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Diffstat (limited to 'innobase/include/ut0rnd.ic')
| -rw-r--r-- | innobase/include/ut0rnd.ic | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/innobase/include/ut0rnd.ic b/innobase/include/ut0rnd.ic new file mode 100644 index 00000000000..e166a26fe86 --- /dev/null +++ b/innobase/include/ut0rnd.ic @@ -0,0 +1,222 @@ +/****************************************************************** +Random numbers and hashing + +(c) 1994, 1995 Innobase Oy + +Created 5/30/1994 Heikki Tuuri +*******************************************************************/ + +#define UT_HASH_RANDOM_MASK 1463735687 +#define UT_HASH_RANDOM_MASK2 1653893711 +#define UT_RND1 151117737 +#define UT_RND2 119785373 +#define UT_RND3 85689495 +#define UT_RND4 76595339 +#define UT_SUM_RND2 98781234 +#define UT_SUM_RND3 126792457 +#define UT_SUM_RND4 63498502 +#define UT_XOR_RND1 187678878 +#define UT_XOR_RND2 143537923 + +extern ulint ut_rnd_ulint_counter; + +/************************************************************ +This is used to set the random number seed. */ +UNIV_INLINE +void +ut_rnd_set_seed( +/*============*/ + ulint seed) /* in: seed */ +{ + ut_rnd_ulint_counter = seed; +} + +/************************************************************ +The following function generates a series of 'random' ulint integers. */ +UNIV_INLINE +ulint +ut_rnd_gen_next_ulint( +/*==================*/ + /* out: the next 'random' number */ + ulint rnd) /* in: the previous random number value */ +{ + ulint n_bits; + + n_bits = 8 * sizeof(ulint); + + rnd = UT_RND2 * rnd + UT_SUM_RND3; + rnd = UT_XOR_RND1 ^ rnd; + rnd = (rnd << 20) + (rnd >> (n_bits - 20)); + rnd = UT_RND3 * rnd + UT_SUM_RND4; + rnd = UT_XOR_RND2 ^ rnd; + rnd = (rnd << 20) + (rnd >> (n_bits - 20)); + rnd = UT_RND1 * rnd + UT_SUM_RND2; + + return(rnd); +} + +/************************************************************ +The following function generates 'random' ulint integers which +enumerate the value space of ulint integers in a pseudo random +fashion. Note that the same integer is repeated always after +2 to power 32 calls to the generator (if ulint is 32-bit). */ +UNIV_INLINE +ulint +ut_rnd_gen_ulint(void) +/*==================*/ + /* out: the 'random' number */ +{ + ulint rnd; + ulint n_bits; + + n_bits = 8 * sizeof(ulint); + + ut_rnd_ulint_counter = + UT_RND1 * ut_rnd_ulint_counter + UT_RND2; + + rnd = ut_rnd_gen_next_ulint(ut_rnd_ulint_counter); + + return(rnd); +} + +/************************************************************ +Generates a random integer from a given interval. */ +UNIV_INLINE +ulint +ut_rnd_interval( +/*============*/ + /* out: the 'random' number */ + ulint low, /* in: low limit; can generate also this value */ + ulint high) /* in: high limit; can generate also this value */ +{ + ulint rnd; + + ut_ad(high >= low); + + if (low == high) { + + return(low); + } + + rnd = ut_rnd_gen_ulint(); + + return(low + (rnd % (high - low + 1))); +} + +/************************************************************* +Generates a random iboolean value. */ +UNIV_INLINE +ibool +ut_rnd_gen_ibool(void) +/*=================*/ + /* out: the random value */ +{ + ulint x; + + x = ut_rnd_gen_ulint(); + + if (((x >> 20) + (x >> 15)) & 1) { + + return(TRUE); + } + + return(FALSE); +} + +/*********************************************************** +The following function generates a hash value for a ulint integer +to a hash table of size table_size, which should be a prime +or some random number for the hash table to work reliably. */ +UNIV_INLINE +ulint +ut_hash_ulint( +/*=========*/ + /* out: hash value */ + ulint key, /* in: value to be hashed */ + ulint table_size) /* in: hash table size */ +{ + key = key ^ UT_HASH_RANDOM_MASK2; + + return(key % table_size); +} + +/***************************************************************** +Folds a pair of ulints. */ +UNIV_INLINE +ulint +ut_fold_ulint_pair( +/*===============*/ + /* out: folded value */ + ulint n1, /* in: ulint */ + ulint n2) /* in: ulint */ +{ + return(((((n1 ^ n2 ^ UT_HASH_RANDOM_MASK2) << 8) + n1) + ^ UT_HASH_RANDOM_MASK) + n2); +} + +/***************************************************************** +Folds a dulint. */ +UNIV_INLINE +ulint +ut_fold_dulint( +/*===========*/ + /* out: folded value */ + dulint d) /* in: dulint */ +{ + return(ut_fold_ulint_pair(ut_dulint_get_low(d), + ut_dulint_get_high(d))); +} + +/***************************************************************** +Folds a character string ending in the null character. */ +UNIV_INLINE +ulint +ut_fold_string( +/*===========*/ + /* out: folded value */ + char* str) /* in: null-terminated string */ +{ + #ifdef UNIV_DEBUG + ulint i = 0; + #endif + ulint fold = 0; + + ut_ad(str); + + while (*str != '\0') { + + #ifdef UNIV_DEBUG + i++; + ut_a(i < 100); + #endif + + fold = ut_fold_ulint_pair(fold, (ulint)(*str)); + str++; + } + + return(fold); +} + +/***************************************************************** +Folds a binary string. */ +UNIV_INLINE +ulint +ut_fold_binary( +/*===========*/ + /* out: folded value */ + byte* str, /* in: string of bytes */ + ulint len) /* in: length */ +{ + ulint i; + ulint fold = 0; + + ut_ad(str); + + for (i = 0; i < len; i++) { + fold = ut_fold_ulint_pair(fold, (ulint)(*str)); + + str++; + } + + return(fold); +} |