Converters

About Converters

Converters allow Great Cow BASIC to read files that have been created by other programs. A converter can convert these files into Great Cow BASIC libraries or any Great Cow BASIC instruction or a Great Cow BASIC dataset.

A typical use case is when you have a data source file from another computer system and you want to consume the data within your Great Cow BASIC program. The data source file could be database, graphic, reference data or music file. The converter will read these source files and convert them into a format that can be processed by Great Cow BASIC. The conversion process is completed by external application which can be written by the developer or you can use one of the converters provided with the Great Cow BASIC release.

The Great Cow BASIC release includes the converter for BMP files and standard Text files.

With an appropriate Converter installed, and an associated #include to these non-Great Cow BASIC files, Great Cow BASIC will detect that the file extension and hand the processing to the external converting program. When the external converting program had complete, Great Cow BASIC will then continue with the converted source file as a Great Cow BASIC source file.

An example of a converter is to read an existing picture file, convert the picture file to a GCB table and then refer to the picture file table to display the picture file on a GLCD.

Conversion is achieved by including a command within the source program to transform external data. The command used is the instruction #include followed by the data source. An example:

    'Convert ManLooking.BMP to a Great Cow BASIC usable format.

    #include <..\converters\ManLooking.BMP>

The inclusion of the #include line within a Great Cow BASIC program will enable the commencement of the following process:

  1. Great Cow BASIC will examine the ..\converters folder structure for a configuration file that will handle the file extension specified in the include statement.
  2. Great Cow BASIC will examine the configuration file(s) *.INI for command line instructions.
  3. Great Cow BASIC will at stage examine the folder structure for the source file and the target transformed file. If the source file is older than the transformed file the next step will not be executed, goto step 6.
  4. Great Cow BASIC will execute the command as specified within the configuration file to transform the source file to the target file.

    The Conversion program must create the output file extension as specified in the configuration file. If the include statement as an extension of .TXT and the configuration files states the input file extension as .TXT and the output as .GCB the converted file must have the extension of .GCB.

    #include <..\converters\ManLooking.BMP>

    Init file is input file as BMP and output as GCB, then the file expected is ..\converters\ManLooking.GCB

  5. Great Cow BASIC will attempt to include the transformed target file (with the file extension as specified in the configuration file) within the Great Cow BASIC program.
  6. Great Cow BASIC will resume normal processing of the Great Cow BASIC program including the transformed target file, therefore, with normal compiling and errors handling.

For example programs see here.

More about Converters

  1. The configuration file

    The configuration file MUST have the extension of .INI. No leading spaces are permitted in the configuration file. Specification of the configuration file. The file has four items: desc, in, out and exe. Where:

    desc      : Is the description shown in GCGB
    in        : Is the source file extension to be transformed
    out       : Is the target transformed file extension.
    exe       : Is the executable to be run for this specific configuration file.
    params    : Optional, is the required parameter to be passed from the compiler.  Example:  params = %filename% %chipmodel%
    purge     : Optional, will always recreate the target transformed file. The default is to retain the target transformed file unless source has changed.

    You can have multiple configuration files within the ..\converters folder structure.

    Great Cow BASIC will examine all configuration file to match the extension as specified in the #include command.

    Example 1 :

    BMP (Black and White) conversion configuration file is called BMP2GCBasic.ini. The source extension is .bmp, the transformed file extension is .GCB, and the executable is called BMP2GCBASIC.exe.

    desc = BMP file (*.bmp)
    in = bmp
    out = GCB
    exe = BMP2GCBASIC .exe

    An example :

    #include <..\converters\ManLooking.BMP>

    Will be converted by the BMP2GCBASIC .EXE to ..\converters\ManLooking.GCB

    Example 2 :

    Data file conversion configuration file is called TXT2GCB.ini. The source extension is .TXT, the transformed file extension is .GCB, and the command line called AWKRUN.BAT .

    desc = Infrared Patterns (*.txt)
    in = txt
    out = GCB
    exe = awkrun.bat

    An example :

    #include <..\converters\InfraRedPatterns.TXT>

    Will be converted by the AWKRUN.BAT to ..\converters\ InfraRedPatterns.GCB

    The example would require a supporting batch file and a script process to complete the transformation.

  2. Conversion Executable

    The conversion executable may be written in any language (compiled or interpreted).

    The conversion executable MUST create the converted file with the correct file extension as specified in the configuration file.

    The conversion executable will be passed one parameter - the source file name. Using example #1 the conversion executable would be passed ..\converters\ManLooking.BMP

    The conversion executable MUST create a Great Cow BASIC compatible source file. Any valid commands/instruction are permitted.

  3. Installation

    The INI file, the source file and the conversion executable MUST be located in the ..\converters folder. The converters folder is relative to the GCBASIC.EXE compiler folder.

Example 3 : Converter Program

This program converts the InfraRedPatterns.TXT into InfraRedPatterns.GCB that will have a Great Cow BASIC table called DataSource. This example is located in the converter folder of the Great Cow BASIC installation.

  #chip16f877a, 16
  #include <..\converters\InfraRedPatterns.TXT>

  dir portb out

  ' These must be WORDs as this could be large table.
  dim TableReadPosition, TableLen as word

  dir portb out

  ' Read the table length
  TableReadPosition = 0
  ReadTable DataSource, TableReadPosition, TableLen


  Do Forever
      For TableReadPosition = 1 to TableLen step 2
          ReadTable DataSource, TableReadPosition, TransmissionPattern
          ReadTable DataSource, TableReadPosition+1 , PulseDelay
          portb = TransmissionPattern
          wait PulseDelay ms
      next
  Loop

Example 4 : Dynamic Import

This program converts a chip specific configuration file into manifest.GCB that will have a Great Cow BASIC functions called DataIn and DataOut. This example is located in the converter folder of the Great Cow BASIC installation.

    #chip 16f18326

    #include <..\converters\manifest.mcc>

    DataOut ( TX, RA0 )  'this method is created during the convert process. They do not exist withiut the converter.
    DataIn  ( Rx, RC6 )  'this method is created during the convert process. They do not exist withiut the converter.

This example would use the optional parameters of params and purge in the converter configuration file as follows:

    desc = PPS file (*.PPS)
    params = %filename% %chipmodel%
    in = mcc
    out = GCB
    exe = DataHandler.exe
    purge = on