+++ /dev/null
-/*
- * Round a number upwards to a prime (not usually the nearest one).
- *
- * Uses a table of successive 32-bit primes whose ratio is roughly
- * constant. This keeps the relative upwards 'rounding error' bounded
- * and the data size small. A simple 'predict-correct' compression is
- * used to compress primes to one byte per prime. See genhashsizes.py
- * for details.
- *
- * The minimum prime returned here must be coordinated with the possible
- * probe sequence steps in duk_hobject and duk_heap stringtable.
- */
-
-#include "duk_internal.h"
-
-/* Awkward inclusion condition: drop out of compilation if not needed by any
- * call site: object hash part or probing stringtable.
- */
-#if defined(DUK_USE_HOBJECT_HASH_PART) || defined(DUK_USE_STRTAB_PROBE)
-
-/* hash size ratio goal, must match genhashsizes.py */
-#define DUK__HASH_SIZE_RATIO 1177 /* floor(1.15 * (1 << 10)) */
-
-/* prediction corrections for prime list (see genhashsizes.py) */
-DUK_LOCAL const duk_int8_t duk__hash_size_corrections[] = {
- 17, /* minimum prime */
- 4, 3, 4, 1, 4, 1, 1, 2, 2, 2, 2, 1, 6, 6, 9, 5, 1, 2, 2, 5, 1, 3, 3, 3,
- 5, 4, 4, 2, 4, 8, 3, 4, 23, 2, 4, 7, 8, 11, 2, 12, 15, 10, 1, 1, 5, 1, 5,
- 8, 9, 17, 14, 10, 7, 5, 2, 46, 21, 1, 9, 9, 4, 4, 10, 23, 36, 6, 20, 29,
- 18, 6, 19, 21, 16, 11, 5, 5, 48, 9, 1, 39, 14, 8, 4, 29, 9, 1, 15, 48, 12,
- 22, 6, 15, 27, 4, 2, 17, 28, 8, 9, 4, 5, 8, 3, 3, 8, 37, 11, 15, 8, 30,
- 43, 6, 33, 41, 5, 20, 32, 41, 38, 24, 77, 14, 19, 11, 4, 35, 18, 19, 41,
- 10, 23, 16, 9, 2,
- -1
-};
-
-/* probe steps (see genhashsizes.py), currently assumed to be 32 entries long
- * (DUK_UTIL_GET_HASH_PROBE_STEP macro).
- */
-DUK_INTERNAL duk_uint8_t duk_util_probe_steps[32] = {
- 2, 3, 5, 7, 11, 13, 19, 31, 41, 47, 59, 67, 73, 79, 89, 101, 103, 107,
- 109, 127, 137, 139, 149, 157, 163, 167, 173, 181, 191, 193, 197, 199
-};
-
-DUK_INTERNAL duk_uint32_t duk_util_get_hash_prime(duk_uint32_t size) {
- const duk_int8_t *p = duk__hash_size_corrections;
- duk_uint32_t curr;
-
- curr = (duk_uint32_t) *p++;
- for (;;) {
- duk_small_int_t t = (duk_small_int_t) *p++;
- if (t < 0) {
- /* may happen if size is very close to 2^32-1 */
- break;
- }
-
- /* prediction: portable variant using doubles if 64-bit values not available */
-#ifdef DUK_USE_64BIT_OPS
- curr = (duk_uint32_t) ((((duk_uint64_t) curr) * ((duk_uint64_t) DUK__HASH_SIZE_RATIO)) >> 10);
-#else
- /* 32-bit x 11-bit = 43-bit, fits accurately into a double */
- curr = (duk_uint32_t) DUK_FLOOR(((double) curr) * ((double) DUK__HASH_SIZE_RATIO) / 1024.0);
-#endif
-
- /* correction */
- curr += t;
-
- DUK_DDD(DUK_DDDPRINT("size=%ld, curr=%ld", (long) size, (long) curr));
-
- if (curr >= size) {
- return curr;
- }
- }
- return 0;
-}
-
-#endif /* DUK_USE_HOBJECT_HASH_PART || DUK_USE_STRTAB_PROBE */