords);
00097     }
00098 }
00099 
00100 NAMESPACE_END
00101 
00102 #endif

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