Texas Instruments C28 Series, Student Manual

Page: 330 / 342

Using Pragma
Using Pragma
Pragma is a preprocessor directive that provides directions to the compiler about how to treat a
particular statement. The following example shows how the DATA_SECTION pragma is used
to put a specific buffer into a different section of RAM than other buffers.
The example shows two buffers, bufferA and bufferB. The first buffer, bufferA is treated
normally by the C compiler by placing the buffer (512 words) into the ".bss" section. The second,
bufferB is specifically directed to go into the “my_sect” portion of data memory. Global
variables, normally ".bss", can be redirected as desired.
When using CODE_SECTION, code that is normally linked as ".text", can be identified
otherwise by using the code section pragma (like .sect in assembly).
# # pragma pragma CODE_SECTION ( CODE_SECTION ( func func , ”section name”) , ”section name”)
#
#
pragma
pragma
DATA_SECTION (symbol, “section name”)
DATA_SECTION (symbol, “section name”)
User defined sections from C :
User defined sections from C :
Pragma
Pragma
Examples
Examples
.global _
.global _
bufferA
bufferA
, _
, _
bufferB
bufferB
.
.
bss
bss
_bufferA,512
_bufferA,512
_ _ bufferB bufferB : : . . usect usect “my_sect”,512 “my_sect”,512
Resulting assembly file Resulting assembly file
char bufferA[512];
char bufferA[512];
# # pragma pragma DATA_SECTION( DATA_SECTION( bufferB bufferB , ”my_sect”) , ”my_sect”)
char bufferB[512];
char bufferB[512];
C source file C source file
Example Example - - using the DATA_SECTION using the DATA_SECTION Pragma Pragma
More # More # pragma pragma are defined in the C compiler UG are defined in the C compiler UG
D- 8 C28x – C Programming