Coding Notes

The following are the coding notes when porting from CodeWarrior to GCC.

1. User-defined sections declaration:
   • CodeWarrior

      __declspec(section ".foo") void foo();

   • GCC

      __attribute__((section(".foo"))) void foo();

2. GCC does not support the use of variable for global array initialization. However, this support is available in CodeWarrior.
   • CodeWarrior

     const int var=5;

     int arr[var] = {1,2,3,4,var}; // error on gcc

   • GCC

     int arr[5] = {1,2,3,4,5};

3. GCC does not support the use of variable for constant initialization. However, this support is available in CodeWarrior.
   • CodeWarrior

     const int var=1;

     const int var2 = var;

   • GCC

     const int var2 = 1;

4. -n option should be passed to gcc linker.

   The program segment gets aligned to its page size which is 0x8000 by default.

   This can be removed by -n option. This will disable the page alignment and use the section alignment on program segment.

5. -fextended- identifiers are used in GCC to accept universal characters. However, in CodeWarrior universal characters are accepted by default.
6. Changes required in porting CW assembly .s files to GCC syntax:
   1. Use .global instead of .public.
   2. Comments to begin with @.
   3. Put .syntax unified near the start of your assembly source. This turns on Unified Assembly Language, which is required to get all the features of Thumb-2.
   4. sreg01 .textequ "r1" change to #define sreg01 r1.
   5. Use option -mimplicit-it=always.