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Diffstat (limited to 'src/arith_uint256.cpp')
| -rw-r--r-- | src/arith_uint256.cpp | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/src/arith_uint256.cpp b/src/arith_uint256.cpp new file mode 100644 index 0000000000..1243823da5 --- /dev/null +++ b/src/arith_uint256.cpp @@ -0,0 +1,259 @@ +// Copyright (c) 2009-2010 Satoshi Nakamoto +// Copyright (c) 2009-2014 The Bitcoin developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#include "arith_uint256.h" + +#include "uint256.h" +#include "utilstrencodings.h" + +#include <stdio.h> +#include <string.h> + +template <unsigned int BITS> +base_uint<BITS>::base_uint(const std::string& str) +{ + SetHex(str); +} + +template <unsigned int BITS> +base_uint<BITS>& base_uint<BITS>::operator<<=(unsigned int shift) +{ + base_uint<BITS> a(*this); + for (int i = 0; i < WIDTH; i++) + pn[i] = 0; + int k = shift / 32; + shift = shift % 32; + for (int i = 0; i < WIDTH; i++) { + if (i + k + 1 < WIDTH && shift != 0) + pn[i + k + 1] |= (a.pn[i] >> (32 - shift)); + if (i + k < WIDTH) + pn[i + k] |= (a.pn[i] << shift); + } + return *this; +} + +template <unsigned int BITS> +base_uint<BITS>& base_uint<BITS>::operator>>=(unsigned int shift) +{ + base_uint<BITS> a(*this); + for (int i = 0; i < WIDTH; i++) + pn[i] = 0; + int k = shift / 32; + shift = shift % 32; + for (int i = 0; i < WIDTH; i++) { + if (i - k - 1 >= 0 && shift != 0) + pn[i - k - 1] |= (a.pn[i] << (32 - shift)); + if (i - k >= 0) + pn[i - k] |= (a.pn[i] >> shift); + } + return *this; +} + +template <unsigned int BITS> +base_uint<BITS>& base_uint<BITS>::operator*=(uint32_t b32) +{ + uint64_t carry = 0; + for (int i = 0; i < WIDTH; i++) { + uint64_t n = carry + (uint64_t)b32 * pn[i]; + pn[i] = n & 0xffffffff; + carry = n >> 32; + } + return *this; +} + +template <unsigned int BITS> +base_uint<BITS>& base_uint<BITS>::operator*=(const base_uint& b) +{ + base_uint<BITS> a = *this; + *this = 0; + for (int j = 0; j < WIDTH; j++) { + uint64_t carry = 0; + for (int i = 0; i + j < WIDTH; i++) { + uint64_t n = carry + pn[i + j] + (uint64_t)a.pn[j] * b.pn[i]; + pn[i + j] = n & 0xffffffff; + carry = n >> 32; + } + } + return *this; +} + +template <unsigned int BITS> +base_uint<BITS>& base_uint<BITS>::operator/=(const base_uint& b) +{ + base_uint<BITS> div = b; // make a copy, so we can shift. + base_uint<BITS> num = *this; // make a copy, so we can subtract. + *this = 0; // the quotient. + int num_bits = num.bits(); + int div_bits = div.bits(); + if (div_bits == 0) + throw uint_error("Division by zero"); + if (div_bits > num_bits) // the result is certainly 0. + return *this; + int shift = num_bits - div_bits; + div <<= shift; // shift so that div and num align. + while (shift >= 0) { + if (num >= div) { + num -= div; + pn[shift / 32] |= (1 << (shift & 31)); // set a bit of the result. + } + div >>= 1; // shift back. + shift--; + } + // num now contains the remainder of the division. + return *this; +} + +template <unsigned int BITS> +int base_uint<BITS>::CompareTo(const base_uint<BITS>& b) const +{ + for (int i = WIDTH - 1; i >= 0; i--) { + if (pn[i] < b.pn[i]) + return -1; + if (pn[i] > b.pn[i]) + return 1; + } + return 0; +} + +template <unsigned int BITS> +bool base_uint<BITS>::EqualTo(uint64_t b) const +{ + for (int i = WIDTH - 1; i >= 2; i--) { + if (pn[i]) + return false; + } + if (pn[1] != (b >> 32)) + return false; + if (pn[0] != (b & 0xfffffffful)) + return false; + return true; +} + +template <unsigned int BITS> +double base_uint<BITS>::getdouble() const +{ + double ret = 0.0; + double fact = 1.0; + for (int i = 0; i < WIDTH; i++) { + ret += fact * pn[i]; + fact *= 4294967296.0; + } + return ret; +} + +template <unsigned int BITS> +std::string base_uint<BITS>::GetHex() const +{ + return ArithToUint256(*this).GetHex(); +} + +template <unsigned int BITS> +void base_uint<BITS>::SetHex(const char* psz) +{ + *this = UintToArith256(uint256S(psz)); +} + +template <unsigned int BITS> +void base_uint<BITS>::SetHex(const std::string& str) +{ + SetHex(str.c_str()); +} + +template <unsigned int BITS> +std::string base_uint<BITS>::ToString() const +{ + return (GetHex()); +} + +template <unsigned int BITS> +unsigned int base_uint<BITS>::bits() const +{ + for (int pos = WIDTH - 1; pos >= 0; pos--) { + if (pn[pos]) { + for (int bits = 31; bits > 0; bits--) { + if (pn[pos] & 1 << bits) + return 32 * pos + bits + 1; + } + return 32 * pos + 1; + } + } + return 0; +} + +// Explicit instantiations for base_uint<256> +template base_uint<256>::base_uint(const std::string&); +template base_uint<256>& base_uint<256>::operator<<=(unsigned int); +template base_uint<256>& base_uint<256>::operator>>=(unsigned int); +template base_uint<256>& base_uint<256>::operator*=(uint32_t b32); +template base_uint<256>& base_uint<256>::operator*=(const base_uint<256>& b); +template base_uint<256>& base_uint<256>::operator/=(const base_uint<256>& b); +template int base_uint<256>::CompareTo(const base_uint<256>&) const; +template bool base_uint<256>::EqualTo(uint64_t) const; +template double base_uint<256>::getdouble() const; +template std::string base_uint<256>::GetHex() const; +template std::string base_uint<256>::ToString() const; +template void base_uint<256>::SetHex(const char*); +template void base_uint<256>::SetHex(const std::string&); +template unsigned int base_uint<256>::bits() const; + +// This implementation directly uses shifts instead of going +// through an intermediate MPI representation. +arith_uint256& arith_uint256::SetCompact(uint32_t nCompact, bool* pfNegative, bool* pfOverflow) +{ + int nSize = nCompact >> 24; + uint32_t nWord = nCompact & 0x007fffff; + if (nSize <= 3) { + nWord >>= 8 * (3 - nSize); + *this = nWord; + } else { + *this = nWord; + *this <<= 8 * (nSize - 3); + } + if (pfNegative) + *pfNegative = nWord != 0 && (nCompact & 0x00800000) != 0; + if (pfOverflow) + *pfOverflow = nWord != 0 && ((nSize > 34) || + (nWord > 0xff && nSize > 33) || + (nWord > 0xffff && nSize > 32)); + return *this; +} + +uint32_t arith_uint256::GetCompact(bool fNegative) const +{ + int nSize = (bits() + 7) / 8; + uint32_t nCompact = 0; + if (nSize <= 3) { + nCompact = GetLow64() << 8 * (3 - nSize); + } else { + arith_uint256 bn = *this >> 8 * (nSize - 3); + nCompact = bn.GetLow64(); + } + // The 0x00800000 bit denotes the sign. + // Thus, if it is already set, divide the mantissa by 256 and increase the exponent. + if (nCompact & 0x00800000) { + nCompact >>= 8; + nSize++; + } + assert((nCompact & ~0x007fffff) == 0); + assert(nSize < 256); + nCompact |= nSize << 24; + nCompact |= (fNegative && (nCompact & 0x007fffff) ? 0x00800000 : 0); + return nCompact; +} + +uint256 ArithToUint256(const arith_uint256 &a) +{ + uint256 b; + // TODO: needs bswap32 on big-endian + memcpy(b.begin(), a.pn, a.size()); + return b; +} +arith_uint256 UintToArith256(const uint256 &a) +{ + arith_uint256 b; + // TODO: needs bswap32 on big-endian + memcpy(b.pn, a.begin(), a.size()); + return b; +} |