cscg22-gearboy

CSCG 2022 Challenge 'Gearboy'
git clone https://git.sinitax.com/sinitax/cscg22-gearboy
Log | Files | Refs | sfeed.txt

s_floor.c (2641B)

      1/* @(#)s_floor.c 5.1 93/09/24 */
      2/*
      3 * ====================================================
      4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
      5 *
      6 * Developed at SunPro, a Sun Microsystems, Inc. business.
      7 * Permission to use, copy, modify, and distribute this
      8 * software is freely granted, provided that this notice
      9 * is preserved.
     10 * ====================================================
     11 */
     12
     13#if defined(LIBM_SCCS) && !defined(lint)
     14static const char rcsid[] =
     15    "$NetBSD: s_floor.c,v 1.8 1995/05/10 20:47:20 jtc Exp $";
     16#endif
     17
     18/*
     19 * floor(x)
     20 * Return x rounded toward -inf to integral value
     21 * Method:
     22 *	Bit twiddling.
     23 * Exception:
     24 *	Inexact flag raised if x not equal to floor(x).
     25 */
     26
     27#include "math_libm.h"
     28#include "math_private.h"
     29
     30#ifdef __STDC__
     31static const double huge_val = 1.0e300;
     32#else
     33static double huge_val = 1.0e300;
     34#endif
     35
     36libm_hidden_proto(floor)
     37#ifdef __STDC__
     38     double floor(double x)
     39#else
     40     double floor(x)
     41     double x;
     42#endif
     43{
     44    int32_t i0, i1, j0;
     45    u_int32_t i, j;
     46    EXTRACT_WORDS(i0, i1, x);
     47    j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
     48    if (j0 < 20) {
     49        if (j0 < 0) {           /* raise inexact if x != 0 */
     50            if (huge_val + x > 0.0) {       /* return 0*sign(x) if |x|<1 */
     51                if (i0 >= 0) {
     52                    i0 = i1 = 0;
     53                } else if (((i0 & 0x7fffffff) | i1) != 0) {
     54                    i0 = 0xbff00000;
     55                    i1 = 0;
     56                }
     57            }
     58        } else {
     59            i = (0x000fffff) >> j0;
     60            if (((i0 & i) | i1) == 0)
     61                return x;       /* x is integral */
     62            if (huge_val + x > 0.0) {       /* raise inexact flag */
     63                if (i0 < 0)
     64                    i0 += (0x00100000) >> j0;
     65                i0 &= (~i);
     66                i1 = 0;
     67            }
     68        }
     69    } else if (j0 > 51) {
     70        if (j0 == 0x400)
     71            return x + x;       /* inf or NaN */
     72        else
     73            return x;           /* x is integral */
     74    } else {
     75        i = ((u_int32_t) (0xffffffff)) >> (j0 - 20);
     76        if ((i1 & i) == 0)
     77            return x;           /* x is integral */
     78        if (huge_val + x > 0.0) {   /* raise inexact flag */
     79            if (i0 < 0) {
     80                if (j0 == 20)
     81                    i0 += 1;
     82                else {
     83                    j = i1 + (1 << (52 - j0));
     84                    if (j < (u_int32_t) i1)
     85                        i0 += 1;        /* got a carry */
     86                    i1 = j;
     87                }
     88            }
     89            i1 &= (~i);
     90        }
     91    }
     92    INSERT_WORDS(x, i0, i1);
     93    return x;
     94}
     95
     96libm_hidden_def(floor)