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On OpenVMS VAX systems, the CC command is used to invoke either the VAX C or Compaq C compiler. If your system has a VAX C compiler already installed on it, the Compaq C installation procedure provides the option of specifying which compiler will be invoked by default when just the CC command is used. To invoke the compiler that is not the default, use the CC command with the appropriate qualifier: CC/DECC for the Compaq C compiler, or CC/VAXC for the VAX C compiler. If your system does not have a VAX C compiler installed on it, the CC command will invoke the Compaq C compiler.
On OpenVMS Alpha systems, specifying /DECC is equivalent to not specifying it; this qualifier is supported to provide compatibility with Compaq C on OpenVMS VAX systems.
Since /DEFINE and /UNDEFINE are not part of the source file, they are not associated with a listing line number or source line number. Therefore, when an error occurs in a command-line definition, the message displayed at the terminal does not indicate a line number. In the listing file, these diagnostic messages are placed before the source listing in the order that they were encountered. When the expansion of a definition causes an error at a specific source line in the program, the diagnostics---both at the terminal and in the listing file---are associated with that source line.
A command line containing the /DEFINE and the /UNDEFINE qualifiers can be long. Continuation characters cannot appear within quotes or they will be included in the macro stream. The length of a CC command line cannot exceed the maximum length allowed by DCL.
The /NODEFINE and /NOUNDEFINE qualifiers are provided for compatibility with other DCL qualifiers. You can use these qualifiers to cancel /DEFINE or /UNDEFINE qualifiers that you have specified in a symbol that you use to compile Compaq C programs.
The defaults are /NODEFINE and /NOUNDEFINE.
Since the CC command line must be compatible with DCL, the syntax of the /DEFINE and /UNDEFINE qualifiers differs from the syntax of the #define and #undef preprocessor directives in the following way:
$ CC/DEFINE=TRUE #define TRUE 1 |
$ CC/DEFINE=MAYBE=2 #define MAYBE 2 |
$ CC/DEFINE=true #define TRUE 1 |
$
CC/DEFINE="true"
! Preserves lowercase
$
CC/DEFINE="blank=' '"
! Contains and preserves the blank
$
CC/DEFINE="f1=a+b"
! Contains a '+' character
$
CC/DEFINE="funct(a)=2"
! Defines a function-like macro
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$ CC/DEFINE="true=1" #define true 1 |
$ CC/DEFINE="true =1" #define true =1 |
$ CC/DEFINE= TRUE $ CC/DEFINE=(FALSE 0) |
You can pass an equal sign to the compiler in any of the following ways:
$ CC/DEFINE=(EQU==,"equ =","equal==") |
In the first definition, the first equal sign is removed by DCL as the delimiter; the second equal sign is passed to the compiler. In the second example, the space is recognized as a delimiter because the definition is inside quotes; therefore, only one equal sign is required. In the third definition, the first equal sign is recognized as the delimiter and is removed; the second equal sign is passed to the compiler.
You can pass quotation marks in any of the following ways:
$ CC/DEFINE=(QUOTES="""","funct(b)=printf(")")
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In both examples, DCL removes the first and last quotation marks before passing the definition to the compiler.
Here is a simple use of the /UNDEFINE qualifier to cancel a previous definition of TRUE:
$ CC/UNDEFINE=TRUE |
The /UNDEFINE qualifier is useful for undefining the predefined Compaq C preprocessor constants. For example, if you use a preprocessor system identification macro (such as __vaxc , __vaxc , __decc , or __vms ) to conditionally compile segments of Compaq C specific code, you can undefine that constant to see how the portable sections of your program execute. Consider the following program:
main()
{
#if __DECC
printf("I'm being compiled with Compaq C on an OpenVMS system.");
#else
printf("I'm being compiled on some other compiler.");
#endif
}
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This program produces the following output:
$ CC EXAMPLE.C[Return] $ LINK EXAMPLE.OBJ[Return] $ RUN EXAMPLE.EXE[Return] I'm being compiled with Compaq C on an OpenVMS system. $ CC/UNDEFINE="__DECC" EXAMPLE [Return] $ LINK EXAMPLE.OBJ[Return] $ RUN EXAMPLE.EXE[Return] I'm being compiled on some other compiler. |
It controls whether big or little endian ordering of bytes is carried out in character constants. For example, consider the following declaration:
int foo = 'ABCD'; |
Specifying /ENDIAN=LITTLE places 'A' in the first byte, 'B' in the second byte, and so on.
Specifying /ENDIAN=BIG places 'D' in the first byte, 'C' in the second byte, and so on.
The default is /ENDIAN=LITTLE.
The default is /ERROR_LIMIT=30, which specifies that compilation terminates after 31 error messages.
For example, assume the command line contains the following qualifiers:
/EXTERN_MODEL=STRICT_REFDEF="MYDATA"/NOSHARE |
The compiler will behave as if the program begins with the following line:
#pragma extern_model strict_refdef "MYDATA" noshr |
Table 1-7 describes the /EXTERN_MODEL qualifier options.
| Option | Usage |
|---|---|
| COMMON_BLOCK | Sets the compiler's extern_model to the common_block model. This is the model traditionally used for extern data by VAX C. |
| RELAXED_REFDEF |
Sets the compiler's
extern_model
to the
relaxed_refdef
model. Some declarations are references and some are definitions.
Multiple uninitialized definitions for the same object are allowed and
are resolved into one by the linker. However, a reference requires that
at least one definition exist.
This is the model used by the portable C compiler ( pcc ) on UNIX systems. |
| STRICT_REFDEF [=" name"] |
Sets the compiler's
extern_model
to the
strict_refdef
model. Some declarations are references and some are definitions. There
must be exactly one definition in the program for any symbol
referenced. The optional
name, in quotation marks, is the name of the psect for any
definitions.
This is the model specified by ANSI C. Use it in a program that is to be a strict ANSI C conforming program. This model is the preferred alternative to the nonstandard storage-class keywords globaldef and globalref . |
| GLOBALVALUE |
Sets the compiler's
extern_model
to the
globalvalue
model. This model is similar to the
strict_refdef
model except that these global objects have no storage; instead, they
are link-time constant values. There are two cases:
This model is the preferred alternative to the nonstandard storage-class keyword globalvalue . |
The default is /EXTERN_MODEL=RELAXED_REFDEF. This is different from VAX C, which uses the common block model for external objects.
On OpenVMS Alpha systems, representation of double variables defaults to G_floating format if not overridden by another format specified with the /FLOAT or /[NO]G_FLOAT qualifier.
If you are linking against object-module libraries, and /PREFIX=ALL is not specified on the command line:
The VAXCRTLX.OLB, VAXCRTLDX.OLB, and VAXCRTLTX.OLB libraries are used for the same floating-point formats, respectively, but include support for X_FLOAT format (/L_DOUBLE_SIZE=128). (ALPHA ONLY)
If /PREFIX=ALL is specified, then there is no need to link to the above-mentioned *.OLB object libraries. All the symbols you need are in STARLET.OLB. (ALPHA ONLY)
On OpenVMS VAX systems, representation of double variables defaults to D_floating format if not overridden by another format specified with the /FLOAT or /[NO]G_FLOAT qualifier. There is one exception: if /STANDARD=MIA is specified, G_floating is the default. If you are linking against object-module libraries, a program compiled with G_floating format must be linked with the object library DECCRTLG.OLB. (VAX ONLY)
Table 1-8 describes the /FLOAT qualifier options.
| Option | Usage |
|---|---|
| D_FLOAT | double variables are represented in D_floating format. |
| G_FLOAT | double variables are represented in G_floating format. |
| IEEE_FLOAT (ALPHA ONLY) | float and double variables are represented in IEEE floating-point format (S_float and T_float, respectively). Use the /IEEE_MODE qualifier for controlling the handling of IEEE exceptional values. If /IEEE_MODE is not specified, the default behavior is /IEEE_MODE=FAST. |
If you specify /G_FLOAT, double variables are represented in G_floating format.
If you specify /NOG_FLOAT, double variables are represented in D_floating format. (See Section 4.5 for more information on the floating formats.)
On OpenVMS Alpha systems, representation of double variables defaults to G_floating format if not overridden by another format specified with the /FLOAT or /[NO]G_FLOAT qualifier.
If you are linking against object-module libraries, and /PREFIX=ALL is not specified on the command line:
The VAXCRTLX.OLB, VAXCRTLDX.OLB, and VAXCRTLTX.OLB libraries are used for the same floating-point formats, respectively, but include support for X_FLOAT format (/L_DOUBLE_SIZE=128). (ALPHA ONLY)
If /PREFIX=ALL is specified, then there is no need to link to the above-mentioned *.OLB object libraries. All the symbols you need are in STARLET.OLB. (ALPHA ONLY)
On OpenVMS VAX systems, representation of double variables defaults to D_floating format if not overridden by another format specified with the /FLOAT or /[NO]G_FLOAT qualifier. There is one exception: if /STANDARD=MIA is specified, G_floating is the default. If you are linking against object-module libraries, a program compiled with G_floating format must be linked with the object library DECCRTLG.OLB. (VAX ONLY)
Granularity has two aspects: references inside a particular data segment and references between data segments.
The options are:
BYTE
LONGWORD
QUADWORD
The default is /GRANULARITY=QUADWORD.
Table 1-9 describes the /IEEE_MODE options.
| Option | Usage |
|---|---|
| FAST | During program execution, only finite values (no infinities, NaNs, or denorms) are created. Underflows and denormal values are flushed to zero. Exceptional conditions, such as floating-point overflow, divide-by-zero, or use of an IEEE exceptional operand are fatal. This is the default option. |
| UNDERFLOW_TO_ZERO | Generate infinities and NaNs. Flush denormalized results and underflow to zero without exceptions. |
| DENORM_RESULTS | Same as UNDERFLOW_TO_ZERO, except that denorms are generated. |
| INEXACT | Same as DENORM_RESULTS, except that inexact values are trapped. This is the slowest mode, and is not appropriate for any sort of general-purpose computations. |
The default is /IEEE_MODE=FAST.
If one of the places is specified as an empty string, the compiler does not search any of its conventionally-named places:
DECC$USER_INCLUDE
DECC$SYSTEM_INCLUDE
DECC$LIBRARY_INCLUDE
SYS$COMMON:[DECC$LIB.INCLUDE.*]
DECC$TEXT_LIBRARY
SYS$LIBRARY:DECC$RTLDEF.TLB
SYS$LIBRARY:SYS$STARLET_C.TLB
Instead, it searches only places specified explicitly on the command line by the /INCLUDE_DIRECTORY and /LIBRARY qualifiers (or by the location of the primary source file, depending on the /NESTED_INCLUDE_DIRECTORY qualifier). This behavior is similar to that obtained by specifying -I without a directory name to the Tru64 UNIX cc command.
The basic search order depends on the form of the header-file name (after macro expansion). Additional aspects of the search order are controlled by other command-line qualifiers and the presence or absence of logical name definitions.
Only the portable forms of the #include directive are affected by the pathnames specified on an /INCLUDE_DIRECTORY qualifier:
However, an empty string also affects the text-module form specific to OpenVMS systems (example: #include stdio ).
Except where otherwise specified, searching a "place" means that the string designating the place is used as the default file-spec in a call to an RMS system service (for example, $SEARCH/$PARSE). The file-spec consists of the name in the #include directive without enclosing delimiters. The search terminates successfully as soon as a file can be opened for reading.
Prior to OpenVMS VAX Version 7.1, the operating system did not provide a SYS$LIBRARY:SYS$STARLET_C.TLB nor the headers contained therein. Instead, the compiler installation generated these headers and placed them in SYS$LIBRARY:DECC$RTLDEF.TLB. |
For the quoted form of inclusion, the search order is:
For the angle-bracketed form of inclusion, the search order is:
SYS$COMMON:[DECC$LIB.INCLUDE.DECC$RTLDEF].H
SYS$COMMON:[DECC$LIB.INCLUDE.SYS$STARLET_C].H
The compiler installation does not create these directories of header files. Instead, it creates [DECC$LIB.REFERENCE] for your convenience. But if you choose to create and populate SYS$COMMON:[DECC$LIB.INCLUDE.DECC$RTLDEF] or SYS$COMMON:[DECC$LIB.INCLUDE.SYS$STARLET_C].H, the compiler will search them. |
SYS$LIBRARY:DECC$RTLDEF.TLB
SYS$LIBRARY:SYS$STARLET_C.TLB
SYS$LIBRARY:SYS$STARLET_C.TLB
SYS$LIBRARY:.H
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