tanjent@gmail.com | f3b7897 | 2012-03-01 03:38:55 +0000 | [diff] [blame] | 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 | |
| 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 | |
| 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 | |
| 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 > |
| 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 | |
| 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 | |
| 121 | void foo ( void ) |
| 122 | { |
| 123 | slice a; |
| 124 | slice_vec b; |
| 125 | |
| 126 | Bitslice(a,b); |
tanjent@gmail.com | f67ce94 | 2011-03-14 09:11:18 +0000 | [diff] [blame] | 127 | } |