sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 1 | |
| 2 | #include <stdio.h> |
| 3 | #include <stdlib.h> |
| 4 | #include <assert.h> |
| 5 | |
| 6 | typedef signed int Int; |
| 7 | typedef unsigned int UInt; |
| 8 | typedef unsigned long long int Addr64; |
| 9 | typedef unsigned char UChar; |
| 10 | typedef unsigned long int UWord; |
| 11 | |
| 12 | static inline UInt ROL32 ( UInt x, UInt n ) { |
| 13 | assert(n != 0); |
| 14 | n &= 31; |
| 15 | x = (x << n) | (x >> (32-n)); |
| 16 | return x; |
| 17 | } |
| 18 | |
| 19 | ////////////////////////////////////////////////////////// |
| 20 | |
| 21 | typedef |
| 22 | struct { |
| 23 | Addr64 ga; |
| 24 | Int nbytes; |
| 25 | UChar* bytes; |
| 26 | UChar* actual; |
| 27 | } |
| 28 | GuestBytes; |
| 29 | |
| 30 | GuestBytes* read_one ( FILE* f ) |
| 31 | { |
| 32 | Int r; |
| 33 | UInt i; |
| 34 | UInt esum, csum; |
| 35 | |
| 36 | GuestBytes* gb = malloc(sizeof(GuestBytes)); |
| 37 | assert(gb); |
| 38 | |
| 39 | if (feof(f)) return NULL; |
| 40 | assert(!ferror(f)); |
| 41 | |
| 42 | r= fscanf(f, "GuestBytes %llx %d ", &gb->ga, &gb->nbytes); |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 43 | if (0) printf("r = %d\n", r); |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 44 | assert(r == 2); |
| 45 | |
| 46 | assert(gb->ga != 0); |
| 47 | assert(gb->nbytes > 0); |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 48 | assert(gb->nbytes < 5000); // let's say |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 49 | |
| 50 | Int nToAlloc = gb->nbytes + (gb->ga & 3); |
| 51 | |
| 52 | gb->bytes = malloc( gb->nbytes + nToAlloc); |
| 53 | gb->actual = gb->bytes + (gb->ga & 3); |
| 54 | assert(gb->bytes); |
| 55 | |
| 56 | csum = 0; |
| 57 | for (i = 0; i < gb->nbytes; i++) { |
| 58 | UInt b; |
| 59 | r= fscanf(f, "%02x ", &b); |
| 60 | assert(r == 1); |
| 61 | gb->actual[i] = b; |
| 62 | csum = (csum << 1) ^ b; |
| 63 | } |
| 64 | |
| 65 | r= fscanf(f, " %08x\n", &esum); |
| 66 | assert(r == 1); |
| 67 | |
| 68 | assert(esum == csum); |
| 69 | |
| 70 | return gb; |
| 71 | } |
| 72 | |
| 73 | ////////////////////////////////////////////////////////// |
| 74 | |
| 75 | void apply_to_all ( FILE* f, |
| 76 | void(*fn)( GuestBytes*, void* ), |
| 77 | void* opaque ) |
| 78 | { |
| 79 | while (!feof(f)) { |
| 80 | GuestBytes* gb = read_one(f); |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 81 | if (0) printf("got %llu %d\n", gb->ga, gb->nbytes); |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 82 | fn( gb, opaque ); |
| 83 | free(gb->bytes); |
| 84 | free(gb); |
| 85 | } |
| 86 | } |
| 87 | |
| 88 | ////////////////////////////////////////////////////////// |
| 89 | |
| 90 | UInt hash_const_zero ( GuestBytes* gb ) { |
| 91 | return 0; |
| 92 | } |
| 93 | |
| 94 | UInt hash_sum ( GuestBytes* gb ) { |
| 95 | UInt i, sum = 0; |
| 96 | for (i = 0; i < gb->nbytes; i++) |
| 97 | sum += (UInt)gb->actual[i]; |
| 98 | return sum; |
| 99 | } |
| 100 | |
| 101 | UInt hash_rol ( GuestBytes* gb ) { |
| 102 | UInt i, sum = 0; |
| 103 | for (i = 0; i < gb->nbytes; i++) { |
| 104 | sum ^= (UInt)gb->actual[i]; |
| 105 | sum = ROL32(sum,7); |
| 106 | } |
| 107 | return sum; |
| 108 | } |
| 109 | |
| 110 | static UInt cand0 ( GuestBytes* gb ) |
| 111 | { |
| 112 | UWord addr = (UWord)gb->actual; |
| 113 | UWord len = gb->nbytes; |
| 114 | UInt sum = 0; |
| 115 | /* pull up to 4-alignment */ |
| 116 | while ((addr & 3) != 0 && len >= 1) { |
| 117 | UChar* p = (UChar*)addr; |
| 118 | sum = (sum << 8) | (UInt)p[0]; |
| 119 | addr++; |
| 120 | len--; |
| 121 | } |
| 122 | /* vectorised + unrolled */ |
| 123 | while (len >= 16) { |
| 124 | UInt* p = (UInt*)addr; |
| 125 | sum = ROL32(sum ^ p[0], 13); |
| 126 | sum = ROL32(sum ^ p[1], 13); |
| 127 | sum = ROL32(sum ^ p[2], 13); |
| 128 | sum = ROL32(sum ^ p[3], 13); |
| 129 | addr += 16; |
| 130 | len -= 16; |
| 131 | } |
| 132 | /* vectorised fixup */ |
| 133 | while (len >= 4) { |
| 134 | UInt* p = (UInt*)addr; |
| 135 | sum = ROL32(sum ^ p[0], 13); |
| 136 | addr += 4; |
| 137 | len -= 4; |
| 138 | } |
| 139 | /* scalar fixup */ |
| 140 | while (len >= 1) { |
| 141 | UChar* p = (UChar*)addr; |
| 142 | sum = ROL32(sum ^ (UInt)p[0], 19); |
| 143 | addr++; |
| 144 | len--; |
| 145 | } |
| 146 | return sum; |
| 147 | } |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 148 | |
| 149 | static UInt cand1 ( GuestBytes* gb ) |
| 150 | { |
| 151 | UWord addr = (UWord)gb->actual; |
| 152 | UWord len = gb->nbytes; |
| 153 | UInt sum1 = 0, sum2 = 0; |
| 154 | /* pull up to 4-alignment */ |
| 155 | while ((addr & 3) != 0 && len >= 1) { |
| 156 | UChar* p = (UChar*)addr; |
| 157 | sum1 = (sum1 << 8) | (UInt)p[0]; |
| 158 | addr++; |
| 159 | len--; |
| 160 | } |
| 161 | /* vectorised + unrolled */ |
| 162 | while (len >= 16) { |
| 163 | UInt* p = (UInt*)addr; |
| 164 | UInt w; |
| 165 | w = p[0]; sum1 = ROL32(sum1 ^ w, 31); sum2 += w; |
| 166 | w = p[1]; sum1 = ROL32(sum1 ^ w, 31); sum2 += w; |
| 167 | w = p[2]; sum1 = ROL32(sum1 ^ w, 31); sum2 += w; |
| 168 | w = p[3]; sum1 = ROL32(sum1 ^ w, 31); sum2 += w; |
| 169 | addr += 16; |
| 170 | len -= 16; |
| 171 | sum1 ^= sum2; |
| 172 | } |
| 173 | /* vectorised fixup */ |
| 174 | while (len >= 4) { |
| 175 | UInt* p = (UInt*)addr; |
| 176 | UInt w = p[0]; |
| 177 | sum1 = ROL32(sum1 ^ w, 31); sum2 += w; |
| 178 | addr += 4; |
| 179 | len -= 4; |
| 180 | sum1 ^= sum2; |
| 181 | } |
| 182 | /* scalar fixup */ |
| 183 | while (len >= 1) { |
| 184 | UChar* p = (UChar*)addr; |
| 185 | UInt w = (UInt)p[0]; |
| 186 | sum1 = ROL32(sum1 ^ w, 31); sum2 += w; |
| 187 | addr++; |
| 188 | len--; |
| 189 | } |
| 190 | return sum1 + sum2; |
| 191 | } |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 192 | |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 193 | static UInt adler32 ( GuestBytes* gb ) |
| 194 | { |
| 195 | UWord addr = (UWord)gb->actual; |
| 196 | UWord len = gb->nbytes; |
| 197 | UInt s1 = 1; |
| 198 | UInt s2 = 0; |
| 199 | UChar* buf = (UChar*)addr; |
| 200 | while (len >= 4) { |
| 201 | s1 += buf[0]; |
| 202 | s2 += s1; |
| 203 | s1 += buf[1]; |
| 204 | s2 += s1; |
| 205 | s1 += buf[2]; |
| 206 | s2 += s1; |
| 207 | s1 += buf[3]; |
| 208 | s2 += s1; |
| 209 | buf += 4; |
| 210 | len -= 4; |
| 211 | } |
| 212 | while (len > 0) { |
| 213 | s1 += buf[0]; |
| 214 | s2 += s1; |
| 215 | len--; |
| 216 | buf++; |
| 217 | } |
| 218 | return (s2 << 16) + s1; |
| 219 | } |
| 220 | |
| 221 | |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 222 | |
| 223 | |
| 224 | ////////////////////////////////////////////////////////// |
| 225 | |
| 226 | UInt (*theFn)(GuestBytes*) = |
| 227 | //hash_const_zero; |
| 228 | //hash_sum; |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 229 | //hash_rol; |
| 230 | //cand0; |
| 231 | cand1; |
| 232 | //adler32; |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 233 | |
| 234 | Int cmp_UInt_ps ( UInt* p1, UInt* p2 ) { |
| 235 | if (*p1 < *p2) return -1; |
| 236 | if (*p1 > *p2) return 1; |
| 237 | return 0; |
| 238 | } |
| 239 | |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 240 | Int nSetBits ( UInt w ) |
| 241 | { |
| 242 | Int i, j; |
| 243 | j = 0; |
| 244 | for (i = 0; i < 32; i++) |
| 245 | if (w & (1<<i)) |
| 246 | j++; |
| 247 | return j; |
| 248 | } |
| 249 | |
| 250 | Int toc_nblocks = 0; |
| 251 | Int toc_nblocks_with_zero = 0; |
| 252 | double toc_sum_of_avgs = 0.0; |
| 253 | |
| 254 | void invertBit ( UChar* b, UInt ix, UInt bix ) { |
| 255 | b[ix] ^= (1 << bix); |
| 256 | } |
| 257 | |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 258 | void try_onebit_changes( GuestBytes* gb, void* opaque ) |
| 259 | { |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 260 | toc_nblocks++; |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 261 | /* collect up the hash values for all one bit changes of the key, |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 262 | and also that for the unmodified key. Then compute the number |
| 263 | of changed bits for all of them. */ |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 264 | UInt hashIx = 0; |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 265 | UInt nHashes = 8 * gb->nbytes; |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 266 | UInt* hashes = malloc( nHashes * sizeof(UInt) ); |
| 267 | |
| 268 | UInt byteIx, bitIx; |
| 269 | UInt hInit, hFinal, hRunning; |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 270 | Int dist, totDist = 0, nNoDist = 0; |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 271 | assert(hashes); |
| 272 | hInit = theFn( gb ); |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 273 | for (byteIx = 0; byteIx < gb->nbytes; byteIx++) { |
| 274 | for (bitIx = 0; bitIx < 8; bitIx++) { |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 275 | |
| 276 | invertBit(gb->actual, byteIx, bitIx); |
| 277 | //invertBit(gb->actual, byteIx, bitIx ^ 4); |
| 278 | |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 279 | hRunning = theFn( gb ); |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 280 | |
| 281 | dist = nSetBits(hRunning ^ hInit); |
| 282 | totDist += dist; |
| 283 | if (dist == 0) nNoDist++; |
| 284 | |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 285 | hashes[hashIx++] = hRunning; |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 286 | |
| 287 | invertBit(gb->actual, byteIx, bitIx); |
| 288 | //invertBit(gb->actual, byteIx, bitIx ^ 4); |
| 289 | |
| 290 | if (0) printf(" %02d.%d %08x %d\n", |
| 291 | byteIx, bitIx, hRunning ^ hInit, dist); |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 292 | } |
| 293 | } |
| 294 | hFinal = theFn( gb ); |
| 295 | assert(hFinal == hInit); |
| 296 | assert(hashIx == nHashes); |
| 297 | |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 298 | if (nNoDist > 0) |
| 299 | printf("%4d measurements, %5.2f avg dist, %2d zeroes\n", |
| 300 | (Int)nHashes, (double)totDist / (double)nHashes, nNoDist); |
| 301 | else |
| 302 | printf("%4d measurements, %5.2f avg dist\n", |
| 303 | (Int)nHashes, (double)totDist / (double)nHashes); |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 304 | |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 305 | if (nNoDist > 0) |
| 306 | toc_nblocks_with_zero++; |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 307 | |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 308 | toc_sum_of_avgs += (double)totDist / (double)nHashes; |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 309 | |
| 310 | free(hashes); |
| 311 | } |
| 312 | |
| 313 | ////////////////////////////////////////////////////////// |
| 314 | |
| 315 | int main ( void ) |
| 316 | { |
| 317 | FILE* f = stdin; |
| 318 | apply_to_all(f, try_onebit_changes, NULL); |
sewardj | 36af94c | 2009-09-05 00:03:52 +0000 | [diff] [blame] | 319 | printf("\n%d blocks, %d with a zero, %5.2f avg avg\n\n", |
| 320 | toc_nblocks, toc_nblocks_with_zero, toc_sum_of_avgs / (double)toc_nblocks ); |
sewardj | 1485935 | 2009-08-31 08:53:26 +0000 | [diff] [blame] | 321 | return 0; |
| 322 | } |
| 323 | |
| 324 | ////////////////////////////////////////////////////////// |