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      1 /*	$NetBSD: ldtoa.c,v 1.6 2019/08/01 02:27:43 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2003 David Schultz <das (at) FreeBSD.ORG>
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 #if 0
     31 __FBSDID("$FreeBSD: src/lib/libc/gdtoa/_ldtoa.c,v 1.2 2004/01/18 07:53:49 das Exp $");
     32 #else
     33 __RCSID("$NetBSD: ldtoa.c,v 1.6 2019/08/01 02:27:43 riastradh Exp $");
     34 #endif
     35 
     36 #include <float.h>
     37 #include <inttypes.h>
     38 #include <limits.h>
     39 #include <math.h>
     40 #include <stdlib.h>
     41 #ifndef __vax__
     42 #include <machine/ieee.h>
     43 #endif
     44 #include "gdtoaimp.h"
     45 
     46 /*
     47  * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(),
     48  * except that the floating point argument is passed by reference.
     49  * When dtoa() is passed a NaN or infinity, it sets expt to 9999.
     50  * However, a long double could have a valid exponent of 9999, so we
     51  * use INT_MAX in ldtoa() instead.
     52  */
     53 char *
     54 ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign, char **rve)
     55 {
     56 #ifdef EXT_EXPBITS
     57 	static CONST FPI fpi = {
     58 		LDBL_MANT_DIG,			/* nbits */
     59 		LDBL_MIN_EXP - LDBL_MANT_DIG,	/* emin */
     60 		LDBL_MAX_EXP - LDBL_MANT_DIG,	/* emax */
     61 		FPI_Round_near,	       		/* rounding */
     62 #ifdef Sudden_Underflow	/* unused, but correct anyway */
     63 		1
     64 #else
     65 		0
     66 #endif
     67 	};
     68 	int be, kind;
     69 	char *ret;
     70 	union ieee_ext_u u;
     71 	uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
     72 
     73 	u.extu_ld = *ld;
     74 	*sign = u.extu_ext.ext_sign;
     75 	be = u.extu_ext.ext_exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
     76 	EXT_TO_ARRAY32(u, bits);
     77 
     78 	switch (fpclassify(u.extu_ld)) {
     79 	case FP_NORMAL:
     80 		kind = STRTOG_Normal;
     81 #ifdef	LDBL_IMPLICIT_NBIT
     82 		bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
     83 #endif /* LDBL_IMPLICIT_NBIT */
     84 		break;
     85 	case FP_ZERO:
     86 		kind = STRTOG_Zero;
     87 		break;
     88 	case FP_SUBNORMAL:
     89 		kind = STRTOG_Denormal;
     90 		be++;
     91 		break;
     92 	case FP_INFINITE:
     93 		kind = STRTOG_Infinite;
     94 		break;
     95 	case FP_NAN:
     96 		kind = STRTOG_NaN;
     97 		break;
     98 	default:
     99 		abort();
    100 	}
    101 
    102 	ret = gdtoa(&fpi, be, (ULong *)bits, &kind, mode, ndigits, decpt, rve);
    103 	if (*decpt == -32768)
    104 		*decpt = INT_MAX;
    105 	return ret;
    106 #else
    107 	return dtoa((double)*ld, mode, ndigits, decpt, sign, rve);
    108 #endif
    109 }
    110