QDK PIC24/dsPIC-XC16 - Quantum Leaps

QDK
PIC24/dsPIC-XC16
www.state-machine.com/pic
"and.w w0,#7,w0 \n" \
"mov.w #1,w1 \n" \
"sl w1,w0,w0 \n" \
"ior.b #1,w0 \n" \
"com.b w0,w0 \n" \
"disi #0x3FFF \n" \
"and.b _QK_intNest_" : "=r"(this_sr) : : "w0", "w1"); \
if (QK_intNest_ == 0) { \
uint8_t p = QK_schedPrio_(); \
if (p != (uint8_t)0) { \
__asm__ volatile ("clr.b SR"); \
QK_sched_(p); \
__asm__ volatile ("mov.w %0,SR" : : "r"(this_sr)); \
} \
} \
__asm__ volatile ("disi #0x0000"); \
} while (0);
#include "qk.h" /* QK platform-independent public interface */
(1) The macro QK_ISR() defines the ISR attributes, as required by the XC16 compiler. The macro is
designed to be before the actual ISR signature, as will be illustrated in Listing 8. The argument psv_
controls PSV usage in the ISR and can be either auto_psv or no_auto_psv (see Section 3.3.1).
(2) The macro QK_ISR() then uses the attribute __preprologue__ to define the specific interrupt entry
sequence in assembly, which the compiler copies verbatim before any generated ISR code.
(3) The macro QK_ISR_EXIT() must be invoked as the last instruction of every ISR of IPL 1..6. Again,
the usage of this macro will be illustrated in Listing 8.
4.2 ISRs with the Preemptive QK Kernel
Even though the QK interrupt entry/exit macros are somewhat involved, their use is actually very simple
and enables very straightforward coding ISRs in C, without any need to use assembly. The following
Listing 8 shows how to write ISRs for the preemptive QK kernel:
NOTE: The QK interrupt entry and exit macros QK_ISR() and QK_ISR_EXIT() work only with the
optimization level O1 or higher (O2, O3, or Os) in the XC16 compiler. The MPLABX XC16 compiler
will report a compile-time error “'asm' operand requires impossible reload” when no optimization is
used.
Listing 8: T2Interrupt ISR for QK
(1) QK_ISR(no_auto_psv) _T2Interrupt() {
_T2IF = 0; /* clear Timer 2 interrupt flag */
#ifdef Q_SPY
(2) l_tickTime += BSP_TMR2_PERIOD; /* account for TMR2 overflow */
#endif
QF_TICK(&l_T2Interrupt); /* handle all armed time events in QF */
(3) QK_ISR_EXIT(); /* inform QK about exiting the ISR */
}
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