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#ifndef UTIL_H__ |
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#define UTIL_H__ |
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|
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#if __GNUC__ >= 3 |
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# define is_constant(c) __builtin_constant_p (c) |
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#else |
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# define is_constant(c) 0 |
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#endif |
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|
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// makes dynamically allocated objects zero-initialised |
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struct zero_initialised |
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{ |
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void *operator new (size_t s); |
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void *operator new [] (size_t s); |
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void operator delete (void *p, size_t s); |
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void operator delete [] (void *p, size_t s); |
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}; |
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|
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struct str_hash |
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{ |
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std::size_t operator ()(const char *s) const |
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{ |
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unsigned long hash = 0; |
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|
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/* use the one-at-a-time hash function, which supposedly is |
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* better than the djb2-like one used by perl5.005, but |
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* certainly is better then the bug used here before. |
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* see http://burtleburtle.net/bob/hash/doobs.html |
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*/ |
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while (*s) |
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{ |
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hash += *s++; |
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hash += hash << 10; |
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hash ^= hash >> 6; |
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} |
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|
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hash += hash << 3; |
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hash ^= hash >> 11; |
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hash += hash << 15; |
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|
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return hash; |
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} |
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}; |
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|
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struct str_equal |
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{ |
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bool operator ()(const char *a, const char *b) const |
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{ |
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return !strcmp (a, b); |
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} |
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}; |
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|
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#endif |
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