BoostC Explaining Dot H Files

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Draft Not quite Ready


This is my russ_hensel explanation of *.h. Others are welcome to contribute. It is a work in progress, and may or may not be correct.

System.h[edit]

Should almost always be included in all your files. It has limited functionality, largely a bridge to other include files. For the boostC compiler these files are:

  • BoostCPic18.h defines for the 18 series chips
  • BoostCPic16.h defines for the 16 series chips
  • Boostc.h defines and other utility stuff for the compiler.

Apparently the compiler reads the target chip and effectively #defines a value for _PIC16F722 or whatever for the chip that you have designated the target chip.

Links for the macro processor and related

http://publications.gbdirect.co.uk/c_book/chapter2/textual_program_structure.html 2.3. The Textual Structure of Programs

http://publications.gbdirect.co.uk/c_book/chapter7/ 2.3 The Textual Structure of Programs

BoostC.h[edit]

BoostC.h is almost always included, but via System.h, so you may not “see” the include. The following refers to section within BoostC.h, pull up a copy while you are reading this.

Helper macros[edit]

ex:

    #define clear_bit( reg, bitNumb )	((reg) &= ~(1 << (bitNumb)))

These are inline functions using #defines with arguments. ( see [[]] ) many C programmers use these expressions directly in there code, but using clear_bit instead of equivalent is bothe easier to read and write. It make the intent of the program cleared, and may make the code easier to port.


MAKESHORT[edit]

    #define MAKESHORT( dst, lobyte, hibyte )	asm movf _##lobyte, W \
   						asm movwf _##dst \
  						asm movf _##hibyte, W \
      						asm movwf _##dst##+1


Again an inline functions using #define with arguments. There are few other things going on here:

  • using the asm keyword to directly code assembler code
  • using \ to make the multiline macro be read as a single line
  • using ## for Token pasting.


see: 7.3.2.3.Token pasting


with token pasting when

   asm movf _##lobyte, W 

is processed in MAKESORHT( A, B, C ) becomes

   asm movf _B, W 

_B in asm represents the addres of the variable B in the C program.

Additionally from reading this macro we can see that BoostC stores the low byte in low memory and the high byte in higher memory. This is called little-endian. Useful to know if you want to do byte manipulations on multibyte data.

Delay functions generated by linker[edit]

Not quite sure how the linker generates these, but I do understand that the linker needs to know the clock speed to do it. This makes it hard to use precompiled libary functions unless a different one was used for clock speed. Including this allows the compiler to compile what ever call is needed in your C code.


Built-in assembly[edit]

These macros offer a way of using assembler without using the assembler key words _asm or asm. Using asm makes sure that the compiler will not optimize out the code of the macro.

Functions used internally[edit]

look like multibyte arithmitic, not sure how or why, working on it.

More Reading[edit]

see BoostC Inline Functions for more information on inline functions and #define.


Other project Files[edit]

  • .cof binary file, debug information.
  • .stat text file, purpose: Linker Function Resource Usage Dump
  • .obj binary file, source code compiled into object code
  • .lst text assembler code ( no ref to source ) output of xx input to yyy
  • .csam mixed source and assembler code output of xx input to yyy
  • .brws text, symbols etc and their source code reference.
  • tree call tree in text format, display in ide by....