HP aC++/HP ANSI C A.06.27 Release Notes

encoding". Both encodings provide exactly the same data, analogous to big endian and
little endian encodings.
• Decimal FP I/O and string conversion. The decimal FP length modifiers for printf() and
scanf() floating-point conversion specifiers (a, A, e, E, f, F, g, G) are H for _Decimal32, D
for _Decimal64, and DD for _Decimal128. The decimal a, A specifiers for printf(), given
no precision or sufficient precision, produce an exact quantum-preserving representation of
the decimal FP value being converted.
• WDB debugger support for printing values of decimal FP types.
• Suffixes to designate decimal floating constants: df or DF for _Decimal32, dd or DD for
_Decimal64, and dl or DL for _Decimal128. Note that an unsuffixed floating constant still
has type double, regardless of the context. Explicit suffixing with a d or D to specify type
double is also allowed.
• Decimal FP versions of macros in <float.h>, <math.h>, and <fenv.h>.
• Five rounding modes for decimal FP: to nearest with ties to even, to nearest with ties away
from zero, upward, downward, and toward zero.
• Compiler option +decfp, which enables full decimal FP functionality according to the ISO/IEC
C draft Technical Report: http://www.open-std.org/jtc1/sc22/wg14/www/docs/
n1312.pdf
• Compiler option -fpevaldec=precision, which specifies the minimum precision to use
for decimal floating-point expression evaluation. The possible values for precision are
_Decimal32, _Decimal64, and _Decimal128. This option does not affect the precision
of parameters, return types, or assignments. The default is -fpevaldec=_Decimal32.
• Type-generic functions in <tgmath.h> that take on the type of decimal FP (or binary FP)
arguments.
• Our Decimal FP support incorporates code from the Intel Decimal Floating-Point Math Library.
To use decimal FP:
• Install the following on an HP-UX 11i V3 (11.31) Integrity system:
core Math patch PHSS_38137◦
◦ math manpage patch PHCO_38388
◦ libc patch PHCO_38048
◦ libcEnhancement package (http://docs.hp.com/en/5992-3373/ch10s12.html)
◦ libc man page patch PHCO_37128 (for printf and scanf man pages)
• To use any decimal FP functionality (even built-in operators), add the +decfp option to the
compile and link lines.
• To use the decimal FP functionality in <math.h>, <float.h>, <fenv.h>, or <tgmath.h>,
define __STDC_WANT_DEC_FP__ before including the header.
• To use strtod32, strtod64, or strtod128, include <strtodec.h>. (These interfaces
are not declared in <stdlib.h>, as specified in the ISO/IEC C draft Technical Report.)
• Also see the “HP-UX floating-point guide for HP Integrity servers” at http://www.hp.com/go/
fp.
Decimal Floating-Point Example
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