cc3200: Correct ticks_cpu and ticks_us functions in time module.

cc3200/misc/mpsystick.c

@@ -58,32 +58,14 @@ void sys_tick_wait_at_least(uint32_t start_tick, uint32_t delay_ms) {
 
 // The SysTick timer counts down at HAL_FCPU_HZ, so we can use that knowledge
 // to grab a microsecond counter.
-//
 // We assume that HAL_GetTick returns milliseconds.
 uint32_t sys_tick_get_microseconds(void) {
     mp_uint_t irq_state = disable_irq();
     uint32_t counter = SysTickValueGet();
     uint32_t milliseconds = HAL_GetTick();
-    uint32_t status  = (HWREG(NVIC_ST_CTRL));
     enable_irq(irq_state);
 
-    // It's still possible for the countflag bit to get set if the counter was
-    // reloaded between reading VAL and reading CTRL. With interrupts disabled
-    // it definitely takes less than 50 HCLK cycles between reading VAL and
-    // reading CTRL, so the test (counter > 50) is to cover the case where VAL
-    // is +ve and very close to zero, and the COUNTFLAG bit is also set.
-    if ((status & NVIC_ST_CTRL_COUNT) && counter > 50) {
-        // This means that the HW reloaded VAL between the time we read VAL and the
-        // time we read CTRL, which implies that there is an interrupt pending
-        // to increment the tick counter.
-        milliseconds++;
-    }
-    uint32_t load = (HWREG(NVIC_ST_RELOAD));
+    uint32_t load = SysTickPeriodGet();
     counter = load - counter; // Convert from decrementing to incrementing
-
-    // ((load + 1) / 1000) is the number of counts per microsecond.
-    //
-    // counter / ((load + 1) / 1000) scales from the systick clock to microseconds
-    // and is the same thing as (counter * 1000) / (load + 1)
-    return milliseconds * 1000 + (counter * 1000) / (load + 1);
+    return (milliseconds * 1000) + ((counter * 1000) / load);
 }

cc3200/mods/modutime.c

@@ -150,33 +150,25 @@ STATIC mp_obj_t time_sleep_us (mp_obj_t usec_in) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(time_sleep_us_obj, time_sleep_us);
 
 STATIC mp_obj_t time_ticks_ms(void) {
-    // We want to "cast" the 32 bit unsigned into a small-int.  This means
-    // copying the MSB down 1 bit (extending the sign down), which is
-    // equivalent to just using the MP_OBJ_NEW_SMALL_INT macro.
+    // We want to "cast" the 32 bit unsigned into a 30-bit small-int
     return MP_OBJ_NEW_SMALL_INT(HAL_GetTick() & MP_SMALL_INT_POSITIVE_MASK);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_ms_obj, time_ticks_ms);
 
 STATIC mp_obj_t time_ticks_us(void) {
-    // We want to "cast" the 32 bit unsigned into a small-int.  This means
-    // copying the MSB down 1 bit (extending the sign down), which is
-    // equivalent to just using the MP_OBJ_NEW_SMALL_INT macro.
+    // We want to "cast" the 32 bit unsigned into a 30-bit small-int
     return MP_OBJ_NEW_SMALL_INT(sys_tick_get_microseconds() & MP_SMALL_INT_POSITIVE_MASK);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_us_obj, time_ticks_us);
 
 STATIC mp_obj_t time_ticks_cpu(void) {
-    // We want to "cast" the 32 bit unsigned into a small-int.  This means
-    // copying the MSB down 1 bit (extending the sign down), which is
-    // equivalent to just using the MP_OBJ_NEW_SMALL_INT macro.
-    return MP_OBJ_NEW_SMALL_INT(SysTickValueGet() & MP_SMALL_INT_POSITIVE_MASK);
+    // We want to "cast" the 32 bit unsigned into a 30-bit small-int
+    return MP_OBJ_NEW_SMALL_INT((SysTickPeriodGet() - SysTickValueGet()) & MP_SMALL_INT_POSITIVE_MASK);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_cpu_obj, time_ticks_cpu);
 
 STATIC mp_obj_t time_ticks_diff(mp_obj_t t0, mp_obj_t t1) {
-    // We want to "cast" the 32 bit unsigned into a small-int.  This means
-    // copying the MSB down 1 bit (extending the sign down), which is
-    // equivalent to just using the MP_OBJ_NEW_SMALL_INT macro.
+    // We want to "cast" the 32 bit unsigned into a 30-bit small-int
     uint32_t start = mp_obj_get_int(t0);
     uint32_t end = mp_obj_get_int(t1);
     return MP_OBJ_NEW_SMALL_INT((end - start) & MP_SMALL_INT_POSITIVE_MASK);

tests/wipy/time.py

@@ -70,8 +70,6 @@ print(abs(time.ticks_diff(t1, t2)- 50) <= 1)
 t1 = time.ticks_us()
 time.sleep_us(1000)
 t2 = time.ticks_us()
-print(time.ticks_diff(t1, t2) < 2000)
+print(time.ticks_diff(t1, t2) < 1500)
 
-t1 = time.ticks_cpu()
-t2 = time.ticks_cpu()
-print(time.ticks_diff(t1, t2) >= 0)
+print(time.ticks_diff(time.ticks_cpu(), time.ticks_cpu()) < 16384)