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C: add opt_int_div.*

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パチュリー・ノーレッジ 2024-02-24 20:05:25 +03:00
parent a73f75c489
commit 0ef6c03393
Signed by: 80486DX2-66
GPG Key ID: 83631EF27054609B
2 changed files with 91 additions and 0 deletions
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44
c-programming/math/opt_int_div.c Normal file
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/*
* opt_int_div.c
*
* Author: Intel A80486DX2-66
* License: Creative Commons Zero 1.0 Universal
*/
#include "opt_int_div.h"
#ifdef TEST
# include <inttypes.h>
# include <stdio.h>
int main(void) {
printf("Loop: a > 0, b > 0\n");
for (uint8_t a = 3; a <= 24; a++)
for (uint8_t b = 1; b <= 8; b++) {
if (b >= a)
break;
printf("%" PRIu8 " / %" PRIu8 " = %" PRIu8 "\n", a, b,
OPT_INT_DIV(a, b));
}
printf("Loop: a < 0, b > 0\n");
for (int8_t a = -3; a >= -24; a--)
for (int8_t b = 1; b <= 8; b++) {
if (b >= abs(a))
break;
printf("%" PRId8 " / %" PRId8 " = %" PRId8 "\n", a, b,
OPT_INT_DIV(a, b));
}
printf("Loop: a < 0, b < 0\n");
for (int8_t a = -3; a >= -24; a--)
for (int8_t b = -1; b >= -8; b--) {
if (b <= a)
break;
printf("%" PRId8 " / %" PRId8 " = %" PRId8 "\n", a, b,
OPT_INT_DIV(a, b));
}
return 0;
}
#endif

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c-programming/math/opt_int_div.h Normal file
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/*
* opt_int_div.h
*
* Author: Intel A80486DX2-66
* License: Creative Commons Zero 1.0 Universal
*/
#include <math.h>
#include <stdint.h>
// parameters
#define OPT_INT_DIV_TEST_PRECISION 8
// constants
#define OPT_INT_DIV_ROUNDING \
/* 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_DIV_NEG_RESULT_SIGN(a, b) (((a) < 0) ^ ((b) < 0))
#define INT_ABS(x) ((x) < 0 ? -(x) : (x))
// the main macro
#define OPT_INT_DIV(a, b) \
( /* beginning */ \
/* check for equality of a and b */ \
INT_ABS((a)) == INT_ABS((b)) ? \
/* if only one of the numbers is negative, the result is -1, */ \
/* otherwise it is 1. */ \
(INT_DIV_NEG_RESULT_SIGN(a, b) ? -1 : 1) : ( \
\
/* check if b is a power of 2 */ \
/* */ \
/* formula: round(log_2(b) % 1, OPT_INT_DIV_TEST_PRECISION digits */ \
/* after point) == 0 */ \
(roundl(fmodl(log2l((b)), 1.l) * OPT_INT_DIV_ROUNDING) / \
OPT_INT_DIV_ROUNDING == 0.l) ? ( \
/* if only one of the numbers is negative, the result is */ \
/* negative */ \
INT_DIV_NEG_RESULT_SIGN(a, b) ? \
-INT_BIN_DIV(INT_ABS(a), INT_ABS(b)) \
: \
INT_BIN_DIV(INT_ABS(a), INT_ABS(b))) \
: \
((a) / (b)) ) \
) /* end */