gonzui

    1: /*      $OpenBSD: s_lround.c,v 1.4 2011/07/06 00:02:42 martynas Exp $        */
    2: /* $NetBSD: lround.c,v 1.2 2004/10/13 15:18:32 drochner Exp $ */
    3: 
    4: /*-
    5:  * Copyright (c) 2004
    6:  *      Matthias Drochner. All rights reserved.
    7:  *
    8:  * Redistribution and use in source and binary forms, with or without
    9:  * modification, are permitted provided that the following conditions
   10:  * are met:
   11:  * 1. Redistributions of source code must retain the above copyright
   12:  *    notice, this list of conditions and the following disclaimer.
   13:  * 2. Redistributions in binary form must reproduce the above copyright
   14:  *    notice, this list of conditions and the following disclaimer in the
   15:  *    documentation and/or other materials provided with the distribution.
   16:  *
   17:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   18:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   21:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27:  * SUCH DAMAGE.
   28:  */
   29: 
   30: /* LINTLIBRARY */
   31: 
   32: #include <sys/types.h>
   33: #include <sys/limits.h>
   34: #include <float.h>
   35: #include <math.h>
   36: #include <ieeefp.h>
   37: #include <machine/ieee.h>
   38: #include "math_private.h"
   39: 
   40: #ifndef LROUNDNAME
   41: #define LROUNDNAME lround
   42: #define RESTYPE long int
   43: #define RESTYPE_MIN LONG_MIN
   44: #define RESTYPE_MAX LONG_MAX
   45: #endif
   46: 
   47: #define RESTYPE_BITS (sizeof(RESTYPE) * 8)
   48: 
   49: RESTYPE
   50: LROUNDNAME(double x)
   51: {
   52:         u_int32_t i0, i1;
   53:         int e, s, shift;
   54:         RESTYPE res;
   55: 
   56:         GET_HIGH_WORD(i0, x);
   57:         e = i0 >> DBL_FRACHBITS;
   58:         s = e >> DBL_EXPBITS;
   59:         e = (e & 0x7ff) - DBL_EXP_BIAS;
   60: 
   61:         /* 1.0 x 2^-1 is the smallest number which can be rounded to 1 */
   62:         if (e < -1)
   63:                 return (0);
   64:         /* 1.0 x 2^31 (or 2^63) is already too large */
   65:         if (e >= (int)RESTYPE_BITS - 1)
   66:                 return (s ? RESTYPE_MIN : RESTYPE_MAX); /* ??? unspecified */
   67: 
   68:         /* >= 2^52 is already an exact integer */
   69:         if (e < DBL_FRACBITS) {
   70:                 /* add 0.5, extraction below will truncate */
   71:                 x += (s ? -0.5 : 0.5);
   72:         }
   73: 
   74:         EXTRACT_WORDS(i0, i1, x);
   75:         e = ((i0 >> DBL_FRACHBITS) & 0x7ff) - DBL_EXP_BIAS;
   76:         i0 &= 0xfffff;
   77:         i0 |= (1 << DBL_FRACHBITS);
   78: 
   79:         shift = e - DBL_FRACBITS;
   80:         if (shift >=0)
   81:                 res = (shift < RESTYPE_BITS ? (RESTYPE)i1 << shift : 0);
   82:         else
   83:                 res = (shift > -RESTYPE_BITS ? (RESTYPE)i1 >> -shift : 0);
   84:         shift += 32;
   85:         if (shift >=0)
   86:                 res |= (shift < RESTYPE_BITS ? (RESTYPE)i0 << shift : 0);
   87:         else
   88:                 res |= (shift > -RESTYPE_BITS ? (RESTYPE)i0 >> -shift : 0);
   89: 
   90:         return (s ? -res : res);
   91: }
   92: 
   93: #if     LDBL_MANT_DIG == 53
   94: #ifdef  lint
   95: /* PROTOLIB1 */
   96: long int lroundl(long double);
   97: #else   /* lint */
   98: __weak_alias(lroundl, lround);
   99: #endif  /* lint */
  100: #endif  /* LDBL_MANT_DIG == 53 */