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260 lines
7.2 KiB
260 lines
7.2 KiB
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2019 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <arith_uint256.h>
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#include <uint256.h>
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#include <crypto/common.h>
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template <unsigned int BITS>
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base_uint<BITS>::base_uint(const std::string& str)
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{
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static_assert(BITS/32 > 0 && BITS%32 == 0, "Template parameter BITS must be a positive multiple of 32.");
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SetHex(str);
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}
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template <unsigned int BITS>
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base_uint<BITS>& base_uint<BITS>::operator<<=(unsigned int shift)
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{
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base_uint<BITS> a(*this);
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for (int i = 0; i < WIDTH; i++)
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pn[i] = 0;
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int k = shift / 32;
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shift = shift % 32;
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for (int i = 0; i < WIDTH; i++) {
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if (i + k + 1 < WIDTH && shift != 0)
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pn[i + k + 1] |= (a.pn[i] >> (32 - shift));
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if (i + k < WIDTH)
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pn[i + k] |= (a.pn[i] << shift);
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}
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return *this;
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}
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template <unsigned int BITS>
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base_uint<BITS>& base_uint<BITS>::operator>>=(unsigned int shift)
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{
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base_uint<BITS> a(*this);
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for (int i = 0; i < WIDTH; i++)
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pn[i] = 0;
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int k = shift / 32;
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shift = shift % 32;
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for (int i = 0; i < WIDTH; i++) {
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if (i - k - 1 >= 0 && shift != 0)
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pn[i - k - 1] |= (a.pn[i] << (32 - shift));
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if (i - k >= 0)
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pn[i - k] |= (a.pn[i] >> shift);
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}
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return *this;
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}
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template <unsigned int BITS>
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base_uint<BITS>& base_uint<BITS>::operator*=(uint32_t b32)
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{
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uint64_t carry = 0;
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for (int i = 0; i < WIDTH; i++) {
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uint64_t n = carry + (uint64_t)b32 * pn[i];
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pn[i] = n & 0xffffffff;
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carry = n >> 32;
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}
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return *this;
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}
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template <unsigned int BITS>
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base_uint<BITS>& base_uint<BITS>::operator*=(const base_uint& b)
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{
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base_uint<BITS> a;
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for (int j = 0; j < WIDTH; j++) {
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uint64_t carry = 0;
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for (int i = 0; i + j < WIDTH; i++) {
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uint64_t n = carry + a.pn[i + j] + (uint64_t)pn[j] * b.pn[i];
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a.pn[i + j] = n & 0xffffffff;
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carry = n >> 32;
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}
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}
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*this = a;
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return *this;
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}
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template <unsigned int BITS>
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base_uint<BITS>& base_uint<BITS>::operator/=(const base_uint& b)
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{
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base_uint<BITS> div = b; // make a copy, so we can shift.
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base_uint<BITS> num = *this; // make a copy, so we can subtract.
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*this = 0; // the quotient.
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int num_bits = num.bits();
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int div_bits = div.bits();
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if (div_bits == 0)
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throw uint_error("Division by zero");
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if (div_bits > num_bits) // the result is certainly 0.
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return *this;
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int shift = num_bits - div_bits;
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div <<= shift; // shift so that div and num align.
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while (shift >= 0) {
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if (num >= div) {
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num -= div;
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pn[shift / 32] |= (1 << (shift & 31)); // set a bit of the result.
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}
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div >>= 1; // shift back.
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shift--;
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}
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// num now contains the remainder of the division.
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return *this;
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}
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template <unsigned int BITS>
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int base_uint<BITS>::CompareTo(const base_uint<BITS>& b) const
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{
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for (int i = WIDTH - 1; i >= 0; i--) {
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if (pn[i] < b.pn[i])
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return -1;
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if (pn[i] > b.pn[i])
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return 1;
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}
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return 0;
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}
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template <unsigned int BITS>
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bool base_uint<BITS>::EqualTo(uint64_t b) const
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{
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for (int i = WIDTH - 1; i >= 2; i--) {
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if (pn[i])
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return false;
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}
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if (pn[1] != (b >> 32))
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return false;
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if (pn[0] != (b & 0xfffffffful))
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return false;
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return true;
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}
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template <unsigned int BITS>
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double base_uint<BITS>::getdouble() const
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{
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double ret = 0.0;
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double fact = 1.0;
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for (int i = 0; i < WIDTH; i++) {
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ret += fact * pn[i];
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fact *= 4294967296.0;
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}
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return ret;
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}
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template <unsigned int BITS>
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std::string base_uint<BITS>::GetHex() const
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{
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return ArithToUint256(*this).GetHex();
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}
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template <unsigned int BITS>
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void base_uint<BITS>::SetHex(const char* psz)
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{
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*this = UintToArith256(uint256S(psz));
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}
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template <unsigned int BITS>
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void base_uint<BITS>::SetHex(const std::string& str)
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{
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SetHex(str.c_str());
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}
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template <unsigned int BITS>
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std::string base_uint<BITS>::ToString() const
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{
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return (GetHex());
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}
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template <unsigned int BITS>
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unsigned int base_uint<BITS>::bits() const
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{
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for (int pos = WIDTH - 1; pos >= 0; pos--) {
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if (pn[pos]) {
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for (int nbits = 31; nbits > 0; nbits--) {
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if (pn[pos] & 1U << nbits)
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return 32 * pos + nbits + 1;
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}
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return 32 * pos + 1;
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}
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}
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return 0;
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}
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// Explicit instantiations for base_uint<256>
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template base_uint<256>::base_uint(const std::string&);
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template base_uint<256>& base_uint<256>::operator<<=(unsigned int);
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template base_uint<256>& base_uint<256>::operator>>=(unsigned int);
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template base_uint<256>& base_uint<256>::operator*=(uint32_t b32);
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template base_uint<256>& base_uint<256>::operator*=(const base_uint<256>& b);
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template base_uint<256>& base_uint<256>::operator/=(const base_uint<256>& b);
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template int base_uint<256>::CompareTo(const base_uint<256>&) const;
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template bool base_uint<256>::EqualTo(uint64_t) const;
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template double base_uint<256>::getdouble() const;
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template std::string base_uint<256>::GetHex() const;
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template std::string base_uint<256>::ToString() const;
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template void base_uint<256>::SetHex(const char*);
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template void base_uint<256>::SetHex(const std::string&);
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template unsigned int base_uint<256>::bits() const;
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// This implementation directly uses shifts instead of going
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// through an intermediate MPI representation.
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arith_uint256& arith_uint256::SetCompact(uint32_t nCompact, bool* pfNegative, bool* pfOverflow)
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{
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int nSize = nCompact >> 24;
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uint32_t nWord = nCompact & 0x007fffff;
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if (nSize <= 3) {
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nWord >>= 8 * (3 - nSize);
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*this = nWord;
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} else {
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*this = nWord;
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*this <<= 8 * (nSize - 3);
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}
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if (pfNegative)
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*pfNegative = nWord != 0 && (nCompact & 0x00800000) != 0;
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if (pfOverflow)
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*pfOverflow = nWord != 0 && ((nSize > 34) ||
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(nWord > 0xff && nSize > 33) ||
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(nWord > 0xffff && nSize > 32));
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return *this;
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}
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uint32_t arith_uint256::GetCompact(bool fNegative) const
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{
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int nSize = (bits() + 7) / 8;
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uint32_t nCompact = 0;
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if (nSize <= 3) {
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nCompact = GetLow64() << 8 * (3 - nSize);
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} else {
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arith_uint256 bn = *this >> 8 * (nSize - 3);
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nCompact = bn.GetLow64();
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}
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// The 0x00800000 bit denotes the sign.
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// Thus, if it is already set, divide the mantissa by 256 and increase the exponent.
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if (nCompact & 0x00800000) {
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nCompact >>= 8;
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nSize++;
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}
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assert((nCompact & ~0x007fffff) == 0);
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assert(nSize < 256);
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nCompact |= nSize << 24;
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nCompact |= (fNegative && (nCompact & 0x007fffff) ? 0x00800000 : 0);
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return nCompact;
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}
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uint256 ArithToUint256(const arith_uint256 &a)
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{
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uint256 b;
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for(int x=0; x<a.WIDTH; ++x)
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WriteLE32(b.begin() + x*4, a.pn[x]);
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return b;
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}
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arith_uint256 UintToArith256(const uint256 &a)
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{
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arith_uint256 b;
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for(int x=0; x<b.WIDTH; ++x)
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b.pn[x] = ReadLE32(a.begin() + x*4);
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return b;
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}
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