85 lines
2.8 KiB
C
85 lines
2.8 KiB
C
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/***
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*atof.c - convert char string to floating point number
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*
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* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* Converts a character string into a floating point number.
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*
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*Revision History:
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* 09-09-87 RKW written
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* 04-13-87 JCR added const to declaration
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* 11-09-87 BCM different interface under ifdef MTHREAD
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* 12-11-87 JCR Added "_LOAD_DS" to declaration
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* 05-24-88 PHG Merged DLL and normal versions
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* 08-18-88 PHG now calls isspace to process all kinds of whitespce
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* 10-04-88 JCR 386: Removed 'far' keyword
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* 11-20-89 JCR atof() is always _cdecl in 386 (not pascal)
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* 03-05-90 GJF Fixed calling type, added #include <cruntime.h>,
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* removed #include <register.h>, removed some redundant
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* prototypes, removed some leftover 16-bit support and
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* fixed the copyright. Also, cleaned up the formatting
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* a bit.
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* 07-20-90 SBM Compiles cleanly with -W3 (added/removed appropriate
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* #includes)
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* 08-01-90 SBM Renamed <struct.h> to <fltintrn.h>
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* 09-27-90 GJF New-style function declarator.
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* 10-21-92 GJF Made char-to-int conversion unsigned.
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* 04-06-93 SKS Replace _CRTAPI* with _cdecl
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* 09-06-94 CFW Replace MTHREAD with _MT.
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* 12-15-98 GJF Changes for 64-bit size_t.
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*
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*******************************************************************************/
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#include <stdlib.h>
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#include <math.h>
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#include <cruntime.h>
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#include <fltintrn.h>
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#include <string.h>
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#include <ctype.h>
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/***
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*double atof(nptr) - convert string to floating point number
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*
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*Purpose:
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* atof recognizes an optional string of whitespace, then
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* an optional sign, then a string of digits optionally
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* containing a decimal point, then an optional e or E followed
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* by an optionally signed integer, and converts all this to
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* to a floating point number. The first unrecognized
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* character ends the string.
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*
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*Entry:
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* nptr - pointer to string to convert
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*
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*Exit:
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* returns floating point value of character representation
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*
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*Exceptions:
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*
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*******************************************************************************/
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double __cdecl atof(
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REG1 const char *nptr
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)
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{
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#ifdef _MT
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struct _flt fltstruct; /* temporary structure */
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#endif
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/* scan past leading space/tab characters */
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while ( isspace((int)(unsigned char)*nptr) )
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nptr++;
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/* let _fltin routine do the rest of the work */
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#ifdef _MT
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return( *(double *)&(_fltin2( &fltstruct, nptr, (int)strlen(nptr), 0, 0 )->
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dval) );
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#else
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return( *(double *)&(_fltin( nptr, (int)strlen(nptr), 0, 0 )->dval) );
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#endif
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}
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