Table 45 Nonstandard intrinsic procedures in HP Fortran (continued)

ATANH

FSET

INT4

OR

SYSTEM

 

 

 

 

 

BADDRESS

FSTREAM

INT8

QCOTAN

TAND

 

 

 

 

 

COSD

GETARG

INUM

QCOTAND

TIME

 

 

 

 

 

COTAN

GETENV

IOMSG

QEXT

XOR

 

 

 

 

 

COTAND

GRAN

IQINT

QFLOAT

ZEXT

 

 

 

 

 

DATE

HFIX

IRAND

QNUM

 

 

 

 

 

 

DCMPLX

IACHAR

IRANP

QPROD

 

 

 

 

 

 

DCOTAN

IADDR

ISIGN

RAN

 

HP Fortran also provides nonstandard specific intrinsics that derive from standard generic intrinsics; these nonstandard specific intrinsics are not listed in Table 11-4. They provide generic intrinsics with the ability to operate on nonstandard data type sizes. For example, the generic intrinsic ABS is defined by the Fortran 90 Standard to return the absolute value of the standard data types. HP Fortran provides BABS and ZABS as extensions, enabling ABS to operate on INTEGER(KIND=1) and DOUBLE COMPLEX values—both of which are nonstandard. Many of the nonstandard specific intrinsics (including BABS and ZABS) are compatible with similarly named intrinsics available on other implementations.

Using porting options

HP Fortran provides a number of compile-line options for porting programs. The most important of these is the +langlvl=90option. Compiling your program with this option will cause the compiler to issue warning messages for all nonstandard features.

In addition, HP Fortran includes options that provide compatibility by changing the compiler’s assumptions about the program or by causing the compiler to generate code that executes compatibly with the original implementation. The advantage of using options when porting is that they minimize having to edit and modify source code.

The following sections describe how options can help when porting programs that contain:

•Initialized variables

•Data types that are larger than the default sizes of HP Fortran data types

•Names that clash with HP-specific intrinsics

•Names that end in the underscore character (_)

•One-trip DO loops

•Different formats

•Escape sequences

Uninitialized variables

As noted in “Automatic and static variables” (page 67), the default behavior of HP Fortran is to allocate storage for program variables from the stack. However, older implementations of Fortran often allocate static storage for variables. One of the differences between stack storage and static storage is that static variables are initialized to 0s by the compiler, whereas automatic variables (variables allocated from the stack) must be explicitly initialized by the programmer.

Programs written for implementations of Fortran that allocate static storage by default sometimes rely on the compiler to initialize variables. Compiling and executing such programs on implementations that allocate stack storage can have disastrous results. To make HP Fortran

144 Porting to HP Fortran