Comtrol eCos - Manual (Page 488)

Chapter 32. µITRON API
(you must have at least one task at startup in order that the system can actually run; this is not so for other uITRON
object types)
Q: Can I have different stack sizes for µITRON tasks?
Simply set aside different amounts of memory for each task to use for its stack. Going back to a typical default
setting for the µITRON tasks, the definitions in
pkgconf/uitron.h might look like this:
#define CYGDAT_UITRON_TASK_EXTERNS \
extern "C" void task1( unsigned int ); \
extern "C" void task2( unsigned int ); \
extern "C" void task3( unsigned int ); \
extern "C" void task4( unsigned int ); \
static char stack1[ CYGNUM_UITRON_STACK_SIZE ], \
stack2[ CYGNUM_UITRON_STACK_SIZE ], \
stack3[ CYGNUM_UITRON_STACK_SIZE ], \
stack4[ CYGNUM_UITRON_STACK_SIZE ];
#define CYGDAT_UITRON_TASK_INITIALIZERS \
CYG_UIT_TASK( "t1", 1, task1, &stack1, CYGNUM_UITRON_STACK_SIZE ), \
CYG_UIT_TASK( "t2", 2, task2, &stack2, CYGNUM_UITRON_STACK_SIZE ), \
CYG_UIT_TASK( "t3", 3, task3, &stack3, CYGNUM_UITRON_STACK_SIZE ), \
CYG_UIT_TASK( "t4", 4, task4, &stack4, CYGNUM_UITRON_STACK_SIZE )
Note that CYGNUM_UITRON_STACK_SIZE is used to control the size of the stack objects themselves, and to tell the
system what size stack is being provided.
Suppose instead stack sizes of 2000, 1000, 800 and 800 were required: this could be achieved by using the GUI
config tool to edit these options, or editting the
.ecc file to get these results in pkgconf/uitron.h :
#define CYGDAT_UITRON_TASK_EXTERNS \
extern "C" void task1( unsigned int ); \
extern "C" void task2( unsigned int ); \
extern "C" void task3( unsigned int ); \
extern "C" void task4( unsigned int ); \
static char stack1[ 2000 ], \
stack2[ 1000 ], \
stack3[ 800 ], \
stack4[ 800 ];
#define CYGDAT_UITRON_TASK_INITIALIZERS \
CYG_UIT_TASK( "t1", 1, task1, &stack1, sizeof( stack1 ) ), \
CYG_UIT_TASK( "t2", 2, task2, &stack2, sizeof( stack2 ) ), \
CYG_UIT_TASK( "t3", 3, task3, &stack3, sizeof( stack3 ) ), \
CYG_UIT_TASK( "t4", 4, task4, &stack4, sizeof( stack4 ) )
Note that the sizeof() operator has been used to tell the system what size stacks are provided, rather than quoting a
number (which is difficult for maintenance) or the symbol
CYGNUM_UITRON_STACK_SIZE (which is wrong).
We recommend using (if available in your release) the stacksize symbols provided in the architectural HAL for your
target, called
CYGNUM_HAL_STACK_SIZE_TYPICAL and CYGNUM_HAL_STACK_SIZE_MINIMUM . So a better (more
portable) version of the above might be:
#define CYGDAT_UITRON_TASK_EXTERNS \
extern "C" void task1( unsigned int ); \
extern "C" void task2( unsigned int ); \
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