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author | Janis Johnson <janis187@us.ibm.com> | 2006-09-20 16:48:21 +0000 |
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committer | Janis Johnson <janis@gcc.gnu.org> | 2006-09-20 16:48:21 +0000 |
commit | 85a92f7ef5a476cbbf36e83bb20bb304c8478d34 (patch) | |
tree | 28375452ab91a8497231c3ebaaea0d0c1222d9b1 | |
parent | 4e60515f9a6cb7a6c2fd59a9e3a1601a929deb92 (diff) | |
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extend.texi (Decimal Float): Update for latest draft TR, clean up terminology.
* doc/extend.texi (Decimal Float): Update for latest draft TR,
clean up terminology.
From-SVN: r117085
-rw-r--r-- | gcc/ChangeLog | 5 | ||||
-rw-r--r-- | gcc/doc/extend.texi | 46 |
2 files changed, 36 insertions, 15 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 640c4b9..86217ac 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2006-09-20 Janis Johnson <janis187@us.ibm.com> + + * doc/extend.texi (Decimal Float): Update for latest draft TR, + clean up terminology. + 2006-09-20 Steve Ellcey <sje@cup.hp.com> PR target/28574 diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index 625c833..fe507f2 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -33,7 +33,7 @@ extensions, accepted by GCC in C89 mode and in C++. * Conditionals:: Omitting the middle operand of a @samp{?:} expression. * Long Long:: Double-word integers---@code{long long int}. * Complex:: Data types for complex numbers. -* Decimal Float:: Decimal Floating Point. +* Decimal Float:: Decimal Floating Types. * Hex Floats:: Hexadecimal floating-point constants. * Zero Length:: Zero-length arrays. * Variable Length:: Arrays whose length is computed at run time. @@ -816,8 +816,8 @@ variables are named @code{foo$real} and @code{foo$imag}. You can examine and set these two fictitious variables with your debugger. @node Decimal Float -@section Decimal Floating Point -@cindex decimal floating point +@section Decimal Floating Types +@cindex decimal floating types @cindex @code{_Decimal32} data type @cindex @code{_Decimal64} data type @cindex @code{_Decimal128} data type @@ -828,25 +828,41 @@ examine and set these two fictitious variables with your debugger. @cindex @code{DD} integer suffix @cindex @code{DL} integer suffix -GNU C supports decimal floating point types in addition to the -standard floating-point types. This extension supports decimal -floating-point arithmetic as defined in IEEE-754R, the proposed -revision of IEEE-754. The C language extension is defined in ISO/IEC -DTR 24732, Draft 5. Support for this functionality will change when -it is accepted into the C standard and might change for new drafts -of the proposal. Calling conventions for any target might also change. -Not all targets support decimal floating point. +As an extension, the GNU C compiler supports decimal floating types as +defined in the N1176 draft of ISO/IEC WDTR24732. Support for decimal +floating types in GCC will evolve as the draft technical report changes. +Calling conventions for any target might also change. Not all targets +support decimal floating types. -Support for decimal floating point includes the arithmetic operators +The decimal floating types are @code{_Decimal32}, @code{_Decimal64}, and +@code{_Decimal128}. They use a radix of ten, unlike the floating types +@code{float}, @code{double}, and @code{long double} whose radix is not +specified by the C standard but is usually two. + +Support for decimal floating types includes the arithmetic operators add, subtract, multiply, divide; unary arithmetic operators; relational operators; equality operators; and conversions to and from -integer and other floating-point types. Use a suffix @samp{df} or +integer and other floating types. Use a suffix @samp{df} or @samp{DF} in a literal constant of type @code{_Decimal32}, @samp{dd} or @samp{DD} for @code{_Decimal64}, and @samp{dl} or @samp{DL} for @code{_Decimal128}. -Passing a decimal floating-point value as an argument to a function -without a prototype is undefined. +GCC support of decimal float as specified by the draft technical report +is incomplete: + +@itemize @bullet +@item +Translation time data type (TTDT) is not supported. + +@item +Characteristics of decimal floating types are defined in header file +@file{decfloat.h} rather than @file{float.h}. + +@item +When the value of a decimal floating type cannot be represented in the +integer type to which it is being converted, the result is undefined +rather than the result value specified by the draft technical report. +@end itemize Types @code{_Decimal32}, @code{_Decimal64}, and @code{_Decimal128} are supported by the DWARF2 debug information format. |