README.DOC File Release notes for the Microsoft(R) FORTRAN Professional Development System, Version 5.1 This document contains release notes for version 5.1 of the Microsoft FORTRAN Professional Development System for MS-DOS(R) and the Microsoft Operating System/2 (MS(R) OS/2). The information in this document is more up-to-date than that in the manuals and the Microsoft Advisor (online help). Microsoft improves its languages documentation at the time of reprinting, so some of the information in this file may already be in your manuals. =================================< Contents >================================== This file has 5 parts: Part Contents ---- -------- 1 The SETUP Program 2 FORTRAN Programming with Microsoft Windows 3 Additions to the Microsoft FORTRAN Reference 4 Additions to the Microsoft FORTRAN Environment and Tools 5 Miscellaneous =============================< The SETUP Program >============================= Disk Space for Additional Libraries ----------------------------------- Each library for a different combination of memory model and floating- point arithmetic requires a minimum of 220K of disk space. If you intend to create more than one library when running SETUP, be sure to take into account the additional disk space required. DECOMP.EXE ---------- The files on the FORTRAN 5.1 disks are compressed. SETUP uses a utility called DECOMP.EXE to decompress the files before copying them to your hard disk. Normally you should use SETUP to copy files, and they will be decompressed automatically. Occasionally, however, you may want to copy a file from the SETUP disks directly to your hard disk without using the SETUP program. In that case, you will have to use the DECOMP.EXE utility to decompress the file. The syntax for DECOMP.EXE is: DECOMP filename.ab$ filename.abc where filename.abc is the decompressed filename. All compressed files end with $. If the filename extension is three characters long, the final character will be replaced with a $. If the extension is two characters, the two characters will be retained and a $ will be placed in the third position. If the extension has one character, then that character will be retained and followed by a $. If there is no extension, then the filename will be given a suffix of a single $. For example: f1.ex$ -> f1.exe source.do$ -> source.doc flib.fd$ -> flib.fd mulmix.c$ -> mulmix.c makefile.$ -> makefile ================< FORTRAN Programming with Microsoft Windows >================ Requirement for Windows Dynamic-Link Libraries ---------------------------------------------- All FORTRAN 5.1 dynamic-link libraries (DLLs) must explicitly export the symbol WEP. To do this, the statement EXPORTS WEP should be added to the DLL's module definition file. The WEP routine is included in the FORTRAN 5.1 startup code. If a DLL already has a user- defined WEP routine (for example, in a mixed-language DLL with existing C code), the WEP routine should be renamed _WEP. The FORTRAN 5.1 startup code will call _WEP, if present, during DLL termination. For additional information concerning the WEP function, see the Windows 3.0 SDK documentation. Close All Files Before Exiting a Windows DLL -------------------------------------------- When a Windows DLL written in FORTRAN terminates, any information left in a file output buffer will be lost. This is a result of how DLLs are terminated in Windows. To insure that all data is written to a file, explicitly CLOSE any open files in a DLL before the DLL is terminated. One way of doing this is by adding a function to the DLL code that closes all files, and calling this function just before the application terminates. MessageBox Support ------------------- FORTRAN supports two modes of MessageBox for QuickWin applications, TASKMODAL and SYSTEMMODAL. TASKMODAL requires that you respond to the message box before the application will perform any further calculations; however, all other applications currently running will not be affected. SYSTEMMODAL requires you to respond before any application may run. Maximizing Windows ------------------ To maximize the frame window of a QuickWin application, place the following statement in the WIN.INI file: [] QWINMaximized=1 where is the base name of your executable file. For example, if the executable file is called PROGRAM.EXE, the value for would be PROGRAM. Windows DLLs and Subprograms with String Arguments -------------------------------------------------- Don't pass char*(*) arguments to a subprogram residing in a Windows DLL. This is because the runtime in the calling DLL or EXE cannot communicate the length of the string with the runtime in the called DLL. ==============< Additions to the Microsoft FORTRAN Reference >================= /Gt option ---------- The /Gt, or data threshold, compiler option can remedy a number of link- time and run-time errors in FORTRAN 5.1. The /Gt option sets a threshold value that determines where data items are stored in memory. Data items that are greater in size than the threshold value, and that would normally be stored in the default data segment, or DGROUP, are moved to a far segment of data. This frees up more room in DGROUP for variables less than the threshold value and for other uses, such as the program STACK and NEAR HEAP. Using the /Gt switch can often help eliminate the LINK errors: L1070: 'segment name':Segment exceeds 64K where segment can be _BSS or _DATA L2041: Stack Plus Data exceeds 64K and the run-time error: F6700: Heap Space Limit Exceeded In each of these cases, too much data is being stored in DGROUP, and using the /Gt switch may free up the required space. See Section 7.6 of the FORTRAN 5.1 Reference for more information. /Oc Option ---------- When you use the /Oc (default common subexpression optimization), the compiler examines only short sections of code for common subexpressions. You can disable default common subexpression optimization with the /Od option. Special Device Names -------------------- The list of special device names in the FORTRAN Reference Manual is incomplete. The complete list of special device names is: Device Name Comments =========== ======== CON stdout, stdin USER stdout, stdin COM1 COM1 port AUX COM1 alias LINE COM1 alias LPT1 stdprn PRN stdprn LPT2 LPT3 LPT4 ERR stderr NUL null device Note that COM2, COM3, and COM4 are not special device names in FORTRAN 5.1. To access these devices, use an OPEN statement of the form: OPEN (10, FILE='lpt1') For connections to LPT2 or COM2, you are also required to specify STATUS='old'. These two devices are not treated as standard devices like LPT1 and COM1. Output to these devices is of the same form as to a file, i.e. the output is buffered and carriage control characters in column 1 are ignored. /ND Option ---------- When using the /ND option in a module, you must also set the loadds attribute on all subprograms called from outside the module. Restrictions on String Assignment --------------------------------- The right and left sides of a string assignment may not reference the same memory location. For example, the following may fail because the generated code overlays the input as it produces the output: character *10 string/'0123456789' string = '#' // string write (*,*) 'string = ' string end IBM VS Extensions in Microsoft FORTRAN ----------------------------------------- Microsoft FORTRAN supports only the following IBM VS FORTRAN extensions: - 31-character names - Allowing integer arrays to contain FORMAT specifications - DO statements without specified labels - DO WHILE statement - END DO statement - Equivalence of character and non character items - Mixing of character and non-character items in COMMON - NAMELIST - Specification of common block items in DATA outside block data subprograms - Initialization on the declaration line - IMPLICIT NONE - INCLUDE - Length specification within declarations - Noninteger array subscripts - Z edit descriptor - ! comments - $ and _ in identifiers $NOTRUNCATE Metacommand ----------------------- $NOTRUNCATE is now the default. As a result, it is possible to create variable names, common block names, and function or subroutine names that are longer than the 26-character space allotted in a .LST file. If these identifiers do not differ in the first 26 characters, the .LST file shows them with the same name. New NINT Functions ------------------ Three NINT intrinsic functions have been added: NINT1, NINT2, and NINT4. These return integer values of one, two, and four bytes respectively. The /4I2 Switch and the INT and NINT Functions ---------------------------------------------- The length of the value returned by the INT and NINT intrinsic functions is determined by the integer storage switch: two bytes if /4I2 is used, four bytes if /4I4 (the default) is used. If you want these functions to return a value with a length different from the length set by the integer storage switch, use INT1, INT2, or INT4 instead of INT, and use NINT1, NINT2, or NINT4 instead of NINT. 80387 Coprocessor Instructions ------------------------------ The run-time libraries recognize the presence of an 80387 coprocessor. If you are not using the alternate math package, the library uses the 80387 SIN and COS instructions, rather than deriving sines and cosines from the FPTAN instruction. Array Conformity in Functions and Subroutines --------------------------------------------- A formal array argument in a subroutine or function does not have to have the same number of dimensions or total size as the actual array argument passed to it. This permits the procedure to contain a formal array that is as large as you think you will ever need; the calling program can then pass any array of the same size or smaller. Note, however, that if the formal and actual dimensions do not match in quantity and size, the formal array elements do not point to the same memory locations as the actual array elements with the same subscripts. In this case, your program has to calculate the correct subscripts. "Out of Memory" Error Message ----------------------------- This compiler error does not have an error number. It occurs when the FL program does not have sufficient memory, as in the following cases: 1. You used wildcard characters to specify the files to be compiled (for example, FL *.FOR) and there were too many files. The exact number of files that can be handled depends on the amount of system memory. 2. The computer did not have enough free memory. This may occur when other processes are running under Microsoft Windows or OS/2. Additional Compiler Error Messages ---------------------------------- F2399: : COMMON (or EQUIVALENCE) : automatic variable illegal. A variable previously declared as AUTOMATIC cannot appear in a COMMON block or an EQUIVALENCE statement. F4187: Debugging information exceeds 64K - extra ignored. There was more debugging information than could fit in the allotted 64K space. The additional information (which is usually symbols) was discarded. Revised Compiler Error Message ------------------------------ The in error message F2384 can be "common block" or "equivalenced," in addition to ALLOCATABLE, EXTERN, FAR, or HUGE. Linker Path Specification ------------------------- The /link option does not allow you to specify the linker's path. FL assumes the linker is in the same directory as the compiler. FL Switch Default Values ------------------------ If no switches appear in the FL command line, the source code is compiled with the following defaults: 1. The Large memory model is used 2. The 8086/8088 instruction set is used 3. 8087/287/387 in-line instructions are used for floating-point calculations 4. Variable, subroutine, or function names are not truncated 5. All integer and single-precision floating-point numbers are four bytes 6. All Microsoft extensions to FORTRAN are enabled 7. FORTRAN 66-style DO statements are disabled 8. Full optimization is performed 9. Debugging (extended run-time error handling) is disabled Any metacommands in a source code file override these defaults. Compiling Extremely Large Programs ---------------------------------- This release contains the file F1L.EXE, which is an alternate form of the Compiler Pass 1 disk if you need it. This compiler pass is used to compile programs that receive error message "F1901: program too large for memory." The F1L.EXE pass is invoked by adding the /B1 option to the FL command line, as follows: FL /B1 F1L.EXE .FOR where is the path (including drive and directory) where F1L.EXE resides, and is the name of the FORTRAN source file you are compiling. Alternatively, you can rename F1L.EXE to F1.EXE to make the high-capacity version the default. Compiler Errors and Warnings Generated by $DEBUG and /4Yb --------------------------------------------------------- In addition to the expanded run-time error handling and testing that $DEBUG and /4Yb enable, there are a number of compiler errors and warnings that appear if $DEBUG or /4Yb are used. They are: Error F2367: INTEGER : range error Error F2533: lower substring bound exceeds upper bound Error F2534: upper substring bound exceeds string length Error F2535: lower substring bound not positive Error F2536: subscript out of range Warning F4501: subscript out of range (array argument) ======< Additions to the Microsoft FORTRAN Environment and Tools >====== Displaying FORTRAN Arrays in CodeView ------------------------------------- CodeView allows you to expand arrays and examine the individual elements of an array. This feature, however, only works on one-dimensional arrays. Arrays of two dimensions or more cannot be expanded in CodeView. Another limitation of CodeView is that it cannot keep track of elements of HUGE arrays beyond the first 64K, or first segment, of the array. An attempt to display an array element beyond the first segment will fail to give the proper value. TXTONLY.OBJ ----------- TXTONLY.OBJ is useful for programs that may use _clearscreen, _outtext, _settextcolor, _settextwindow, and so on, but do not use graphics. If you have a program that never has to work in or switch into graphics modes and never changes the palette, linking TXTONLY.OBJ into your DOS .EXE file (in the .OBJ field) will save about 12K of .EXE size. ================================< Miscellaneous >============================= APPEND.EXE ---------- Do not use the APPEND.EXE utility (shipped with DOS 4.01 and later versions) with FORTRAN applications. FORTRAN 5.1 does not set the APPEND path and the results are unpredictable.