Mercurial > ecos-v3_0-branch
diff packages/language/c/libc/stdlib/current/src/strtod.cxx @ 115:6ed91473a1cd ecos-sw-2000-08-21
Merge from eCos master repository on 2000-08-21-22:40:54-BST
| author | jlarmour |
|---|---|
| date | Fri, 25 Aug 2000 17:32:38 +0000 |
| parents | |
| children | e0c0827131d1 |
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new file mode 100644 --- /dev/null +++ b/packages/language/c/libc/stdlib/current/src/strtod.cxx @@ -0,0 +1,254 @@ +//=========================================================================== +// +// strtod.cxx +// +// ISO String to double-precision floating point conversion +// +//=========================================================================== +//####COPYRIGHTBEGIN#### +// +// ------------------------------------------- +// The contents of this file are subject to the Red Hat eCos Public License +// Version 1.1 (the "License"); you may not use this file except in +// compliance with the License. You may obtain a copy of the License at +// http://www.redhat.com/ +// +// Software distributed under the License is distributed on an "AS IS" +// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the +// License for the specific language governing rights and limitations under +// the License. +// +// The Original Code is eCos - Embedded Configurable Operating System, +// released September 30, 1998. +// +// The Initial Developer of the Original Code is Red Hat. +// Portions created by Red Hat are +// Copyright (C) 1998, 1999, 2000 Red Hat, Inc. +// All Rights Reserved. +// ------------------------------------------- +// +//####COPYRIGHTEND#### +//=========================================================================== +//#####DESCRIPTIONBEGIN#### +// +// Author(s): jlarmour +// Contributors: +// Date: 2000-04-30 +// Purpose: +// Description: +// Usage: +// +//####DESCRIPTIONEND#### +// +//=========================================================================== + +// CONFIGURATION + +#include <pkgconf/libc_stdlib.h> // Configuration header + +// Include strtod()? +#if defined(CYGFUN_LIBC_strtod) + +// INCLUDES + +#include <cyg/infra/cyg_type.h> // Common type definitions and support +#include <cyg/infra/cyg_trac.h> // Tracing support +#include <cyg/infra/cyg_ass.h> // Assertion support +#include <stddef.h> // NULL, wchar_t and size_t from compiler +#include <stdlib.h> // Main header for stdlib functions +#include <ctype.h> // isspace() and isdigit() +#include <float.h> // DBL_MIN_10_EXP and DBL_MAX_10_EXP +#include <math.h> // HUGE_VAL +#include <errno.h> // errno + +// CONSTANTS + +#define MAXE (DBL_MAX_10_EXP) +#define MINE (DBL_MIN_10_EXP) + +// flags +#define SIGN 0x01 +#define ESIGN 0x02 +#define DECP 0x04 + + +// MACROS + +#define Ise(c) ((c == 'e') || (c == 'E') || (c == 'd') || (c == 'D')) +#define Issign(c) ((c == '-') || (c == '+')) +#define Val(c) ((c - '0')) + + +// FUNCTIONS + +/* + * [atw] multiply 64 bit accumulator by 10 and add digit. + * The KA/CA way to do this should be to use + * a 64-bit integer internally and use "adjust" to + * convert it to float at the end of processing. + */ +static int +ten_mul(double *acc, int digit) +{ + /* [atw] Crude, but effective (at least on a KB)... + */ + *acc *= 10; + *acc += digit; + + return 0; /* no overflow */ +} // ten_mul() + + +/* + * compute 10**x by successive squaring. + */ + +static const double +exp10(unsigned x) +{ + static double powtab[] = {1.0, + 10.0, + 100.0, + 1000.0, + 10000.0}; + + if (x < (sizeof(powtab)/sizeof(double))) + return powtab[x]; + else if (x & 1) + return 10.0 * exp10(x-1); + else + return exp10(x/2) * exp10(x/2); +} // exp10() + + +/* + * return (*acc) scaled by 10**dexp. + */ + +static double +adjust(double *acc, int dexp, int sign) + /* *acc the 64 bit accumulator */ + /* dexp decimal exponent */ + /* sign sign flag */ +{ + double r; + + if (dexp > MAXE) + { + errno = ERANGE; + return (sign) ? -HUGE_VAL : HUGE_VAL; + } + else if (dexp < MINE) + { + errno = ERANGE; + return 0.0; + } + + r = *acc; + if (sign) + r = -r; + if (dexp==0) + return r; + + if (dexp < 0) + return r / exp10(abs(dexp)); + else + return r * exp10(dexp); +} // adjust() + + +externC double +strtod( const char *nptr, char **endptr ) +{ + const char *start=nptr; + double accum = 0.0; + int flags = 0; + int texp = 0; + int e = 0; + int conv_done = 0; + + double retval; + + CYG_REPORT_FUNCNAMETYPE( "strtod", "returning %f" ); + + CYG_CHECK_DATA_PTR( nptr, "nptr is an invalid pointer!" ); + + // endptr is allowed to be NULL, but if it isn't, we check it + if (endptr != NULL) + CYG_CHECK_DATA_PTR( endptr, "endptr is an invalid pointer!" ); + + while(isspace(*nptr)) nptr++; + if(*nptr == '\0') + { /* just leading spaces */ + if(endptr != NULL) *endptr = (char *)start; + return 0.0; + } + + + if(Issign(*nptr)) + { + if(*nptr == '-') flags = SIGN; + if(*++nptr == '\0') + { /* "+|-" : should be an error ? */ + if(endptr != NULL) *endptr = (char *)start; + return 0.0; + } + } + + for(; (isdigit(*nptr) || (*nptr == '.')); nptr++) + { + conv_done = 1; + if(*nptr == '.') + flags |= DECP; + else + { + if( ten_mul(&accum, Val(*nptr)) ) texp++; + if(flags & DECP) texp--; + } + } + + if(Ise(*nptr)) + { + conv_done = 1; + if(*++nptr != '\0') /* skip e|E|d|D */ + { /* ! ([nptr]xxx[.[yyy]]e) */ + + while(isspace(*nptr)) nptr++; /* Ansi allows spaces after e */ + if(*nptr != '\0') + { /* ! ([nptr]xxx[.[yyy]]e[space]) */ + + if(Issign(*nptr)) + if(*nptr++ == '-') flags |= ESIGN; + + if(*nptr != '\0') + { /* ! ([nptr]xxx[.[yyy]]e[nptr]) -- error?? */ + + for(; isdigit(*nptr); nptr++) + if (e < MAXE) /* prevent from grossly overflowing */ + e = e*10 + Val(*nptr); + + /* dont care what comes after this */ + if(flags & ESIGN) + texp -= e; + else + texp += e; + } + } + } + } + + if(endptr != NULL) + *endptr = (char *)((conv_done) ? nptr : start); + + retval = adjust(&accum, (int)texp, (int)(flags & SIGN)); + + + CYG_REPORT_RETVAL( retval ); + + return retval; +} // strtod() + + +#endif // if defined(CYGFUN_LIBC_strtod) + +// EOF strtod.cxx
