Fixed race condition in getticks.

diff --git a/kokare.c b/kokare.c
index 64c3754..8d151df 100644 (file)
--- a/kokare.c
+++ b/kokare.c
@@ -147,9 +147,36 @@ void disphex(unsigned char num)
     dsp[1] = font[num & 0x0f];
 }
 
+/*
+ * This version is used outside interrupts.
+ * It spins until no overflow has happened.
+ */
 unsigned long getticks(void)
 {
-    return(TCNT1 + (((unsigned long)oticks) << 16));
+    uint16_t v;
+    unsigned long r;
+    
+    do {
+       v = oticks;
+       r = TCNT1 + (((unsigned long)oticks) << 16);
+    } while(v != oticks);
+    return(r);
+}
+
+/*
+ * This version is used in interrupts
+ */
+unsigned long getticks2(void)
+{
+    uint16_t v;
+    unsigned long r;
+    
+    v = TCNT1;
+    r = v + (((unsigned long)oticks) << 16);
+    if((TIFR1 & 0x01) && !(v & 0x8000))
+       return(r + 0x10000);
+    else
+       return(r);
 }
 
 void ledcycle(void)
@@ -448,7 +475,7 @@ ISR(SIG_INTERRUPT1)
 {
     unsigned long now;
     
-    now = getticks();
+    now = getticks2();
     if(tstate == 0) {
        tstate = 1;
        if(tlock != 2)