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/***
*gcvt.c - convert floating point number to character string
*
* Copyright (c) 1985-1991, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Converts floating point number into character string representation.
*
*Revision History:
* 09-09-93 RKW written
* 11-09-87 BCM different interface under ifdef MTHREAD
* 12-11-87 JCR Added "_LOAD_DS" to declaration
* 05-24-88 PHG Merged DLL and normal versions
* 10-20-88 JCR Changed 'DOUBLE' to 'double' for 386
* 06-27-89 PHG Changed "ndec" to "ndec-1" to correct significant
* digits in exponential format (C6 bug #2124)
* 03-05-90 GJF Fixed calling type, added #include <cruntime.h>,
* removed #include <register.h>, removed redundant
* prototypes, removed some leftover 16-bit support and
* fixed the copyright. Also, cleaned up the formatting
* a bit.
* 07-20-90 SBM Compiles cleanly with -W3 (added/removed appropriate
* #includes)
* 08-01-90 SBM Renamed <struct.h> to <fltintrn.h>
* 09-27-90 GJF New-style function declarators.
* 01-21-91 GJF ANSI naming.
* 08-13-92 SKS An old bug that was fixed in C 6.0 but that did not
* make it into C 7.0, an off by 1 error when switching
* from fixed point to scientific notation
*
*******************************************************************************/
#include <cruntime.h>
#include <fltintrn.h>
#include <internal.h>
/***
*double _gcvt(value, ndec, buffer) - convert floating point value to char
* string
*
*Purpose:
* _gcvt converts the value to a null terminated ASCII string
* buf. It attempts to produce ndigit significant digits
* in Fortran F format if possible, ortherwise E format,
* ready for printing. Trailing zeros may be suppressed.
* No error checking or overflow protection is provided.
* NOTE - to avoid the possibility of generating floating
* point instructions in this code we fool the compiler
* about the type of the 'value' parameter using a struct.
* This is OK since all we do is pass it off as a
* parameter.
*
*Entry:
* value - double - number to be converted
* ndec - int - number of significant digits
* buf - char * - buffer to place result
*
*Exit:
* result is written into buffer; it will be overwritten if it has
* not been made big enough.
*
*Exceptions:
*
*******************************************************************************/
char * _CALLTYPE1 _gcvt (
double value,
int ndec,
char *buf
)
{
#ifdef MTHREAD
struct _strflt strfltstruct; /* temporary buffers */
char resultstring[21];
#endif
STRFLT string;
int magnitude;
char *rc;
REG1 char *str;
REG2 char *stop;
/* get the magnitude of the number */
#ifdef MTHREAD
string = _fltout2( value, &strfltstruct, resultstring );
#else
string = _fltout( value );
#endif
magnitude = string->decpt - 1;
/* output the result according to the Fortran G format as outlined in
Fortran language specification */
if ( magnitude < -1 || magnitude > ndec-1 )
/* then Ew.d d = ndec */
rc = str = _cftoe( &value, buf, ndec-1, 0);
else
/* Fw.d where d = ndec-string->decpt */
rc = str = _cftof( &value, buf, ndec-string->decpt );
while (*str && *str != '.')
str++;
if (*str++) {
while (*str && *str != 'e')
str++;
stop = str--;
while (*str == '0')
str--;
while (*++str = *stop++)
;
}
return(rc);
}
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