User`s guide

Implicit DSP/BIOS Instrumentation
3-24
Figure 3-12. Monitoring Stack Pointers (C6000 platform)
For hardware interrupts that are not monitored, there is no overhead—control
passes directly to the HWI function. For interrupts that are monitored, control
first passes to a stub function generated by the Configuration Tool. This
function reads the selected data location, passes the value to the selected
STS operation, and finally branches to the HWI function.
The enable HWI accumulations check box in the RTA Control Panel must be
selected in order for HWI function monitoring to take place. If this type of
tracing is not enabled, the stub function branches to the HWI function without
updating the STS object.
The number of times an interrupt is triggered is recorded in the Count field of
the STS object. When the stack pointer is monitored, the maximum value
reflects the maximum position of the top of the system stack when the
interrupt occurs. This can be useful for determining the system stack size
needed by an application. To determine the maximum depth of the stack,
follow these steps (see Figure 3-13):
1) Using the Configuration Tool right-click on the HWI object and select
Properties, and change the monitor field to Stack Pointer. You should
also change the operation field to STS_add(–*addr) and leave the other
default settings as they are.
These changes give you the minimum value of the stack pointer in the
maximum field of the STS object. This is the top of the stack, since the
stack grows downward in memory.
2) Link your program and use the nmti program, which is described in
Chapter 2, Utility Programs in the TMS320 DSP/BIOS API Reference
Guide for your platform, to find the address of the end of the system
stack. Or, you can find the address in Code Composer by using a
Memory window or the map file to find the address referenced by the
GBL_stackend symbol. (This symbol references the top of the stack.)
IST
00 : b isr
0
20 : b isr
1
20n : b isr
n
isr
0
isr
1
isr
n
IST
00 : b isr
0
20 : b stub
1
20n : b isr
n
isr
0
stub
1
isr
n
isr
1
Default Configuration Monitoring isr
1