Mercurial > jdk8-mips64-public > hotspot / file comparison
comparison: src/share/vm/libadt/dict.cpp
src/share/vm/libadt/dict.cpp
- changeset 1040
- 98cb887364d3
- parent 997
- 1580954e694c
- child 1063
- 7bb995fbd3c0
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| 1039:ec59443af135 | 1040:98cb887364d3 |
|---|---|
| 304 | 304 |
| 305 //------------------------------Hashing Functions---------------------------- | 305 //------------------------------Hashing Functions---------------------------- |
| 306 // Convert string to hash key. This algorithm implements a universal hash | 306 // Convert string to hash key. This algorithm implements a universal hash |
| 307 // function with the multipliers frozen (ok, so it's not universal). The | 307 // function with the multipliers frozen (ok, so it's not universal). The |
| 308 // multipliers (and allowable characters) are all odd, so the resultant sum | 308 // multipliers (and allowable characters) are all odd, so the resultant sum |
| 309 // is odd - guarenteed not divisible by any power of two, so the hash tables | 309 // is odd - guaranteed not divisible by any power of two, so the hash tables |
| 310 // can be any power of two with good results. Also, I choose multipliers | 310 // can be any power of two with good results. Also, I choose multipliers |
| 311 // that have only 2 bits set (the low is always set to be odd) so | 311 // that have only 2 bits set (the low is always set to be odd) so |
| 312 // multiplication requires only shifts and adds. Characters are required to | 312 // multiplication requires only shifts and adds. Characters are required to |
| 313 // be in the range 0-127 (I double & add 1 to force oddness). Keys are | 313 // be in the range 0-127 (I double & add 1 to force oddness). Keys are |
| 314 // limited to MAXID characters in length. Experimental evidence on 150K of | 314 // limited to MAXID characters in length. Experimental evidence on 150K of |
| 324 } | 324 } |
| 325 return (int)((sum+xsum[k]) >> 1); // Hash key, un-modulo'd table size | 325 return (int)((sum+xsum[k]) >> 1); // Hash key, un-modulo'd table size |
| 326 } | 326 } |
| 327 | 327 |
| 328 //------------------------------hashptr-------------------------------------- | 328 //------------------------------hashptr-------------------------------------- |
| 329 // Slimey cheap hash function; no guarenteed performance. Better than the | 329 // Slimey cheap hash function; no guaranteed performance. Better than the |
| 330 // default for pointers, especially on MS-DOS machines. | 330 // default for pointers, especially on MS-DOS machines. |
| 331 int hashptr(const void *key) { | 331 int hashptr(const void *key) { |
| 332 #ifdef __TURBOC__ | 332 #ifdef __TURBOC__ |
| 333 return ((intptr_t)key >> 16); | 333 return ((intptr_t)key >> 16); |
| 334 #else // __TURBOC__ | 334 #else // __TURBOC__ |
| 335 return ((intptr_t)key >> 2); | 335 return ((intptr_t)key >> 2); |
| 336 #endif | 336 #endif |
| 337 } | 337 } |
| 338 | 338 |
| 339 // Slimey cheap hash function; no guarenteed performance. | 339 // Slimey cheap hash function; no guaranteed performance. |
| 340 int hashkey(const void *key) { | 340 int hashkey(const void *key) { |
| 341 return (intptr_t)key; | 341 return (intptr_t)key; |
| 342 } | 342 } |
| 343 | 343 |
| 344 //------------------------------Key Comparator Functions--------------------- | 344 //------------------------------Key Comparator Functions--------------------- |
