6bd0dc2a84
Remove initialization from vector (as this is only used in the tests). Also implement SetHex and GetHex in terms of uint256, to avoid duplicate code as well as avoid endianness issues (as they work in term of bytes).
259 lines
7.1 KiB
C++
259 lines
7.1 KiB
C++
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2014 The Bitcoin 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 "utilstrencodings.h"
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#include <stdio.h>
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#include <string.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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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 = *this;
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*this = 0;
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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 + pn[i + j] + (uint64_t)a.pn[j] * b.pn[i];
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pn[i + j] = n & 0xffffffff;
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carry = n >> 32;
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}
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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> 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 bits = 31; bits > 0; bits--) {
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if (pn[pos] & 1 << bits)
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return 32 * pos + bits + 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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// TODO: needs bswap32 on big-endian
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memcpy(b.begin(), a.pn, a.size());
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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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// TODO: needs bswap32 on big-endian
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memcpy(b.pn, a.begin(), a.size());
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return b;
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}
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