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authorMarti Bolivar <mbolivar@leaflabs.com>2011-08-03 13:42:30 -0400
committerMarti Bolivar <mbolivar@leaflabs.com>2011-08-03 17:34:03 -0400
commitb33e28fae09fea9e68d71cee3db91c0024b4741f (patch)
tree0f720e25b3bfa71ea549e1b441e2d7ecccb740f6
parent01bbbf344cb56e5aeb43544dc81ed2733f861ca2 (diff)
downloadlibrambutan-b33e28fae09fea9e68d71cee3db91c0024b4741f.tar.gz
librambutan-b33e28fae09fea9e68d71cee3db91c0024b4741f.zip
exti.c: Optimize multiplexed IRQ handlers.
Rewrite existing IRQ handlers in terms of new functions dispatch_single_exti() and dispatch_extis(). dispatch_single_exti() handles EXTIs which have a dedicated IRQ line, and thus doesn't have to check EXTI_PR; it is mostly equivalent to the (now removed) handle_exti(). dispatch_extis() handles multiple EXTIs sharing an IRQ line. Using dispatch_extis() instead of calling handle_exti() multiple times avoids unnecessary I/O to the (volatile) EXTI_BASE->PR register. These changes are in the flavor of the timer IRQ optimizations performed in f5016b15bef56bbdfd187f9b623177ef6dde7ace.
-rw-r--r--libmaple/exti.c91
1 files changed, 48 insertions, 43 deletions
diff --git a/libmaple/exti.c b/libmaple/exti.c
index 74a5d78..ae4d365 100644
--- a/libmaple/exti.c
+++ b/libmaple/exti.c
@@ -29,14 +29,13 @@
* @brief External interrupt control routines
*/
-#include "libmaple.h"
#include "exti.h"
+#include "libmaple.h"
#include "nvic.h"
#include "bitband.h"
-static inline void handle_exti(uint32 exti_num);
-static inline void clear_pending(uint32 exti_num);
-static inline void dispatch_handler(uint32 exti_num);
+static inline void dispatch_single_exti(uint32 exti_num);
+static inline void dispatch_extis(uint32 start, uint32 stop);
/*
* Internal state
@@ -140,74 +139,80 @@ void exti_detach_interrupt(afio_exti_num num) {
*/
void __irq_exti0(void) {
- handle_exti(AFIO_EXTI_0);
+ dispatch_single_exti(AFIO_EXTI_0);
}
void __irq_exti1(void) {
- handle_exti(AFIO_EXTI_1);
+ dispatch_single_exti(AFIO_EXTI_1);
}
void __irq_exti2(void) {
- handle_exti(AFIO_EXTI_2);
+ dispatch_single_exti(AFIO_EXTI_2);
}
void __irq_exti3(void) {
- handle_exti(AFIO_EXTI_3);
+ dispatch_single_exti(AFIO_EXTI_3);
}
void __irq_exti4(void) {
- handle_exti(AFIO_EXTI_4);
+ dispatch_single_exti(AFIO_EXTI_4);
}
void __irq_exti9_5(void) {
- /* Figure out which channel it came from */
- uint32 pending = GET_BITS(EXTI_BASE->PR, 5, 9);
- uint32 i;
-
- /* Dispatch every handler if the pending bit is set */
- for (i = 0; i < 5; i++) {
- if (pending & 0x1) {
- handle_exti(AFIO_EXTI_5 + i);
- }
- pending >>= 1;
- }
+ dispatch_extis(5, 9);
}
void __irq_exti15_10(void) {
- /* Figure out which channel it came from */
- uint32 pending = GET_BITS(EXTI_BASE->PR, 10, 15);
- uint32 i;
-
- /* Dispatch every handler if the pending bit is set */
- for (i = 0; i < 6; i++) {
- if (pending & 0x1) {
- handle_exti(AFIO_EXTI_10 + i);
- }
- pending >>= 1;
- }
+ dispatch_extis(10, 15);
}
/*
* Auxiliary functions
*/
-static inline void handle_exti(uint32 exti) {
- dispatch_handler(exti);
- clear_pending(exti);
- /* If the pending bit is cleared as the last instruction in an ISR,
- * it won't actually be cleared in time and the ISR will fire again.
- * Insert a 2-cycle buffer to allow it to take effect. */
+/* Clear the pending bits for EXTIs whose bits are set in exti_msk.
+ *
+ * If a pending bit is cleared as the last instruction in an ISR, it
+ * won't actually be cleared in time and the ISR will fire again. To
+ * compensate, this function NOPs for 2 cycles after clearing the
+ * pending bits to ensure it takes effect. */
+static inline void clear_pending_msk(uint32 exti_msk) {
+ EXTI_BASE->PR = exti_msk;
asm volatile("nop");
asm volatile("nop");
}
-static inline void dispatch_handler(uint32 exti_num) {
- ASSERT(exti_channels[exti_num].handler);
- if (exti_channels[exti_num].handler) {
- (exti_channels[exti_num].handler)();
+/* This dispatch routine is for non-multiplexed EXTI lines only; i.e.,
+ * it doesn't check EXTI_PR. */
+static inline void dispatch_single_exti(uint32 exti) {
+ voidFuncPtr handler = exti_channels[exti].handler;
+
+ if (!handler) {
+ return;
}
+
+ handler();
+ clear_pending_msk(BIT(exti));
}
-static inline void clear_pending(uint32 exti_num) {
- EXTI_BASE->PR = 1 << exti_num;
+/* Dispatch routine for EXTIs which share an IRQ. */
+static inline void dispatch_extis(uint32 start, uint32 stop) {
+ uint32 pr = EXTI_BASE->PR;
+ uint32 handled_msk = 0;
+ uint32 exti;
+
+ /* Dispatch user handlers for pending EXTIs. */
+ for (exti = start; exti <= stop; exti++) {
+ uint32 eb = BIT(exti);
+ if (pr & eb) {
+ voidFuncPtr handler = exti_channels[exti].handler;
+ if (handler) {
+ handler();
+ handled_msk |= eb;
+ }
+ }
+ }
+
+ /* Clear the pending bits for handled EXTIs. */
+ clear_pending_msk(handled_msk);
}