Commit e7dd5a73 authored by Oliver Horst's avatar Oliver Horst
Browse files

[add] round function

parent 802bf22a
#ifndef _TOKI_MATH_H_
#define _TOKI_MATH_H_
double round(double x);
#endif /* _TOKI_MATH_H_ */
......@@ -2,6 +2,9 @@
// Created by ulrich on 11.05.20.
//
#ifndef _TOKI_RAND_H_
#define _TOKI_RAND_H_
#include <stddef.h>
int rand(void);
......@@ -9,3 +12,5 @@ int rand(void);
int rand_r(unsigned int *seedp);
void srand(unsigned int seed);
#endif /* _TOKI_RAND_H_ */
cmake_minimum_required(VERSION 3.7 FATAL_ERROR)
target_sources(
toki-libc-repl
#
PRIVATE
"${CMAKE_CURRENT_LIST_DIR}/round.c"
)
Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
Developed at SunPro, a Sun Microsystems, Inc. business.
Permission to use, copy, modify, and distribute this
software is freely granted, provided that this notice
is preserved.
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
FUNCTION
<<round>>, <<roundf>>---round to integer, to nearest
INDEX
round
INDEX
roundf
SYNOPSIS
#include <math.h>
double round(double <[x]>);
float roundf(float <[x]>);
DESCRIPTION
The <<round>> functions round their argument to the nearest integer
value in floating-point format, rounding halfway cases away from zero,
regardless of the current rounding direction. (While the "inexact"
floating-point exception behavior is unspecified by the C standard, the
<<round>> functions are written so that "inexact" is not raised if the
result does not equal the argument, which behavior is as recommended by
IEEE 754 for its related functions.)
RETURNS
<[x]> rounded to an integral value.
PORTABILITY
ANSI C, POSIX
SEEALSO
<<nearbyint>>, <<rint>>
*/
#include <stdint.h>
/* Get two 32 bit ints from a double. */
#define EXTRACT_WORDS(ix0,ix1,d) \
do { \
ieee_double_shape_type ew_u; \
ew_u.value = (d); \
(ix0) = ew_u.parts.msw; \
(ix1) = ew_u.parts.lsw; \
} while (0)
/* Set a double from two 32 bit ints. */
#define INSERT_WORDS(d,ix0,ix1) \
do { \
ieee_double_shape_type iw_u; \
iw_u.parts.msw = (ix0); \
iw_u.parts.lsw = (ix1); \
(d) = iw_u.value; \
} while (0)
double round(double x) {
/* Most significant word, least significant word. */
int32_t msw, exponent_less_1023;
uint32_t lsw;
EXTRACT_WORDS(msw, lsw, x);
/* Extract exponent field. */
exponent_less_1023 = ((msw & 0x7ff00000) >> 20) - 1023;
if (exponent_less_1023 < 20) {
if (exponent_less_1023 < 0) {
msw &= 0x80000000;
if (exponent_less_1023 == -1)
/* Result is +1.0 or -1.0. */
msw |= ((__int32_t) 1023 << 20);
lsw = 0;
} else {
uint32_t exponent_mask = 0x000fffff >> exponent_less_1023;
if ((msw & exponent_mask) == 0 && lsw == 0)
/* x in an integral value. */
return x;
msw += 0x00080000 >> exponent_less_1023;
msw &= ~exponent_mask;
lsw = 0;
}
} else if (exponent_less_1023 > 51) {
if (exponent_less_1023 == 1024)
/* x is NaN or infinite. */
return x + x;
else
return x;
} else {
uint32_t exponent_mask = 0xffffffff >> (exponent_less_1023 - 20);
uint32_t tmp;
if ((lsw & exponent_mask) == 0)
/* x is an integral value. */
return x;
tmp = lsw + (1 << (51 - exponent_less_1023));
if (tmp < lsw)
msw += 1;
lsw = tmp;
lsw &= ~exponent_mask;
}
INSERT_WORDS(x, msw, lsw);
return x;
}
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