1 #include "Bitvec.h"
2 #include <vector>
3 #include <assert.h>
4
5 // handle xnor
6
7 typedef std::vector<uint32_t> slice;
8 typedef std::vector<slice> slice_vec;
9
countbits(slice & v)10 int countbits ( slice & v )
11 {
12 int c = 0;
13
14 for(size_t i = 0; i < v.size(); i++)
15 {
16 int d = countbits(v[i]);
17
18 c += d;
19 }
20
21 return c;
22 }
23
countxor(slice & a,slice & b)24 int countxor ( slice & a, slice & b )
25 {
26 assert(a.size() == b.size());
27
28 int c = 0;
29
30 for(size_t i = 0; i < a.size(); i++)
31 {
32 int d = countbits(a[i] ^ b[i]);
33
34 c += d;
35 }
36
37 return c;
38 }
39
xoreq(slice & a,slice & b)40 void xoreq ( slice & a, slice & b )
41 {
42 assert(a.size() == b.size());
43
44 for(size_t i = 0; i < a.size(); i++)
45 {
46 a[i] ^= b[i];
47 }
48 }
49
50 //-----------------------------------------------------------------------------
51 // Bitslice a hash set
52
53 template< typename hashtype >
Bitslice(std::vector<hashtype> & hashes,slice_vec & slices)54 void Bitslice ( std::vector<hashtype> & hashes, slice_vec & slices )
55 {
56 const int hashbytes = sizeof(hashtype);
57 const int hashbits = hashbytes * 8;
58 const int slicelen = ((int)hashes.size() + 31) / 32;
59
60 slices.clear();
61 slices.resize(hashbits);
62
63 for(int i = 0; i < (int)slices.size(); i++)
64 {
65 slices[i].resize(slicelen,0);
66 }
67
68 for(int j = 0; j < hashbits; j++)
69 {
70 void * sliceblob = &(slices[j][0]);
71
72 for(int i = 0; i < (int)hashes.size(); i++)
73 {
74 int b = getbit(hashes[i],j);
75
76 setbit(sliceblob,slicelen*4,i,b);
77 }
78 }
79 }
80
FactorSlices(slice_vec & slices)81 void FactorSlices ( slice_vec & slices )
82 {
83 std::vector<int> counts(slices.size(),0);
84
85 for(size_t i = 0; i < slices.size(); i++)
86 {
87 counts[i] = countbits(slices[i]);
88 }
89
90 bool changed = true;
91
92 while(changed)
93 {
94 int bestA = -1;
95 int bestB = -1;
96
97 for(int j = 0; j < (int)slices.size()-1; j++)
98 {
99 for(int i = j+1; i < (int)slices.size(); i++)
100 {
101 int d = countxor(slices[i],slices[j]);
102
103 if((d < counts[i]) && (d < counts[j]))
104 {
105 if(counts[i] < counts[j])
106 {
107 bestA = j;
108 bestB = i;
109 }
110 }
111 else if(d < counts[i])
112 {
113 //bestA =
114 }
115 }
116 }
117 }
118 }
119
120
foo(void)121 void foo ( void )
122 {
123 slice a;
124 slice_vec b;
125
126 Bitslice(a,b);
127 }