uint256->arith_uint256 blob256->uint256

Introduce new opaque implementation of `uint256`, move old
"arithmetic" implementation to `arith_uint256.

1 files changed, 357 insertions, 0 deletions

diff --git a/src/arith_uint256.cpp b/src/arith_uint256.cpp
new file mode 100644
index 0000000000..0dba429a8d
--- /dev/null
+++ b/src/arith_uint256.cpp
@@ -0,0 +1,357 @@
+// 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 "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(const std::vector<unsigned char>& vch)
+{
+    if (vch.size() != sizeof(pn))
+        throw uint_error("Converting vector of wrong size to base_uint");
+    memcpy(pn, &vch[0], sizeof(pn));
+}
+
+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
+{
+    char psz[sizeof(pn) * 2 + 1];
+    for (unsigned int i = 0; i < sizeof(pn); i++)
+        sprintf(psz + i * 2, "%02x", ((unsigned char*)pn)[sizeof(pn) - i - 1]);
+    return std::string(psz, psz + sizeof(pn) * 2);
+}
+
+template <unsigned int BITS>
+void base_uint<BITS>::SetHex(const char* psz)
+{
+    memset(pn, 0, sizeof(pn));
+
+    // skip leading spaces
+    while (isspace(*psz))
+        psz++;
+
+    // skip 0x
+    if (psz[0] == '0' && tolower(psz[1]) == 'x')
+        psz += 2;
+
+    // hex string to uint
+    const char* pbegin = psz;
+    while (::HexDigit(*psz) != -1)
+        psz++;
+    psz--;
+    unsigned char* p1 = (unsigned char*)pn;
+    unsigned char* pend = p1 + WIDTH * 4;
+    while (psz >= pbegin && p1 < pend) {
+        *p1 = ::HexDigit(*psz--);
+        if (psz >= pbegin) {
+            *p1 |= ((unsigned char)::HexDigit(*psz--) << 4);
+            p1++;
+        }
+    }
+}
+
+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<160>
+template base_uint<160>::base_uint(const std::string&);
+template base_uint<160>::base_uint(const std::vector<unsigned char>&);
+template base_uint<160>& base_uint<160>::operator<<=(unsigned int);
+template base_uint<160>& base_uint<160>::operator>>=(unsigned int);
+template base_uint<160>& base_uint<160>::operator*=(uint32_t b32);
+template base_uint<160>& base_uint<160>::operator*=(const base_uint<160>& b);
+template base_uint<160>& base_uint<160>::operator/=(const base_uint<160>& b);
+template int base_uint<160>::CompareTo(const base_uint<160>&) const;
+template bool base_uint<160>::EqualTo(uint64_t) const;
+template double base_uint<160>::getdouble() const;
+template std::string base_uint<160>::GetHex() const;
+template std::string base_uint<160>::ToString() const;
+template void base_uint<160>::SetHex(const char*);
+template void base_uint<160>::SetHex(const std::string&);
+template unsigned int base_uint<160>::bits() const;
+
+// Explicit instantiations for base_uint<256>
+template base_uint<256>::base_uint(const std::string&);
+template base_uint<256>::base_uint(const std::vector<unsigned char>&);
+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;
+}
+
+static void inline HashMix(uint32_t& a, uint32_t& b, uint32_t& c)
+{
+    // Taken from lookup3, by Bob Jenkins.
+    a -= c;
+    a ^= ((c << 4) | (c >> 28));
+    c += b;
+    b -= a;
+    b ^= ((a << 6) | (a >> 26));
+    a += c;
+    c -= b;
+    c ^= ((b << 8) | (b >> 24));
+    b += a;
+    a -= c;
+    a ^= ((c << 16) | (c >> 16));
+    c += b;
+    b -= a;
+    b ^= ((a << 19) | (a >> 13));
+    a += c;
+    c -= b;
+    c ^= ((b << 4) | (b >> 28));
+    b += a;
+}
+
+static void inline HashFinal(uint32_t& a, uint32_t& b, uint32_t& c)
+{
+    // Taken from lookup3, by Bob Jenkins.
+    c ^= b;
+    c -= ((b << 14) | (b >> 18));
+    a ^= c;
+    a -= ((c << 11) | (c >> 21));
+    b ^= a;
+    b -= ((a << 25) | (a >> 7));
+    c ^= b;
+    c -= ((b << 16) | (b >> 16));
+    a ^= c;
+    a -= ((c << 4) | (c >> 28));
+    b ^= a;
+    b -= ((a << 14) | (a >> 18));
+    c ^= b;
+    c -= ((b << 24) | (b >> 8));
+}
+
+uint64_t arith_uint256::GetHash(const arith_uint256& salt) const
+{
+    uint32_t a, b, c;
+    a = b = c = 0xdeadbeef + (WIDTH << 2);
+
+    a += pn[0] ^ salt.pn[0];
+    b += pn[1] ^ salt.pn[1];
+    c += pn[2] ^ salt.pn[2];
+    HashMix(a, b, c);
+    a += pn[3] ^ salt.pn[3];
+    b += pn[4] ^ salt.pn[4];
+    c += pn[5] ^ salt.pn[5];
+    HashMix(a, b, c);
+    a += pn[6] ^ salt.pn[6];
+    b += pn[7] ^ salt.pn[7];
+    HashFinal(a, b, c);
+
+    return ((((uint64_t)b) << 32) | c);
+}