Libraries in Dynamic C

31 March 2016

2000+ line main functions are no fun, but Dynamic C does not make modularization easy. In this post, I’ll document all of the details of using library functions and the problems I’ve encountered using them.

Linking Libraries

The Dynamic C compiler will look for libraries in the directory structure detailed in the file C:\DCRABBIT_XX\LIB.DIR. After a default installation, this file will point towards C:\DCRABBIT_XX\LIB and certain SAMPLES directories. Since C:\DCRABBIT_XX is read-only, I prefer to create a link between the location of my source and the C:\DCRABBIT_XX\LIB directory, rather than either copying the files to this directory or editing the LIB.DIR. On Windows, this can be done using:

mklink C:\DCRabbit_9.62\Lib\starship.lib
C:\Users\catherine\Rabbit3400\lib\starship.lib

This needs to be done as administrator, which can either be done by running the command prompt as administrator, or by using runas:

runas /noprofile /user:pink-beast-windows\catherine "mklink C:\DCRabbit_9
.62\Lib\starship.lib C:\Users\catherine\Rabbit3400\lib\starship.lib"

However, this results in the error:

The system cannot find the file specified.

and my windows-file-system-fu is not strong enough to figure out what I’m doing wrong. Maybe when ubuntu comes to windows 10 I’ll be able to ignore my ignorance.

A Sample Library

The following is an example project in Dynamic C with two libraries. The first library is called starship.lib and contains the source:

/*** BeginHeader StarshipCrew */
struct StarshipCrew{
    char captain[10];
    char first_officer[10];
    char chief_engineer[10];
    char chief_medical_officer[10];
};
/*** EndHeader */

The second library is called starship_functions.lib and contains the source:

/*** BeginHeader assignCaptain */
void assignCaptain(struct StarshipCrew * starship, char * captain);
/*** EndHeader */
void assignCaptain(struct StarshipCrew * starship, char * captain)
{
    sprintf(starship->captain, "%s", captain);
}

And main looks like this:

#use "starship.lib"
#use "starship_functions.lib"

main(){
    struct StarshipCrew enterprise;
    char captain[10];
    sprintf(captain, "Picard");
    assignCaptain(&enterprise, captain);
    printf("Captain of the Enterprise is %s\n", enterprise.captain);
}

This program compiles correctly once the links to the libraries are created in the library directory.

Troubleshooting

Although I’ve just shown you works, there are many, many ways that libraries can be broken, and the compiler messages are not terribly useful.

#use statements do not chain

If you move the #use “starship.lib” line to the starship_functions.lib, the main won’t be able to find the struct definition. The compiler will report the error:

line    5 : ERROR a_starship_test.c   : Struct use before definition.
line    9 : ERROR a_starship_test.c   : ) is missing/expected.
line    9 : ERROR a_starship_test.c   : Invalid struct reference.

Solution

Keep all use statements in your main() file.

Missing BeginHeader statements

Although they look superfluous, the BeginHeader statements are essential. Without the BeginHeader statement on the struct, this will create the error:

line    4 : ERROR a_starship_test.c   : Struct use before definition.
line    8 : ERROR a_starship_test.c   : ) is missing/expected.
line    8 : ERROR a_starship_test.c   : Invalid struct reference.

Without the BeginHeader statement on the function, the error is:

line    7 : WARNING a_starship_test.c   : Reference to 'assignCaptain' has no corresponding prototype.
line    7 : ERROR a_starship_test.c   : Undefined (but used) global label assignCaptain

It is important that the function name matches the function. For example, if the BeginHeader statement is changed to:

/*** BeginHeader assignCap */
void assignCaptain(struct StarshipCrew * starship, char * captain);
/*** EndHeader */

Then the compiler error is:

line    2 : ERROR STARSHIP_FUNCTIONS.LIB   : Undefined (but used) global label assignCaptain

Solution

All structs, typedefs and functions need BeginHeader functionName statement around the prototype, and functionName must match the struct or function name.

Cleaning out compiled libraries

When a program with the #use statement is compiled, the compiler will look for the compiled library files for the used library. These are the files with the extension HX1 and MD1. If it can’t find these files, it will first compile the library, if it does find the files, it will ignore the lib file. This means that if you fix an error in your lib file, the next time you compile your project, you will get the super helpful error of:

line    2 : ERROR STARSHIP_FUNCTIONS.LIB   : Need function definition or declaration.
line    2 : ERROR STARSHIP_FUNCTIONS.LIB   : Syntax error - or garbage at end of program.

Solution

Before compiling your program, delete the HX1 and MD1 files for each library changed.

Order of Import Errors

I’m not sure exactly how to replicate this error, but I have occasionally encountered compiler errors like this:

line  333 : ERROR LCD_FUNCTIONS.LIB   : Redefinition of parameter 1 different.

I’m not sure what causes this, but it typically happens when a library function uses a struct defined in another library, and this library is imported before the library with the function is imported in the main() function.

Solution

I’ve fixed this error by switching the order of imports from:

#use "lcd_functions.lib"
#use "library_with_struct.lib"

to:

#use "library_with_struct.lib"
#use "lcd_functions.lib"
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