5.4 Building the Example

pic-as -mcpu=16f18446 -Wl,-presetVec=0h -DNUM_TO_READ=100 -Wa,-a -Wl,-Map=linearMemory.map file_1.S file_2.S

In this command, the psect containing the reset code has been linked to address 0. The command also includes the option to generate a map file called linearMemory.map. The -Wa,-a option requests an assembly list file. One list file will be produced for each source module and the above command will generate files called file_1.lst and file_2.lst.

The preprocessor macro NUM_TO_READ, which determines the size of the linear array and the number of values stored, has been defined as 100 using the -D option. Defining this on the command line rather than using #define directives means that the macro can be more easily used in every source file. It also lets you change the value associated with the macro without having to modify your source code.

pic-as -mcpu=16f18446 -Wa,-a -c -DNUM_TO_READ=100 file_1.S
pic-as -mcpu=16f18446 -Wa,-a -c -DNUM_TO_READ=100 file_2.S
pic-as -mcpu=16f18446 -Wl,-presetVec=0h -Wl,-Map=linearMemory.map file_1.o file_2.o

Here, the -c option has been used to generate an intermediate file for each source file. The intermediate (object) files will have a .o extension. The final command links the object files and produces the final output. Note that the option to create the assembly list file is required with the first two assembly commands, as is the -D option that defines the preprocessor macro. The option to create the map files is only needed with the final build command. The -mcpu option, which indicates the target device, must be used with every command.

The MPLAB X IDE performs incremental builds of each source file, in a similar way to the multi-step command-line example, above.

If you are building in the MPLAB X IDE, add additional linker options (such as those specified using the driver option -Wl,linkerOption) to the Custom linker options field in the pic-as Linker > general category in the Project Properties dialog. When adding options to this field, do not include the leading -Wl,, as this prefix is added in by the IDE. Specify additional options to the assembler (such as the -Wa,assemblerOption) in the Additional options field in the pic-as Global Options category (the leading -Wa, must be specified). See Building the Example for screen captures showing where these additional options should be added.

To specify the -D option, enter NUM_TO_READ=100 in the Define preprocessor symbol field in the PIC-AS assembler > Preprocessing and Messages category.