diff options
Diffstat (limited to 'src/lib/math/bigint/bigint.h')
| -rw-r--r-- | src/lib/math/bigint/bigint.h | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/src/lib/math/bigint/bigint.h b/src/lib/math/bigint/bigint.h index 4993f5d0c..269a74259 100644 --- a/src/lib/math/bigint/bigint.h +++ b/src/lib/math/bigint/bigint.h @@ -269,7 +269,19 @@ class BOTAN_DLL BigInt * Clear all but the lowest n bits * @param n amount of bits to keep */ - void mask_bits(size_t n); + void mask_bits(size_t n) + { + if(n == 0) { clear(); return; } + + const size_t top_word = n / BOTAN_MP_WORD_BITS; + const word mask = (static_cast<word>(1) << (n % BOTAN_MP_WORD_BITS)) - 1; + + if(top_word < size()) + { + clear_mem(&m_reg[top_word+1], size() - (top_word + 1)); + m_reg[top_word] &= mask; + } + } /** * Return bit value at specified position @@ -315,6 +327,12 @@ class BOTAN_DLL BigInt word word_at(size_t n) const { return ((n < size()) ? m_reg[n] : 0); } + void set_word_at(size_t i, word w) + { + grow_to(i + 1); + m_reg[i] = w; + } + /** * Tests if the sign of the integer is negative * @result true, iff the integer has a negative sign @@ -378,7 +396,7 @@ class BOTAN_DLL BigInt * Give byte length of the integer * @result byte length of the represented integer value */ - size_t bytes() const; + size_t bytes() const { return (bits() + 7) / 8; } /** * Get the bit length of the integer @@ -398,11 +416,18 @@ class BOTAN_DLL BigInt */ const word* data() const { return &m_reg[0]; } + secure_vector<word>& get_word_vector() { return m_reg; } + const secure_vector<word>& get_word_vector() const { return m_reg; } + /** * Increase internal register buffer to at least n words * @param n new size of register */ - void grow_to(size_t n); + void grow_to(size_t n) + { + if(n > size()) + m_reg.resize(n + (8 - n % 8)); + } /** * Fill BigInt with a random number with size of bitsize |