aboutsummaryrefslogtreecommitdiff
path: root/src/uint256.cpp
blob: 79406f24757b5ae815c905f17fc9b44f3f5c9f9f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2014 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#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(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 nun 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.
uint256& 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 uint256::GetCompact(bool fNegative) const
{
    int nSize = (bits() + 7) / 8;
    uint32_t nCompact = 0;
    if (nSize <= 3) {
        nCompact = GetLow64() << 8 * (3 - nSize);
    } else {
        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 uint256::GetHash(const 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);
}