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Diffstat (limited to 'gcc/doc/extend.texi')
| -rw-r--r-- | gcc/doc/extend.texi | 72 |
1 files changed, 71 insertions, 1 deletions
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index b396227bb84..ebb5e375d22 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -454,6 +454,10 @@ extensions, accepted by GCC in C89 mode and in C++. * C++ Comments:: C++ comments are recognized. * Dollar Signs:: Dollar sign is allowed in identifiers. * Character Escapes:: @samp{\e} stands for the character @key{ESC}. +@c APPLE LOCAL begin Pascal strings 2001-07-05 zll ** +* Pascal Strings:: Constructing string literals with a Pascal-style + length byte. +@c APPLE LOCAL end Pascal strings 2001-07-05 zll ** * Variable Attributes:: Specifying attributes of variables. * Type Attributes:: Specifying attributes of types. * Alignment:: Inquiring about the alignment of a type or variable. @@ -2389,7 +2393,9 @@ calls are necessary. @item long_call/short_call @cindex indirect calls on ARM This attribute specifies how a particular function is called on -ARM@. Both attributes override the @option{-mlong-calls} (@pxref{ARM Options}) +@c APPLE LOCAL prune man page +ARM@. Both attributes override the @option{-mlong-calls} +@c (@pxref{ARM Options}) command line switch and @code{#pragma long_calls} settings. The @code{long_call} attribute causes the compiler to always call the function by first loading its address into a register and then using the @@ -2965,6 +2971,62 @@ machines, typically because the target assembler does not allow them. You can use the sequence @samp{\e} in a string or character constant to stand for the ASCII character @key{ESC}. +@c APPLE LOCAL begin Pascal strings 2001-07-05 zll ** +@node Pascal Strings +@section Constructing String Literals with a Pascal-style Length Byte +@cindex Pascal length byte +@cindex Pascal strings + +Specifying the @w{@option{-fpascal-strings}} option will cause the +compiler to recognize and construct Pascal-style string literals. This +functionality is disabled by default; furthermore, its use in new code +is discouraged. + +Pascal string literals take the form @samp{"\pstring"}. The special +escape sequence @samp{\p} denotes the Pascal length byte for the string, +and will be replaced at compile time with the number of characters that +follow. The @samp{\p} may only appear at the beginning of a string +literal, and may @emph{not} appear in wide string literals or as an +integral constant. + +As is the case with C string literals, Pascal string literals are +terminated with a NUL character; this character is @emph{not} counted +when computing the value of the length byte. The maximum @samp{unsigned +char} value that can be stored in the length byte is also the maximum +permissible length for the Pascal literal itself. On most target +platforms, this value is 255 (excluding both the length byte and the +terminating NUL). + +Pascal-style literals are treated by the compiler as being of type +@samp{const unsigned char []} in C++ and @samp{unsigned char []} (or +@samp{const unsigned char []}, if the @w{@option{-Wwrite-strings}} +option is given) in C. Pascal string literals may be used as static +initializers for @samp{char} arrays (whose elements need not be +@samp{unsigned} or @samp{const}). They may also be converted to +@samp{const unsigned char *} and, in the C language to @samp{const char +*} of any signedness (In C, if the @w{@option{-Wwrite-strings}} is not +given, then @samp{const} may be omitted as well). For example: + +@example +const unsigned char a[] = "\pHello"; +char b[] = "\pGoodbye"; +const unsigned char *c = "\pHello"; +const signed char *d = "\pHello"; /* error in C++ */ +char *e = "\pHi"; /* error in C++; warning in C with -Wwrite-strings */ +unsigned char *f = "\pHello"; /* error in C++ */ +@end example + +@noindent +In all other respects, Pascal-style string literals behave the same as +ordinary string literals. For example, if a program attempts to modify +the conents of a Pascal-style string literal at run-time, the behaviour +is undefined, unless the @w{@option{-fwritable-strings}} option is used. + +Pascal-style literals are useful for calling external routines that +expect Pascal strings as arguments, as is true with some Apple MacOS +Toolbox calls. +@c APPLE LOCAL end Pascal strings 2001-07-05 zll ** + @node Alignment @section Inquiring on Alignment of Types or Variables @cindex alignment @@ -6422,7 +6484,11 @@ vector unsigned int vec_mulo (vector unsigned short, vector signed int vec_mulo (vector signed short, vector signed short); vector float vec_nmsub (vector float, vector float, vector float); +@c APPLE LOCAL begin fixhtml mrs +@end smallexample +@smallexample +@c APPLE LOCAL end fixhtml mrs vector float vec_nor (vector float, vector float); vector signed int vec_nor (vector signed int, vector signed int); vector unsigned int vec_nor (vector unsigned int, vector unsigned int); @@ -6988,7 +7054,11 @@ vector signed int vec_any_eq (vector signed char, vector unsigned char); vector signed int vec_any_eq (vector signed char, vector signed char); vector signed int vec_any_eq (vector unsigned char, vector signed char); +@c APPLE LOCAL begin fixhtml mrs +@end smallexample +@smallexample +@c APPLE LOCAL end fixhtml mrs vector signed int vec_any_eq (vector unsigned char, vector unsigned char); vector signed int vec_any_eq (vector signed short, |