replace 0x10000 with max_count constant, and handle a couple more

corner cases

diff --git a/comedi/drivers/8253.h b/comedi/drivers/8253.h
index 12f9ae449aa31fe3e2ee313ca7ac21619610b96c..90804db5fd83a7b98a457c4c23acba8b3d29149a 100644 (file)
--- a/comedi/drivers/8253.h
+++ b/comedi/drivers/8253.h
@@ -116,7 +116,6 @@ static inline void i8253_cascade_ns_to_timer_power(int i8253_osc_base, unsigned
        *d2 = div2 & 0xffff;
 }
 
-
 static inline void i8253_cascade_ns_to_timer_2div(int i8253_osc_base,
        unsigned int *d1, unsigned int *d2, unsigned int *nanosec, int round_mode)
 {
@@ -127,16 +126,16 @@ static inline void i8253_cascade_ns_to_timer_2div(int i8253_osc_base,
        unsigned int ns;
        unsigned int start;
        unsigned int ns_low, ns_high;
-
+       static const unsigned int max_count = 0x10000;
        /* exit early if everything is already correct (this can save time
         * since this function may be called repeatedly during command tests
         * and execution) */
-       div1 = *d1 ? *d1 : 0x10000;
-       div2 = *d2 ? *d2 : 0x10000;
+       div1 = *d1 ? *d1 : max_count;
+       div2 = *d2 ? *d2 : max_count;
        divider = div1 * div2;
        if(div1 * div2 * i8253_osc_base == *nanosec &&
-               div1 > 1 && div1 <= 0x10000 &&
-               div2 > 1 && div2 <= 0x10000 &&
+               div1 > 1 && div1 <= max_count &&
+               div2 > 1 && div2 <= max_count &&
                /* check for overflow */
                divider > div1 && divider > div2 &&
                divider * i8253_osc_base > divider &&
@@ -153,23 +152,21 @@ static inline void i8253_cascade_ns_to_timer_2div(int i8253_osc_base,
        ns_glb = 0;
        ns_lub = 0xffffffff;
 
-       div2 = 0x10000;
+       div2 = max_count;
        start = divider / div2;
        if(start < 2) start = 2;
-       for (div1 = start; div1 <= divider / div1 + 1; div1++) {
-               for(div2 = divider / div1; div1 * div2 <= divider + div1 + 1; div2++) {
+       for (div1 = start; div1 <= divider / div1 + 1 && div1 <= max_count; div1++) {
+               for(div2 = divider / div1; div1 * div2 <= divider + div1 + 1 && div2 <= max_count; div2++) {
                        ns = i8253_osc_base * div1 * div2;
                        if (ns <= *nanosec && ns > ns_glb) {
                                ns_glb = ns;
                                div1_glb = div1;
                                div2_glb = div2;
                        }
-                       if (div2 <= 0x10000) {
-                               if (ns >= *nanosec && ns < ns_lub) {
-                                       ns_lub = ns;
-                                       div1_lub = div1;
-                                       div2_lub = div2;
-                               }
+                       if (ns >= *nanosec && ns < ns_lub) {
+                               ns_lub = ns;
+                               div1_lub = div1;
+                               div2_lub = div2;
                        }
                }
        }