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/* Header files. */
/* ============= */
/* Interface definitions. */
/* ---------------------- */
#include "pointset.h" /* declaration of AST__BAD etc */
/* C header files. */
/* --------------- */
#include <float.h>
#include <stdio.h>
#include <string.h>
/* Local Constants: */
#define BUFF_LEN ( 2 * DBL_DIG + 20 ) /* Buffer length */
#define IEEE_DIG 17 /* Minimum number of digits required by
IEEE for conversion from binary to
string and back again to be an
identity. */
/* Prototypes for local functions */
static void printdval( double );
static void printfval( float );
/* Main function. */
/* ============== */
int main( int argc, char *argv[] ) {
/*
*+
* Name:
* astbad
* Purpose:
* Generate a string representing an AST floating point constant.
* Invocation:
* astbad <value>
* Type:
* C program.
* Description:
* This program writes a string to standard output containing
* a formatted decimal representation of a specified C floating point
* constant defined by AST. This is intended for use in defining these
* constants for use from languages other than C.
*
* The value written should contain sufficient decimal digits so
* that a routine that uses it to generate a value in another
* language will produce exactly the same value as a C program
* using the same macro.
* Arguments:
* value = LITERAL
* The name of the constant to be printed: AST__BAD, AST__NAN or
* AST__NANF. If not supplied, AST__BAD is printed.
* Copyright:
* Copyright (C) 2009-2011 Science & Technology Facilities Council.
* Copyright (C) 1997-2006 Council for the Central Laboratory of the
* Research Councils
* Licence:
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence as
* published by the Free Software Foundation; either version 2 of
* the Licence, or (at your option) any later version.
*
* This program is distributed in the hope that it will be
* useful,but WITHOUT ANY WARRANTY; without even the implied
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public Licence for more details.
*
* You should have received a copy of the GNU General Public Licence
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street,Fifth Floor, Boston, MA
* 02110-1301, USA
* Authors:
* RFWS: R.F. Warren-Smith (Starlink)
* DSB: David S. Berry (Starlink)
* TIMJ: Tim Jenness (JAC, Hawaii)
* History:
* 18-NOV-1997 (RFWS);
* Original version.
* 24-OCT-2000 (DSB):
* Ensure that the number of digits used is at least the minimum
* required by IEEE for a conversion from binary to string and back
* to binary to be an identity.
* 31-MAR-2009 (TIMJ):
* Does not take any arguments so don't try to read arguments.
* 18-JAN-2011 (DSB):
* Extend to print other floating point constants as well as
* AST__BAD.
*-
*/
/* Local Variables; */
const char *name; /* Pointer to name of constant to be printed */
/* Get the name of the constant to be printed. */
if( argc > 1 ) {
name = argv[1];
} else {
name = "AST__BAD";
}
/* Print it. */
if( !strcmp( name, "AST__BAD" ) ) {
printdval( AST__BAD );
} else if( !strcmp( name, "AST__NAN" ) ) {
printdval( AST__NAN );
} else if( !strcmp( name, "AST__NANF" ) ) {
printfval( AST__NANF );
/* Issue an error message if the argument is unknown. */
} else {
(void) fprintf( stderr, "astbad: Unknown constant requested: %s\n",
name );
}
/* Exit. */
return 0;
}
/* Print a double precision value to standard output */
static void printdval( double val ){
/* Local Variables: */
char buff[ BUFF_LEN + 1 ]; /* Buffer for formatted string */
double newval; /* Value read back from string */
int digits; /* Number of digits of precision */
/* Vary the precision over a reasonable range to see how many decimal
digits are required. The initial number of digits is the larger of
DBL_DIG and IEEE_DIG. */
for ( digits = ( DBL_DIG > IEEE_DIG )?DBL_DIG:IEEE_DIG;
digits <= ( 2 * DBL_DIG ); digits++ ) {
/* Format the value using this precision and then read it back. */
(void) sprintf( buff, "%.*G", digits, val );
(void) sscanf( buff, "%lg", &newval );
/* Quit looping when the original value is read back. */
if ( newval == val ) break;
}
/* Write the value to standard output, with one extra digit for good
measure. */
(void) printf( "%.*G\n", digits + 1, val );
}
/* Print a single precision value to standard output */
static void printfval( float val ){
/* Local Variables: */
char buff[ BUFF_LEN + 1 ]; /* Buffer for formatted string */
float newval; /* Value read back from string */
int digits; /* Number of digits of precision */
/* Vary the precision over a reasonable range to see how many decimal
digits are required. The initial number of digits is FLT_DIG. */
for ( digits = FLT_DIG; digits <= ( 2 * FLT_DIG ); digits++ ) {
/* Format the value using this precision and then read it back. */
(void) sprintf( buff, "%.*G", digits, val );
(void) sscanf( buff, "%g", &newval );
/* Quit looping when the original value is read back. */
if ( newval == val ) break;
}
/* Write the value to standard output, with one extra digit for good
measure. */
(void) printf( "%.*G\n", digits + 1, val );
}
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