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Annotation of 43BSDReno/lib/libc/hp300/stdlib/atof.c, revision 1.1

1.1     ! root        1: /*-
        !             2:  * Copyright (c) 1990 The Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * This code is derived from software contributed to Berkeley by
        !             6:  * the Systems Programming Group of the University of Utah Computer
        !             7:  * Science Department.
        !             8:  *
        !             9:  * Redistribution and use in source and binary forms are permitted
        !            10:  * provided that: (1) source distributions retain this entire copyright
        !            11:  * notice and comment, and (2) distributions including binaries display
        !            12:  * the following acknowledgement:  ``This product includes software
        !            13:  * developed by the University of California, Berkeley and its contributors''
        !            14:  * in the documentation or other materials provided with the distribution
        !            15:  * and in all advertising materials mentioning features or use of this
        !            16:  * software. Neither the name of the University nor the names of its
        !            17:  * contributors may be used to endorse or promote products derived
        !            18:  * from this software without specific prior written permission.
        !            19:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            20:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            21:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            22:  */
        !            23: 
        !            24: #if defined(LIBC_SCCS) && !defined(lint)
        !            25: static char sccsid[] = "@(#)atof.c     5.1 (Berkeley) 5/12/90";
        !            26: #endif /* LIBC_SCCS and not lint */
        !            27: 
        !            28: #include <ctype.h>
        !            29: 
        !            30: double _twoemax =
        !            31: #ifdef IEEE
        !            32:        9007199254740992.;      /*2^53*/
        !            33: #else
        !            34:        72057594037927936.;     /*2^56*/
        !            35: #endif
        !            36: 
        !            37: #ifdef hp300
        !            38: /* attempt to be as exact as possible */
        !            39: struct {
        !            40:        long d_high;
        !            41:        long d_low;
        !            42: } _exp5[] = {
        !            43:        { 0x40140000, 0x00000000 },     /* 5 */
        !            44:        { 0x40390000, 0x00000000 },     /* 25 */
        !            45:        { 0x40838800, 0x00000000 },     /* 625 */
        !            46:        { 0x4117d784, 0x00000000 },     /* 390625 */
        !            47:        { 0x4241c379, 0x37e08000 },     /* 152587890625 */
        !            48:        { 0x4493b8b5, 0xb5056e17 },     /* 2.3283064365387e+022 */
        !            49:        { 0x49384f03, 0xe93ff9f6 },     /* 5.42101086242753e+044 */
        !            50:        { 0x52827748, 0xf9301d33 },     /* 2.93873587705572e+089 */
        !            51:        { 0x65154fdd, 0x7f73bf3f }      /* 8.63616855509445e+178 */
        !            52: };
        !            53: #else
        !            54: double _exp5[] = {
        !            55:        5.,
        !            56:        25.,
        !            57:        625.,
        !            58:        390625.,
        !            59:        152587890625.,
        !            60:        23283064365386962890625.,
        !            61: #ifdef IEEE
        !            62:        5.4210108624275231e+044,
        !            63:        2.9387358770557196e+089,
        !            64:        8.6361685550944492e+178,
        !            65: #endif
        !            66: };
        !            67: #endif
        !            68: 
        !            69: double
        !            70: atof(p)
        !            71: register char *p;
        !            72: {
        !            73:        extern double ldexp();
        !            74:        register c, exp = 0, eexp = 0;
        !            75:        double fl = 0, flexp = 1.0;
        !            76:        int bexp, neg = 1, negexp = 1;
        !            77: 
        !            78:        while((c = *p++) == ' ');
        !            79:        if (c == '-') neg = -1; else if (c == '+'); else --p;
        !            80: 
        !            81:        while ((c = *p++), isdigit(c))
        !            82:                if (fl < _twoemax) fl = 10*fl + (c-'0'); else exp++;
        !            83:        if (c == '.')
        !            84:        while ((c = *p++), isdigit(c))
        !            85:                if (fl < _twoemax)
        !            86:                {
        !            87:                        fl = 10*fl + (c-'0');
        !            88:                        exp--;
        !            89:                }
        !            90:        if ((c == 'E') || (c == 'e'))
        !            91:        {
        !            92:                if ((c= *p++) == '+'); else if (c=='-') negexp = -1; else --p;
        !            93:                while ((c = *p++), isdigit(c)) eexp = 10*eexp + (c-'0');
        !            94:                if (negexp < 0) eexp = -eexp; exp += eexp;
        !            95:        }
        !            96:        bexp = exp;
        !            97:        if (exp < 0) exp = -exp;
        !            98: 
        !            99:        for (c = 0; c < sizeof(_exp5)/sizeof(_exp5[0]); c++)
        !           100:        {
        !           101: #ifdef hp300
        !           102:                if (exp & 01) flexp *= *(double *)&_exp5[c];
        !           103: #else
        !           104:                if (exp & 01) flexp *= _exp5[c];
        !           105: #endif
        !           106:                exp >>= 1; if (exp == 0) break;
        !           107:        }
        !           108: 
        !           109:        if (bexp < 0) fl /= flexp; else fl *= flexp;
        !           110:        fl = ldexp(fl, bexp);
        !           111:        if (neg < 0) return(-fl); else return(fl);
        !           112: }

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