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float.h revision 1.8 
      1 /*	$NetBSD: float.h,v 1.8 2024/06/15 11:44:09 rillig Exp $	*/
      2 
      3 #ifndef _X86_FLOAT_H_
      4 #define _X86_FLOAT_H_
      5 
      6 #include <sys/featuretest.h>
      7 
      8 /*
      9  * LDBL_MIN is twice the m68k LDBL_MIN, even though both are 12-byte
     10  * floats with the same base properties and both allegedly
     11  * IEEE-compliant, because both these representations materialize the
     12  * top (integer-part) bit of the mantissa. But on m68k if the exponent
     13  * is 0 and the integer bit is set, it's a regular number, whereas on
     14  * x86 it's called a pseudo-denormal and apparently treated as a
     15  * denormal, so it doesn't count as a valid value for LDBL_MIN.
     16  *
     17  * x86 citation: Intel 64 and IA-32 Architectures Software Developer's
     18  * Manual, vol. 1 (Order Number: 253665-077US, April 2022), Sec. 8.2.2
     19  * `Unsupported Double Extended-Precision Floating-Point Encodings
     20  * and Pseudo-Denormals', p. 8-14.
     21  *
     22  * m86k citation: MC68881/MC68882 Floating-Point Coprocessor User's
     23  * Manual, Second Edition (Prentice-Hall, 1989, apparently issued by
     24  * Freescale), Section 3.2 `Binary Real Data formats', pg. 3-3 bottom
     25  * in particular and pp. 3-2 to 3-5 in general.
     26  *
     27  * If anyone needs to update this comment please make sure the copy in
     28  * m68k/include/float.h also gets updated.
     29  */
     30 
     31 #define	LDBL_MANT_DIG	64
     32 #define LDBL_EPSILON	1.0842021724855044340E-19L
     33 #define LDBL_DIG	18
     34 #define LDBL_MIN_EXP	(-16381)
     35 #define LDBL_MIN	3.3621031431120935063E-4932L
     36 #define LDBL_MIN_10_EXP	(-4931)
     37 #define LDBL_MAX_EXP	16384
     38 #define LDBL_MAX	1.1897314953572317650E+4932L
     39 #define LDBL_MAX_10_EXP	4932
     40 
     41 #include <sys/float_ieee754.h>
     42 
     43 #if !defined(_ANSI_SOURCE) && !defined(_POSIX_C_SOURCE) && \
     44     !defined(_XOPEN_SOURCE) || \
     45     ((__STDC_VERSION__ - 0) >= 199901L) || \
     46     ((_POSIX_C_SOURCE - 0) >= 200112L) || \
     47     ((_XOPEN_SOURCE  - 0) >= 600) || \
     48     defined(_ISOC99_SOURCE) || defined(_NETBSD_SOURCE)
     49 #define	DECIMAL_DIG	21
     50 #endif /* !defined(_ANSI_SOURCE) && ... */
     51 
     52 #endif	/* _X86_FLOAT_H_ */
     53