Renesas M16C/6N Manual do Utilizador descarregar pdf (Página 16)

QDK™

M16C/Neutrino-NC30

www.state-machine.com/m16c

4 The QK Port

The QP port with the preemptive kernel (QK) is remarkably simple and very similar to the “vanilla”

port. In particular, the interrupt locking/unlocking policy is the same, and the BSP is identical, ex-

cept some small additions to the ISRs.

The DPP example for the QK port is provided in the directory

<qp>\examples\m16c\qk\-

nc30\dpp_qk_neutrino

NOTE: QK incurs far less overhead and provides responsiveness exceeding that of any tradi-

tional multiple-stack real-time kernel, at the fraction of the RAM/ROM footprint (see the article

“Build a Super Simple Tasker”, [Samek+ 06]). The non-blocking restrictions of this kernel type

are irrelevant for executing state machines.

4.1 The qk_port.h Header File

In the QK port, you use very similar configuration as the “Vanilla” port described earlier. This sec-

tion describes only the differences, specific to the QK component.

You configure and customize QK through the header file

qk_port.h

, which is located in the QP ports

directory

<qp>\ports\m16c\qk\nc30\

/* interrupt entry code, see NOTE01 */

(1) #define QK_ISR_ENTRY() do { \

(2) ++QK_intNest_; \

(3) _asm("FSET I"); \

} while (0)

/* interrupt exit code, see NOTE01 and NOTE02 */

(4) #define QK_ISR_EXIT() do { \

(5) _asm("LDC #0,FLG"); \

(6) --QK_intNest_; \

(7) if (QK_intNest_ == (uint8_t)0) { \

(8) QK_schedule_(); \

} \

} while (0)

(9) #include "qk.h" /* QK platform-independent public interface */

Listing 6 qk_porth.h header file

(1) The macro

QK_ISR_ENTRY()

is designed to be called upon the entry to an ISR programmed in C.

The macro informs the QK preemptive kernel about entering an interrupt.

(2) The QK interrupt nesting up-down counter

QK_intNest_

is incremented to account for entering a

new interrupt level. This informs the QK scheduler about the interrupt context, so that if a QF

API is called or another interrupt preempts this one, the QK scheduler will not be called.

(3) The interrupts are unlocked.

NOTE: The hardware interrupt entry sequence for M16C includes clearing the global interrupt

enable flag in the FLAGS register, so that interrupts remain locked unless unlocked explicitly.

(4) The macro

QK_ISR_EXIT()

is designed to be called upon the exit from an ISR programmed in C.

The macro informs the QK preemptive kernel about exiting an interrupt.

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