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opt_int_div.h: use a faster algorithm of checking

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Intel A80486DX2-66 2024-04-22 00:21:44 +03:00
parent e1b9d09a28
commit 5049a3977e
Signed by: 80486DX2-66
GPG Key ID: 83631EF27054609B
1 changed files with 4 additions and 17 deletions
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21
c-programming/math/opt_int_div.h
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@ -12,31 +12,18 @@
#include <math.h>
#include <stdint.h>
// parameters
#define OPT_INT_DIV_IS_TEST_PRECISION_LIMITED 0 /* true (1) or false (0) */
#define OPT_INT_DIV_TEST_PRECISION 8 /* only if the above parameter is 1 */
// constants
#define OPT_INT_DIV_ROUNDING \
/* formula: 10^OPT_INT_DIV_TEST_PRECISION */ \
powl(10.l, (long double) OPT_INT_DIV_TEST_PRECISION)
// helper functions
#define INT_BIN_DIV(a, b) ((a) >> (uintmax_t) log2l((b)))
#define INT_BIN_DIV(a, b) ((a) >> (uintmax_t) log2l((b))) /* NOTE: log2l may
slow things down */
#define INT_DIV_NEG_RESULT_SIGN(a, b) \
/* the sign is negative only if one of the numbers is negative */ \
(((a) < 0) != ((b) < 0)) /* 1 if sign is negative else 0 */
#define INT_ABS(x) ((x) < 0 ? -(x) : (x))
#define LOG2_DEC_PORTION(b) fmodl(log2l(INT_ABS((b))), 1.l)
#define OPT_INT_DIV_TEST(b) \
/* check if b is a power of 2 */ \
/* */ \
/* formula: round(log_2(b) % 1, OPT_INT_DIV_TEST_PRECISION digits */ \
/* after point) == 0 */ \
OPT_INT_DIV_IS_TEST_PRECISION_LIMITED ? \
roundl(LOG2_DEC_PORTION((b)) * OPT_INT_DIV_ROUNDING) == 0.l \
: \
LOG2_DEC_PORTION((b)) == 0.l
/* formula: ( X & (X - 1) ) == 0 */ \
((b) & ((b) - 1)) == 0
// the main macro
#define OPT_INT_DIV(a, b) \