altos: Leave interrupts disabled while checking for task to run

[fw/altos] / src / avr / ao_arch.h

diff --git a/src/avr/ao_arch.h b/src/avr/ao_arch.h
index c82612a8ca12bf98666cc7f2970b147229ca6657..d626e830ee97bf4bdb7bf760ef2832fff698853a 100644 (file)
--- a/src/avr/ao_arch.h
+++ b/src/avr/ao_arch.h
@@ -112,7 +112,6 @@ extern uint8_t      ao_cpu_sleep_disable;
                asm("push r9" "\n\t" "push r8" "\n\t" "push r7" "\n\t" "push r6" "\n\t" "push r5"); \
                asm("push r4" "\n\t" "push r3" "\n\t" "push r2" "\n\t" "push r1" "\n\t" "push r0"); \
                asm("in r0, __SREG__" "\n\t" "push r0");                \
-               sei();                                                  \
        } while (0)
 
 #define ao_arch_save_stack() do {                                      \
@@ -124,16 +123,28 @@ extern uint8_t    ao_cpu_sleep_disable;
 
 #define ao_arch_isr_stack()    /* nothing */
 
-#define ao_arch_cpu_idle() do {                        \
-               if (!ao_cpu_sleep_disable)      \
+/* Idle the CPU (if possible) waiting for an interrupt. Enabling
+ * interrupts and sleeping the CPU must be adjacent to eliminate race
+ * conditions. In all cases, we execute a single nop with interrupts
+ * enabled
+ */
+#define ao_arch_wait_interrupt() do {          \
+               if (!ao_cpu_sleep_disable) {    \
+                       sleep_enable();         \
+                       sei();                  \
                        sleep_cpu();            \
+                       sleep_disable();        \
+               } else {                        \
+                       sei();                  \
+               }                               \
+               ao_arch_nop();                  \
+               cli();                          \
        } while (0)
 
 #define ao_arch_restore_stack() do { \
                uint8_t sp_l, sp_h;                                     \
                sp_l = (uint16_t) ao_cur_task->sp;                      \
                sp_h = ((uint16_t) ao_cur_task->sp) >> 8;               \
-               cli();                                                  \
                asm("out __SP_H__,%0" : : "r" (sp_h) );                 \
                asm("out __SP_L__,%0" : : "r" (sp_l) );                 \
                asm("pop r0"    "\n\t"                                  \