Renesas M16C/6N Bedienungsanleitung PDF herunterladen (Seite 13)

QDK™

M16C/Neutrino-NC30

www.state-machine.com/m16c

#include "qep_port.h" /* QEP port */

#include "qvanilla.h" /* "Vanilla" cooperative kernel */

#include "qf.h" /* QF platform-independent public interface */

Listing 3 The qf_port.h header file.

3.2.1 The QF Object Size Configuration

The first part of the

qf_port.h

header file defines limits and sizes of various internal data structures

used in the QF and the applications.

Listing 3(1)

QF_MAX_ACTIVE

defines the maximum number of active objects that QF can manage.

Here this limit is set to just 8, to save some RAM, but you can increase this limit up to 63, in-

clusive.

(2) Maximum event size is set to 2-bytes, meaning that the size of a single event can be up to 64K

bytes.

(3) Maximum event queue counter size is set to 1-byte, meaning that a single event queue can

hold up to 255 events.

(4) Maximum memory pool element size is set to 2-bytes, meaning that a pool can mange blocks

of up to 64K bytes each.

(5) The memory pool counter size is set to 2-bytes, meaning that a pool can manage up to 64K

memory blocks.

(6) The timer counter size is set to 2-bytes, meaning that a maximum timeout can be 2

-1 clock

ticks.

3.2.2 The QF Critical Section

The M16C microcontroller supports interrupt prioritization. Therefore it is safe to unlock interrupts

inside ISRs without running the risk of priority inversions for interrupts. You have full control over

interrupt nesting by configuring the priorities to interrupts. In particular, you can entirely prevent

interrupt nesting by assigning the same priority level to all interrupts.

This means that the simple policy of unconditional unlocking of interrupts upon exit from a critical

section can be used because critical section nesting can be easily and safely avoided (see Chapter

7 of [PSiCC2]). This policy means that you must unlock interrupts inside every ISR before invoking

any QF service, such as

QActive_postFIFIO()

QF_publish()

, or

QF_tick()

The QF critical section policy for M16C is defined in

Listing 3(7-9) as follows:

Listing 3(7) The interrupt lock key is not defined, which means that the interrupt status is not

saved and restored. Just the simple policy of unconditional interrupt locking and unlocking is

used (see Chapter 7 of [PSiCC2]).

(8-9) The macros

QF_INT_LOCK()

QF_INT_UNLOCK()

define the CPU and compiler-specific interrupt

locking mechanism. For the M16C, the inline assembly instruction

FCLR I

clears the global inter-

rupt enable flag. Conversely, the assembly instruction

FSET I

sets the global interrupt enable

flag in the M16C flags register.

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