Use only lower 16bit of lp_ticker as minar clock

In order to create timer overflow faster. Used for
minar testing.

Author: Liyou Zhou

minar-platform/minar_platform_types.h

@@ -27,8 +27,15 @@ namespace platform {
 enum Constants{
     // ticks per second (maximum resolution). This is what the OS works with.
     Time_Base = MINAR_PLATFORM_TIME_BASE,
+
+#if YOTTA_CFG_MINAR_TEST_CLOCK_OVERFLOW
+#warning "testing clock overflow"
+    // use only lower 16bits of timer for testing timer overflow
+	Time_Mask = UINT32_MAX >> 16
+#else
     // 32 bits of time for mbed platforms
     Time_Mask = 0xFFFFFFFFu
+#endif
 };
 
 typedef uint32_t irqstate_t;

source/mbed_platform.cpp

@@ -21,6 +21,10 @@
 #include "mbed-hal/sleep_api.h"
 #include "cmsis-core/core_generic.h"
 
+#if YOTTA_CFG_MINAR_TEST_CLOCK_OVERFLOW
+#include "mbed-drivers/test_env.h"
+#endif
+
 /// @name Local Constants
 const static minar::platform::tick_t Minimum_Sleep = MINAR_PLATFORM_MINIMUM_SLEEP; // in Platform_Time_Base units
 
@@ -53,16 +57,36 @@ void sleep(){
 }
 
 tick_t getTime() {
+#if YOTTA_CFG_MINAR_TEST_CLOCK_OVERFLOW
+    return lp_ticker_read() & Time_Mask;
+#else
     return lp_ticker_read();
+#endif
 }
 
 uint32_t getTimeOverflows(){
     return lp_ticker_get_overflows_counter();
 }
 
 void sleepFromUntil(tick_t now, tick_t until){
+
+#if YOTTA_CFG_MINAR_TEST_CLOCK_OVERFLOW
+    MBED_HOSTTEST_ASSERT(now <= Time_Mask && until <= Time_Mask);
+    tick_t timer_top_bits = lp_ticker_read() & ~Time_Mask;
+    now += timer_top_bits;
+    until += timer_top_bits;
+
+    if (until < now) {
+        until += Time_Mask;
+    }
+
+    const tick_t real_now = timer_top_bits + getTime();
+    //printf("sleepFromUntil %lx %lx real_now %lx\r\n", now, until, real_now);
+#else
     // use real-now for front-most end of do-not-sleep range check
     const tick_t real_now = getTime();
+#endif
+
     if(timeIsInPeriod(now, until, real_now + Minimum_Sleep)){
         // in this case too soon to go to sleep, just return
         return;