Update portables for Microchip AVR Dx and Mega0 (#3)

- Update AVR GCC port files (now the port.c and portmacro.h files are
identical for AVR_Mega0 and AVR_Dx families).
- Add support for low-power tickless mode in portable files for AVR_Dx and
AVR_Mega0.

This change was originally contributed by alexmchp@ in the following PR:
https://github.com/FreeRTOS/FreeRTOS-Kernel/pull/373

6 files changed, 799 insertions, 244 deletions

diff --git a/GCC/AVR_AVRDx/port.c b/GCC/AVR_AVRDx/port.c
index f81af94..fd3e293 100644
--- a/GCC/AVR_AVRDx/port.c
+++ b/GCC/AVR_AVRDx/port.c
@@ -50,119 +50,6 @@ extern volatile RTOS_TCB_t * volatile pxCurrentTCB;
 /*-----------------------------------------------------------*/
 
 /*
- * Macro to save all the general purpose registers, the save the stack pointer
- * into the TCB.
- *
- * The first thing we do is save the flags then disable interrupts.  This is to
- * guard our stack against having a context switch interrupt after we have already
- * pushed the registers onto the stack - causing the 32 registers to be on the
- * stack twice.
- *
- * r1 is set to zero as the compiler expects it to be thus, however some
- * of the math routines make use of R1.
- *
- * The interrupts will have been disabled during the call to portSAVE_CONTEXT()
- * so we need not worry about reading/writing to the stack pointer.
- */
-
-#define portSAVE_CONTEXT()                              \
-    asm volatile ( "push  r0                      \n\t" \
-                   "in    r0, __SREG__            \n\t" \
-                   "cli                           \n\t" \
-                   "push  r0                      \n\t" \
-                   "in    r0, __RAMPZ__           \n\t" \
-                   "push  r0                      \n\t" \
-                   "push  r1                      \n\t" \
-                   "clr   r1                      \n\t" \
-                   "push  r2                      \n\t" \
-                   "push  r3                      \n\t" \
-                   "push  r4                      \n\t" \
-                   "push  r5                      \n\t" \
-                   "push  r6                      \n\t" \
-                   "push  r7                      \n\t" \
-                   "push  r8                      \n\t" \
-                   "push  r9                      \n\t" \
-                   "push  r10                     \n\t" \
-                   "push  r11                     \n\t" \
-                   "push  r12                     \n\t" \
-                   "push  r13                     \n\t" \
-                   "push  r14                     \n\t" \
-                   "push  r15                     \n\t" \
-                   "push  r16                     \n\t" \
-                   "push  r17                     \n\t" \
-                   "push  r18                     \n\t" \
-                   "push  r19                     \n\t" \
-                   "push  r20                     \n\t" \
-                   "push  r21                     \n\t" \
-                   "push  r22                     \n\t" \
-                   "push  r23                     \n\t" \
-                   "push  r24                     \n\t" \
-                   "push  r25                     \n\t" \
-                   "push  r26                     \n\t" \
-                   "push  r27                     \n\t" \
-                   "push  r28                     \n\t" \
-                   "push  r29                     \n\t" \
-                   "push  r30                     \n\t" \
-                   "push  r31                     \n\t" \
-                   "lds   r26, pxCurrentTCB       \n\t" \
-                   "lds   r27, pxCurrentTCB + 1   \n\t" \
-                   "in    r0, __SP_L__            \n\t" \
-                   "st    x+, r0                  \n\t" \
-                   "in    r0, __SP_H__            \n\t" \
-                   "st    x+, r0                  \n\t" );
-
-/*
- * Opposite to portSAVE_CONTEXT().  Interrupts will have been disabled during
- * the context save so we can write to the stack pointer.
- */
-
-#define portRESTORE_CONTEXT()                           \
-    asm volatile ( "lds   r26, pxCurrentTCB       \n\t" \
-                   "lds   r27, pxCurrentTCB + 1   \n\t" \
-                   "ld    r28, x+                 \n\t" \
-                   "out   __SP_L__, r28           \n\t" \
-                   "ld    r29, x+                 \n\t" \
-                   "out   __SP_H__, r29           \n\t" \
-                   "pop   r31                     \n\t" \
-                   "pop   r30                     \n\t" \
-                   "pop   r29                     \n\t" \
-                   "pop   r28                     \n\t" \
-                   "pop   r27                     \n\t" \
-                   "pop   r26                     \n\t" \
-                   "pop   r25                     \n\t" \
-                   "pop   r24                     \n\t" \
-                   "pop   r23                     \n\t" \
-                   "pop   r22                     \n\t" \
-                   "pop   r21                     \n\t" \
-                   "pop   r20                     \n\t" \
-                   "pop   r19                     \n\t" \
-                   "pop   r18                     \n\t" \
-                   "pop   r17                     \n\t" \
-                   "pop   r16                     \n\t" \
-                   "pop   r15                     \n\t" \
-                   "pop   r14                     \n\t" \
-                   "pop   r13                     \n\t" \
-                   "pop   r12                     \n\t" \
-                   "pop   r11                     \n\t" \
-                   "pop   r10                     \n\t" \
-                   "pop   r9                      \n\t" \
-                   "pop   r8                      \n\t" \
-                   "pop   r7                      \n\t" \
-                   "pop   r6                      \n\t" \
-                   "pop   r5                      \n\t" \
-                   "pop   r4                      \n\t" \
-                   "pop   r3                      \n\t" \
-                   "pop   r2                      \n\t" \
-                   "pop   r1                      \n\t" \
-                   "pop   r0                      \n\t" \
-                   "out   __RAMPZ__, r0           \n\t" \
-                   "pop   r0                      \n\t" \
-                   "out   __SREG__, r0            \n\t" \
-                   "pop   r0                      \n\t" );
-
-/*-----------------------------------------------------------*/
-
-/*
  * Perform hardware setup to enable ticks from timer.
  */
 static void prvSetupTimerInterrupt( void );
@@ -206,8 +93,10 @@ StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
     pxTopOfStack--;
     *pxTopOfStack = portFLAGS_INT_ENABLED;
     pxTopOfStack--;
-    *pxTopOfStack = ( StackType_t ) 0x00; /* RAMPZ */
+#if defined(__AVR_HAVE_RAMPZ__)
+    *pxTopOfStack = (StackType_t)0x00; /* RAMPZ */
     pxTopOfStack--;
+#endif
 
     /* Now the remaining registers.   The compiler expects R1 to be 0. */
     *pxTopOfStack = ( StackType_t ) 0x00; /* R1 */
@@ -310,11 +199,15 @@ void vPortYieldFromTick( void )
  */
 static void prvSetupTimerInterrupt( void )
 {
+    /* Configure low-power timer  used in tickless mode */
+#if (configUSE_TICKLESS_IDLE == 1)
+    RTC_INIT();
+#endif
     TICK_init();
 }
 /*-----------------------------------------------------------*/
 
-#if configUSE_PREEMPTION == 1
+#if (configUSE_PREEMPTION == 1)
 
 /*
  * Tick ISR for preemptive scheduler.  We can use a naked attribute as
@@ -344,3 +237,157 @@ static void prvSetupTimerInterrupt( void )
         xTaskIncrementTick();
     }
 #endif /* if configUSE_PREEMPTION == 1 */
+
+#if (configUSE_TICKLESS_IDLE == 1)
+
+volatile uint32_t RTC_OVF_Count = 0;
+
+ISR(RTC_CNT_vect)
+{
+    if (RTC.INTFLAGS & RTC_OVF_bm )
+    {
+        RTC_OVF_Count += 0x00010000;
+        RTC.INTFLAGS = (RTC_OVF_bm);
+    }  
+    
+    if (RTC.INTFLAGS & RTC_CMP_bm )
+    {
+        RTC.INTFLAGS = (RTC_CMP_bm);
+        //Disable compare interrupt
+        RTC.INTCTRL &= (0xFF ^ RTC_CMP_bm);
+    }    
+
+}
+
+static uint32_t ulGetExternalTime(void)
+{
+    uint32_t time_rtc;
+
+    while (RTC.STATUS & RTC_CNTBUSY_bm)
+    {
+        ;
+    }
+    time_rtc = RTC.CNT;
+    time_rtc += RTC_OVF_Count;
+    return time_rtc;
+}
+
+static void vSetWakeTimeInterrupt(uint16_t xExpectedIdleTime)
+{
+    uint32_t rtc_cnt_time;
+
+    /* compute the required  */
+    rtc_cnt_time = RTC_TICKS_TO_COUNTS(xExpectedIdleTime);
+    rtc_cnt_time += ulGetExternalTime();
+
+    while (RTC.STATUS & RTC_CMPBUSY_bm)
+    {
+        ;
+    }
+    RTC.CMP = (rtc_cnt_time & 0xFFFF);
+
+    //Enable compare interrupt
+    RTC.INTCTRL |= RTC_CMP_bm;
+}
+
+/* Define the function that is called by portSUPPRESS_TICKS_AND_SLEEP(). */
+__attribute__((weak)) void vPortSuppressTicksAndSleep(TickType_t xExpectedIdleTime)
+{
+     eSleepModeStatus eSleepStatus;
+     uint32_t ulLowPowerTimeBeforeSleep, ulLowPowerTimeAfterSleep;
+    
+    /* Read the current time from a time source that will remain operational
+    while the microcontroller is in a low power state. */
+    ulLowPowerTimeBeforeSleep = ulGetExternalTime();
+
+    /* Stop the timer that is generating the tick interrupt. */
+    TICK_TMR_STOP();
+
+    /* Enter a critical section that will not effect interrupts bringing the MCU
+    out of sleep mode. */
+    portDISABLE_INTERRUPTS();
+
+    /* Ensure it is still ok to enter the sleep mode. */
+    eSleepStatus = eTaskConfirmSleepModeStatus();
+
+    if (eSleepStatus == eAbortSleep)
+    {
+        /* A task has been moved out of the Blocked state since this macro was
+         * executed, or a context switch is being held pending.  Do not enter a
+         * sleep state.  Restart the tick and exit the critical section. */
+        TICK_TMR_START();
+        portENABLE_INTERRUPTS();
+    }
+    else
+    {
+        if (eSleepStatus == eNoTasksWaitingTimeout)
+        {
+            /* A user definable macro that allows application code to be inserted
+             * here.  Such application code can be used to minimize power consumption
+             * further by turning off IO, peripheral clocks, the Flash, etc. */
+            configPRE_PWR_DOWN_PROCESSING();
+
+            /* There are no running state tasks and no tasks that are blocked with a
+             * time out.  Assuming the application does not care if the tick time slips
+             * with respect to calendar time then enter a deep sleep that can only be
+             * woken by (in this demo case) the user button being pushed on the
+             * Curiosity Nano board.  If the application does require the tick time
+             * to keep better track of the calender time then the PIT peripheral can be
+             * used to make rough adjustments. */
+            portSET_MODE_AND_SLEEP(SLEEP_MODE_PWR_DOWN);
+
+            /* A user definable macro that allows application code to be inserted
+             * here.  Such application code can be used to reverse any actions taken
+             * by the configPRE_STOP_PROCESSING() */
+            configPOST_PWR_DOWN_PROCESSING();
+        }
+        else
+        {
+            /* Configure an interrupt to bring the microcontroller out of its low
+             * power state at the time the kernel next needs to execute.  The
+             * interrupt must be generated from a source that remains operational
+             * when the microcontroller is in a low power state. */
+            vSetWakeTimeInterrupt(xExpectedIdleTime);
+
+            /* Allow the application to define some pre-sleep processing.  This is
+             * the standard configPRE_SLEEP_PROCESSING() macro as described on the
+             * FreeRTOS.org website. */
+            configPRE_SLEEP_PROCESSING(xExpectedIdleTime);
+
+            /* Enter the low power state. */
+            portSET_MODE_AND_SLEEP(SLEEP_MODE_STANDBY);
+
+            /* Determine how long the microcontroller was actually in a low power
+             * state for, which will be less than xExpectedIdleTime if the
+             * microcontroller was brought out of low power mode by an interrupt
+             * other than that configured by the vSetWakeTimeInterrupt() call.
+             * Note that the scheduler is suspended before
+             * portSUPPRESS_TICKS_AND_SLEEP() is called, and resumed when
+             * portSUPPRESS_TICKS_AND_SLEEP() returns.  Therefore no other tasks will
+             * execute until this function completes. */
+            ulLowPowerTimeAfterSleep = ulGetExternalTime();
+
+            /* Allow the application to define some post sleep processing.  This is
+             * the standard configPOST_SLEEP_PROCESSING() macro, as described on the
+             * FreeRTOS.org website. 
+             * It can be used to reverse the actions of configPRE_SLEEP_PROCESSING(), 
+             * and in so doing, return the microcontroller back to its fully operational state */
+            configPOST_SLEEP_PROCESSING(xExpectedIdleTime);
+
+            /* Correct the kernels tick count to account for the time the
+            * microcontroller spent in its low power state. */
+            vTaskStepTick(RTC_COUNTS_TO_TICKS(ulLowPowerTimeAfterSleep - ulLowPowerTimeBeforeSleep));
+            //  vTaskStepTick(xExpectedIdleTime);
+
+        }
+
+        /* Exit the critical section - it might be possible to do this immediately
+         * after the SET_MODE_AND_SLEEP calls. */
+        portENABLE_INTERRUPTS();
+
+        /* Restart the timer that is generating the tick interrupt. */
+        TICK_TMR_START();
+    }
+}
+
+#endif 
diff --git a/GCC/AVR_AVRDx/porthardware.h b/GCC/AVR_AVRDx/porthardware.h
index ca0302e..52e3f12 100644
--- a/GCC/AVR_AVRDx/porthardware.h
+++ b/GCC/AVR_AVRDx/porthardware.h
@@ -55,6 +55,15 @@
         TCB0.INTCTRL = TCB_CAPT_bm;                          \
         TCB0.CTRLA = TCB_ENABLE_bm;                          \
     }
+    
+    #define TICK_TMR_STOP()   TCB0.CTRLA = 0x00;
+    #define TICK_TMR_START()                                 \
+    {                                                        \
+        TCB0.INTFLAGS = TCB_CAPT_bm;                         \
+        TCB0.CTRLA = TCB_ENABLE_bm;                          \
+    }
+    #define TICK_TMR_READ()     TCB0.CNT
+    #define TICK_INT_READY()    (TCB0.INTCTRL & TCB_CAPT_bm)
 
 #elif ( configUSE_TIMER_INSTANCE == 1 )
 
@@ -68,6 +77,15 @@
         TCB1.INTCTRL = TCB_CAPT_bm;                          \
         TCB1.CTRLA = TCB_ENABLE_bm;                          \
     }
+    
+    #define TICK_TMR_STOP()   TCB1.CTRLA = 0x00;
+    #define TICK_TMR_START()                                 \
+    {                                                        \
+        TCB1.INTFLAGS = TCB_CAPT_bm;                         \
+        TCB1.CTRLA = TCB_ENABLE_bm;                          \
+    }
+    #define TICK_TMR_READ()     TCB1.CNT
+    #define TICK_INT_READY()    (TCB1.INTCTRL & TCB_CAPT_bm)
 
 #elif ( configUSE_TIMER_INSTANCE == 2 )
 
@@ -81,6 +99,15 @@
         TCB2.INTCTRL = TCB_CAPT_bm;                          \
         TCB2.CTRLA = TCB_ENABLE_bm;                          \
     }
+    
+    #define TICK_TMR_STOP()   TCB2.CTRLA = 0x00;
+    #define TICK_TMR_START()                                 \
+    {                                                        \
+        TCB2.INTFLAGS = TCB_CAPT_bm;                         \
+        TCB2.CTRLA = TCB_ENABLE_bm;                          \
+    }
+    #define TICK_TMR_READ()     TCB2.CNT
+    #define TICK_INT_READY()    (TCB2.INTCTRL & TCB_CAPT_bm)
 
 #elif ( configUSE_TIMER_INSTANCE == 3 )
 
@@ -94,6 +121,15 @@
         TCB3.INTCTRL = TCB_CAPT_bm;                          \
         TCB3.CTRLA = TCB_ENABLE_bm;                          \
     }
+    
+    #define TICK_TMR_STOP()   TCB3.CTRLA = 0x00;
+    #define TICK_TMR_START()                                 \
+    {                                                        \
+        TCB3.INTFLAGS = TCB_CAPT_bm;                         \
+        TCB3.CTRLA = TCB_ENABLE_bm;                          \
+    }
+    #define TICK_TMR_READ()     TCB3.CNT
+    #define TICK_INT_READY()    (TCB3.INTCTRL & TCB_CAPT_bm)
 
 #elif ( configUSE_TIMER_INSTANCE == 4 )
 
@@ -107,31 +143,79 @@
         TCB4.INTCTRL = TCB_CAPT_bm;                          \
         TCB4.CTRLA = TCB_ENABLE_bm;                          \
     }
+    #define TICK_TMR_STOP()   TCB4.CTRLA = 0x00;
+    #define TICK_TMR_START()                                 \
+    {                                                        \
+        TCB4.INTFLAGS = TCB_CAPT_bm;                         \
+        TCB4.CTRLA = TCB_ENABLE_bm;                          \
+    }
+    #define TICK_TMR_READ()     TCB4.CNT
+    #define TICK_INT_READY()    (TCB4.INTCTRL & TCB_CAPT_bm)
 
 #elif ( configUSE_TIMER_INSTANCE == 5 )
 
-    #define TICK_INT_vect    RTC_CNT_vect
-    #define INT_FLAGS        RTC_INTFLAGS
-    #define INT_MASK         RTC_OVF_bm
-
-/* Hertz to period for RTC setup */
-    #define RTC_PERIOD_HZ( x )    ( 32768 * ( ( 1.0 / x ) ) )
-    #define TICK_init()                                        \
-    {                                                          \
-        while( RTC.STATUS > 0 ) {; }                           \
-        RTC.CTRLA = RTC_PRESCALER_DIV1_gc | 1 << RTC_RTCEN_bp; \
-        RTC.PER = RTC_PERIOD_HZ( configTICK_RATE_HZ );         \
-        RTC.INTCTRL |= 1 << RTC_OVF_bp;                        \
-    }
+    #if ( configUSE_TICKLESS_IDLE == 1 )
+        
+        /* RTC is not supported as tick timer when tickless mode is used */
+        #error Invalid timer setting.
+        
+    #else
+
+        #define TICK_INT_vect    RTC_CNT_vect
+        #define INT_FLAGS        RTC_INTFLAGS
+        #define INT_MASK         RTC_OVF_bm
+
+        /* Hertz to period for RTC setup */
+        #define RTC_PERIOD_HZ( x )    ( 32768 * ( ( 1.0 / x ) ) )
+        #define TICK_init()                                        \
+        {                                                          \
+            while( RTC.STATUS > 0 ) {; }                           \
+            RTC.CTRLA = RTC_PRESCALER_DIV1_gc | 1 << RTC_RTCEN_bp; \
+            RTC.PER = RTC_PERIOD_HZ( configTICK_RATE_HZ );         \
+            RTC.INTCTRL |= 1 << RTC_OVF_bp;                        \
+        }
+        #undef TICK_TMR_STOP()   
+        #undef TICK_TMR_START()  
+        #undef TICK_TMR_READ()     
+        #undef TICK_INT_READY()    
+    #endif
 
 #else /* if ( configUSE_TIMER_INSTANCE == 0 ) */
     #undef TICK_INT_vect
     #undef INT_FLAGS
     #undef INT_MASK
     #undef TICK_init()
+    #undef TICK_TMR_STOP()   
+    #undef TICK_TMR_START()                                    
+    #undef TICK_TMR_READ()     
+    #undef TICK_INT_READY()    
     #error Invalid timer setting.
 #endif /* if ( configUSE_TIMER_INSTANCE == 0 ) */
 
 /*-----------------------------------------------------------*/
 
+
+#if ( configUSE_TICKLESS_IDLE == 1 )
+
+#define LOW_POWER_CLOCK     (32768UL)
+
+#define RTC_TICK_PERIOD_MS            ( ( TickType_t ) 1000 / configTICK_RATE_HZ )
+#define RTC_TICKS_TO_COUNTS(tick_cnt) (uint32_t)(((float)(tick_cnt * LOW_POWER_CLOCK)/configTICK_RATE_HZ) - 0.5)
+#define RTC_COUNTS_TO_TICKS(counts)   (uint32_t)((float)((counts * 1.0) * configTICK_RATE_HZ)/LOW_POWER_CLOCK  )
+
+
+#define RTC_INIT()                                                          \
+{                                                                           \
+    while( RTC.STATUS > 0 ) {; }                                            \
+    RTC.PER = 0xFFFF;                                                       \
+    RTC.CMP = 0x3FFF;                                                       \
+    RTC.CNT = 0;                                                            \
+    RTC.INTFLAGS = RTC_OVF_bm | RTC_CMP_bm;                                 \
+    RTC.CTRLA = RTC_RUNSTDBY_bm | RTC_PRESCALER_DIV1_gc | RTC_RTCEN_bm ;    \
+    RTC.INTCTRL = RTC_OVF_bm | RTC_CMP_bm;                                  \
+}
+
+#endif
+
+ 
 #endif /* PORTHARDWARE_H */
diff --git a/GCC/AVR_AVRDx/portmacro.h b/GCC/AVR_AVRDx/portmacro.h
index f26acca..7879b64 100644
--- a/GCC/AVR_AVRDx/portmacro.h
+++ b/GCC/AVR_AVRDx/portmacro.h
@@ -35,6 +35,7 @@
     #endif
 /* *INDENT-ON* */
 
+#include <avr/sleep.h>
 /*-----------------------------------------------------------
  * Port specific definitions.
  *
@@ -102,6 +103,161 @@ extern void vPortYieldFromISR( void ) __attribute__( ( naked ) );
 #define portTASK_FUNCTION_PROTO( vFunction, pvParameters )    void vFunction( void * pvParameters )
 #define portTASK_FUNCTION( vFunction, pvParameters )          void vFunction( void * pvParameters )
 
+/* Macros for tickless idle/low power functionality. */
+#ifndef portSUPPRESS_TICKS_AND_SLEEP
+
+extern void vPortSuppressTicksAndSleep(TickType_t xExpectedIdleTime);
+#define portSUPPRESS_TICKS_AND_SLEEP(xExpectedIdleTime) vPortSuppressTicksAndSleep(xExpectedIdleTime)
+#endif
+
+#ifndef configPRE_PWR_DOWN_PROCESSING
+#define configPRE_PWR_DOWN_PROCESSING()
+#endif
+
+#ifndef configPOST_PWR_DOWN_PROCESSING
+#define configPOST_PWR_DOWN_PROCESSING()
+#endif
+
+/*-----------------------------------------------------------*/
+
+/* Helper macros for portSAVE_CONTEXT/ portRESTORE_CONTEXT - common support for Mega-0 and AVR-Dx families */
+
+#if defined(__AVR_HAVE_RAMPZ__)
+
+#define portSAVE_RAMPZ()                              \
+    asm volatile("in    r0, __RAMPZ__           \n\t" \
+                 "push  r0                      \n\t");
+
+#define portRESTORE_RAMPZ()                           \
+    asm volatile("pop   r0                      \n\t" \
+                 "out   __RAMPZ__, r0           \n\t");
+
+#else
+
+#define portSAVE_RAMPZ()
+#define portRESTORE_RAMPZ()
+
+#endif
+
+/* Macro to save all the general purpose registers, the save the stack pointer
+ * into the TCB.
+
+ * The first thing we do is save the flags then disable interrupts.  This is to
+ * guard our stack against having a context switch interrupt after we have already
+ * pushed the registers onto the stack - causing the 32 registers to be on the
+ * stack twice.
+
+ * r1 is set to zero as the compiler expects it to be thus, however some
+ * of the math routines make use of R1.
+
+ * The interrupts will have been disabled during the call to portSAVE_CONTEXT()
+ * so we need not worry about reading/writing to the stack pointer. */
+
+#define portSAVE_CONTEXT()                                  \
+    {                                                       \
+        asm volatile("push  r0                      \n\t"   \
+                     "in    r0, __SREG__            \n\t"   \
+                     "cli                           \n\t"   \
+                     "push  r0                      \n\t"); \
+        portSAVE_RAMPZ();                                   \
+        asm volatile("push  r1                      \n\t"   \
+                     "clr   r1                      \n\t"   \
+                     "push  r2                      \n\t"   \
+                     "push  r3                      \n\t"   \
+                     "push  r4                      \n\t"   \
+                     "push  r5                      \n\t"   \
+                     "push  r6                      \n\t"   \
+                     "push  r7                      \n\t"   \
+                     "push  r8                      \n\t"   \
+                     "push  r9                      \n\t"   \
+                     "push  r10                     \n\t"   \
+                     "push  r11                     \n\t"   \
+                     "push  r12                     \n\t"   \
+                     "push  r13                     \n\t"   \
+                     "push  r14                     \n\t"   \
+                     "push  r15                     \n\t"   \
+                     "push  r16                     \n\t"   \
+                     "push  r17                     \n\t"   \
+                     "push  r18                     \n\t"   \
+                     "push  r19                     \n\t"   \
+                     "push  r20                     \n\t"   \
+                     "push  r21                     \n\t"   \
+                     "push  r22                     \n\t"   \
+                     "push  r23                     \n\t"   \
+                     "push  r24                     \n\t"   \
+                     "push  r25                     \n\t"   \
+                     "push  r26                     \n\t"   \
+                     "push  r27                     \n\t"   \
+                     "push  r28                     \n\t"   \
+                     "push  r29                     \n\t"   \
+                     "push  r30                     \n\t"   \
+                     "push  r31                     \n\t"   \
+                     "lds   r26, pxCurrentTCB       \n\t"   \
+                     "lds   r27, pxCurrentTCB + 1   \n\t"   \
+                     "in    r0, __SP_L__            \n\t"   \
+                     "st    x+, r0                  \n\t"   \
+                     "in    r0, __SP_H__            \n\t"   \
+                     "st    x+, r0                  \n\t"); \
+    }
+
+/* Opposite to portSAVE_CONTEXT().  Interrupts will have been disabled during
+ * the context save so we can write to the stack pointer. */
+#define portRESTORE_CONTEXT()                               \
+    {                                                       \
+        asm volatile("lds   r26, pxCurrentTCB       \n\t"   \
+                     "lds   r27, pxCurrentTCB + 1   \n\t"   \
+                     "ld    r28, x+                 \n\t"   \
+                     "out   __SP_L__, r28           \n\t"   \
+                     "ld    r29, x+                 \n\t"   \
+                     "out   __SP_H__, r29           \n\t"   \
+                     "pop   r31                     \n\t"   \
+                     "pop   r30                     \n\t"   \
+                     "pop   r29                     \n\t"   \
+                     "pop   r28                     \n\t"   \
+                     "pop   r27                     \n\t"   \
+                     "pop   r26                     \n\t"   \
+                     "pop   r25                     \n\t"   \
+                     "pop   r24                     \n\t"   \
+                     "pop   r23                     \n\t"   \
+                     "pop   r22                     \n\t"   \
+                     "pop   r21                     \n\t"   \
+                     "pop   r20                     \n\t"   \
+                     "pop   r19                     \n\t"   \
+                     "pop   r18                     \n\t"   \
+                     "pop   r17                     \n\t"   \
+                     "pop   r16                     \n\t"   \
+                     "pop   r15                     \n\t"   \
+                     "pop   r14                     \n\t"   \
+                     "pop   r13                     \n\t"   \
+                     "pop   r12                     \n\t"   \
+                     "pop   r11                     \n\t"   \
+                     "pop   r10                     \n\t"   \
+                     "pop   r9                      \n\t"   \
+                     "pop   r8                      \n\t"   \
+                     "pop   r7                      \n\t"   \
+                     "pop   r6                      \n\t"   \
+                     "pop   r5                      \n\t"   \
+                     "pop   r4                      \n\t"   \
+                     "pop   r3                      \n\t"   \
+                     "pop   r2                      \n\t"   \
+                     "pop   r1                      \n\t"); \
+        portRESTORE_RAMPZ();                                \
+        asm volatile("pop   r0                      \n\t"   \
+                     "out   __SREG__, r0            \n\t"   \
+                     "pop   r0                      \n\t"); \
+    }
+/*-----------------------------------------------------------*/
+
+#define portSET_MODE_AND_SLEEP(mode)  \
+    {                                 \
+        set_sleep_mode(mode);         \
+        sleep_enable();               \
+        portENABLE_INTERRUPTS();      \
+        sleep_cpu();                  \
+        portDISABLE_INTERRUPTS();     \
+        sleep_disable();              \
+    }
+
 /* *INDENT-OFF* */
     #ifdef __cplusplus
         }
diff --git a/GCC/AVR_Mega0/port.c b/GCC/AVR_Mega0/port.c
index 1e25d13..fd3e293 100644
--- a/GCC/AVR_Mega0/port.c
+++ b/GCC/AVR_Mega0/port.c
@@ -50,115 +50,6 @@ extern volatile RTOS_TCB_t * volatile pxCurrentTCB;
 /*-----------------------------------------------------------*/
 
 /*
- * Macro to save all the general purpose registers, the save the stack pointer
- * into the TCB.
- *
- * The first thing we do is save the flags then disable interrupts.  This is to
- * guard our stack against having a context switch interrupt after we have already
- * pushed the registers onto the stack - causing the 32 registers to be on the
- * stack twice.
- *
- * r1 is set to zero as the compiler expects it to be thus, however some
- * of the math routines make use of R1.
- *
- * The interrupts will have been disabled during the call to portSAVE_CONTEXT()
- * so we need not worry about reading/writing to the stack pointer.
- */
-
-#define portSAVE_CONTEXT()                              \
-    asm volatile ( "push  r0                      \n\t" \
-                   "in    r0, __SREG__            \n\t" \
-                   "cli                           \n\t" \
-                   "push  r0                      \n\t" \
-                   "push  r1                      \n\t" \
-                   "clr   r1                      \n\t" \
-                   "push  r2                      \n\t" \
-                   "push  r3                      \n\t" \
-                   "push  r4                      \n\t" \
-                   "push  r5                      \n\t" \
-                   "push  r6                      \n\t" \
-                   "push  r7                      \n\t" \
-                   "push  r8                      \n\t" \
-                   "push  r9                      \n\t" \
-                   "push  r10                     \n\t" \
-                   "push  r11                     \n\t" \
-                   "push  r12                     \n\t" \
-                   "push  r13                     \n\t" \
-                   "push  r14                     \n\t" \
-                   "push  r15                     \n\t" \
-                   "push  r16                     \n\t" \
-                   "push  r17                     \n\t" \
-                   "push  r18                     \n\t" \
-                   "push  r19                     \n\t" \
-                   "push  r20                     \n\t" \
-                   "push  r21                     \n\t" \
-                   "push  r22                     \n\t" \
-                   "push  r23                     \n\t" \
-                   "push  r24                     \n\t" \
-                   "push  r25                     \n\t" \
-                   "push  r26                     \n\t" \
-                   "push  r27                     \n\t" \
-                   "push  r28                     \n\t" \
-                   "push  r29                     \n\t" \
-                   "push  r30                     \n\t" \
-                   "push  r31                     \n\t" \
-                   "lds   r26, pxCurrentTCB       \n\t" \
-                   "lds   r27, pxCurrentTCB + 1   \n\t" \
-                   "in    r0, __SP_L__            \n\t" \
-                   "st    x+, r0                  \n\t" \
-                   "in    r0, __SP_H__            \n\t" \
-                   "st    x+, r0                  \n\t" );
-
-/*
- * Opposite to portSAVE_CONTEXT().  Interrupts will have been disabled during
- * the context save so we can write to the stack pointer.
- */
-
-#define portRESTORE_CONTEXT()                           \
-    asm volatile ( "lds   r26, pxCurrentTCB       \n\t" \
-                   "lds   r27, pxCurrentTCB + 1   \n\t" \
-                   "ld    r28, x+                 \n\t" \
-                   "out   __SP_L__, r28           \n\t" \
-                   "ld    r29, x+                 \n\t" \
-                   "out   __SP_H__, r29           \n\t" \
-                   "pop   r31                     \n\t" \
-                   "pop   r30                     \n\t" \
-                   "pop   r29                     \n\t" \
-                   "pop   r28                     \n\t" \
-                   "pop   r27                     \n\t" \
-                   "pop   r26                     \n\t" \
-                   "pop   r25                     \n\t" \
-                   "pop   r24                     \n\t" \
-                   "pop   r23                     \n\t" \
-                   "pop   r22                     \n\t" \
-                   "pop   r21                     \n\t" \
-                   "pop   r20                     \n\t" \
-                   "pop   r19                     \n\t" \
-                   "pop   r18                     \n\t" \
-                   "pop   r17                     \n\t" \
-                   "pop   r16                     \n\t" \
-                   "pop   r15                     \n\t" \
-                   "pop   r14                     \n\t" \
-                   "pop   r13                     \n\t" \
-                   "pop   r12                     \n\t" \
-                   "pop   r11                     \n\t" \
-                   "pop   r10                     \n\t" \
-                   "pop   r9                      \n\t" \
-                   "pop   r8                      \n\t" \
-                   "pop   r7                      \n\t" \
-                   "pop   r6                      \n\t" \
-                   "pop   r5                      \n\t" \
-                   "pop   r4                      \n\t" \
-                   "pop   r3                      \n\t" \
-                   "pop   r2                      \n\t" \
-                   "pop   r1                      \n\t" \
-                   "pop   r0                      \n\t" \
-                   "out   __SREG__, r0            \n\t" \
-                   "pop   r0                      \n\t" );
-
-/*-----------------------------------------------------------*/
-
-/*
  * Perform hardware setup to enable ticks from timer.
  */
 static void prvSetupTimerInterrupt( void );
@@ -202,6 +93,10 @@ StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
     pxTopOfStack--;
     *pxTopOfStack = portFLAGS_INT_ENABLED;
     pxTopOfStack--;
+#if defined(__AVR_HAVE_RAMPZ__)
+    *pxTopOfStack = (StackType_t)0x00; /* RAMPZ */
+    pxTopOfStack--;
+#endif
 
     /* Now the remaining registers.   The compiler expects R1 to be 0. */
     *pxTopOfStack = ( StackType_t ) 0x00; /* R1 */
@@ -304,11 +199,15 @@ void vPortYieldFromTick( void )
  */
 static void prvSetupTimerInterrupt( void )
 {
+    /* Configure low-power timer  used in tickless mode */
+#if (configUSE_TICKLESS_IDLE == 1)
+    RTC_INIT();
+#endif
     TICK_init();
 }
 /*-----------------------------------------------------------*/
 
-#if configUSE_PREEMPTION == 1
+#if (configUSE_PREEMPTION == 1)
 
 /*
  * Tick ISR for preemptive scheduler.  We can use a naked attribute as
@@ -338,3 +237,157 @@ static void prvSetupTimerInterrupt( void )
         xTaskIncrementTick();
     }
 #endif /* if configUSE_PREEMPTION == 1 */
+
+#if (configUSE_TICKLESS_IDLE == 1)
+
+volatile uint32_t RTC_OVF_Count = 0;
+
+ISR(RTC_CNT_vect)
+{
+    if (RTC.INTFLAGS & RTC_OVF_bm )
+    {
+        RTC_OVF_Count += 0x00010000;
+        RTC.INTFLAGS = (RTC_OVF_bm);
+    }  
+    
+    if (RTC.INTFLAGS & RTC_CMP_bm )
+    {
+        RTC.INTFLAGS = (RTC_CMP_bm);
+        //Disable compare interrupt
+        RTC.INTCTRL &= (0xFF ^ RTC_CMP_bm);
+    }    
+
+}
+
+static uint32_t ulGetExternalTime(void)
+{
+    uint32_t time_rtc;
+
+    while (RTC.STATUS & RTC_CNTBUSY_bm)
+    {
+        ;
+    }
+    time_rtc = RTC.CNT;
+    time_rtc += RTC_OVF_Count;
+    return time_rtc;
+}
+
+static void vSetWakeTimeInterrupt(uint16_t xExpectedIdleTime)
+{
+    uint32_t rtc_cnt_time;
+
+    /* compute the required  */
+    rtc_cnt_time = RTC_TICKS_TO_COUNTS(xExpectedIdleTime);
+    rtc_cnt_time += ulGetExternalTime();
+
+    while (RTC.STATUS & RTC_CMPBUSY_bm)
+    {
+        ;
+    }
+    RTC.CMP = (rtc_cnt_time & 0xFFFF);
+
+    //Enable compare interrupt
+    RTC.INTCTRL |= RTC_CMP_bm;
+}
+
+/* Define the function that is called by portSUPPRESS_TICKS_AND_SLEEP(). */
+__attribute__((weak)) void vPortSuppressTicksAndSleep(TickType_t xExpectedIdleTime)
+{
+     eSleepModeStatus eSleepStatus;
+     uint32_t ulLowPowerTimeBeforeSleep, ulLowPowerTimeAfterSleep;
+    
+    /* Read the current time from a time source that will remain operational
+    while the microcontroller is in a low power state. */
+    ulLowPowerTimeBeforeSleep = ulGetExternalTime();
+
+    /* Stop the timer that is generating the tick interrupt. */
+    TICK_TMR_STOP();
+
+    /* Enter a critical section that will not effect interrupts bringing the MCU
+    out of sleep mode. */
+    portDISABLE_INTERRUPTS();
+
+    /* Ensure it is still ok to enter the sleep mode. */
+    eSleepStatus = eTaskConfirmSleepModeStatus();
+
+    if (eSleepStatus == eAbortSleep)
+    {
+        /* A task has been moved out of the Blocked state since this macro was
+         * executed, or a context switch is being held pending.  Do not enter a
+         * sleep state.  Restart the tick and exit the critical section. */
+        TICK_TMR_START();
+        portENABLE_INTERRUPTS();
+    }
+    else
+    {
+        if (eSleepStatus == eNoTasksWaitingTimeout)
+        {
+            /* A user definable macro that allows application code to be inserted
+             * here.  Such application code can be used to minimize power consumption
+             * further by turning off IO, peripheral clocks, the Flash, etc. */
+            configPRE_PWR_DOWN_PROCESSING();
+
+            /* There are no running state tasks and no tasks that are blocked with a
+             * time out.  Assuming the application does not care if the tick time slips
+             * with respect to calendar time then enter a deep sleep that can only be
+             * woken by (in this demo case) the user button being pushed on the
+             * Curiosity Nano board.  If the application does require the tick time
+             * to keep better track of the calender time then the PIT peripheral can be
+             * used to make rough adjustments. */
+            portSET_MODE_AND_SLEEP(SLEEP_MODE_PWR_DOWN);
+
+            /* A user definable macro that allows application code to be inserted
+             * here.  Such application code can be used to reverse any actions taken
+             * by the configPRE_STOP_PROCESSING() */
+            configPOST_PWR_DOWN_PROCESSING();
+        }
+        else
+        {
+            /* Configure an interrupt to bring the microcontroller out of its low
+             * power state at the time the kernel next needs to execute.  The
+             * interrupt must be generated from a source that remains operational
+             * when the microcontroller is in a low power state. */
+            vSetWakeTimeInterrupt(xExpectedIdleTime);
+
+            /* Allow the application to define some pre-sleep processing.  This is
+             * the standard configPRE_SLEEP_PROCESSING() macro as described on the
+             * FreeRTOS.org website. */
+            configPRE_SLEEP_PROCESSING(xExpectedIdleTime);
+
+            /* Enter the low power state. */
+            portSET_MODE_AND_SLEEP(SLEEP_MODE_STANDBY);
+
+            /* Determine how long the microcontroller was actually in a low power
+             * state for, which will be less than xExpectedIdleTime if the
+             * microcontroller was brought out of low power mode by an interrupt
+             * other than that configured by the vSetWakeTimeInterrupt() call.
+             * Note that the scheduler is suspended before
+             * portSUPPRESS_TICKS_AND_SLEEP() is called, and resumed when
+             * portSUPPRESS_TICKS_AND_SLEEP() returns.  Therefore no other tasks will
+             * execute until this function completes. */
+            ulLowPowerTimeAfterSleep = ulGetExternalTime();
+
+            /* Allow the application to define some post sleep processing.  This is
+             * the standard configPOST_SLEEP_PROCESSING() macro, as described on the
+             * FreeRTOS.org website. 
+             * It can be used to reverse the actions of configPRE_SLEEP_PROCESSING(), 
+             * and in so doing, return the microcontroller back to its fully operational state */
+            configPOST_SLEEP_PROCESSING(xExpectedIdleTime);
+
+            /* Correct the kernels tick count to account for the time the
+            * microcontroller spent in its low power state. */
+            vTaskStepTick(RTC_COUNTS_TO_TICKS(ulLowPowerTimeAfterSleep - ulLowPowerTimeBeforeSleep));
+            //  vTaskStepTick(xExpectedIdleTime);
+
+        }
+
+        /* Exit the critical section - it might be possible to do this immediately
+         * after the SET_MODE_AND_SLEEP calls. */
+        portENABLE_INTERRUPTS();
+
+        /* Restart the timer that is generating the tick interrupt. */
+        TICK_TMR_START();
+    }
+}
+
+#endif 
diff --git a/GCC/AVR_Mega0/porthardware.h b/GCC/AVR_Mega0/porthardware.h
index 758d949..05a04ae 100644
--- a/GCC/AVR_Mega0/porthardware.h
+++ b/GCC/AVR_Mega0/porthardware.h
@@ -55,6 +55,15 @@
         TCB0.INTCTRL = TCB_CAPT_bm;                          \
         TCB0.CTRLA = TCB_ENABLE_bm;                          \
     }
+    
+    #define TICK_TMR_STOP()   TCB0.CTRLA = 0x00;
+    #define TICK_TMR_START()                                 \
+    {                                                        \
+        TCB0.INTFLAGS = TCB_CAPT_bm;                         \
+        TCB0.CTRLA = TCB_ENABLE_bm;                          \
+    }
+    #define TICK_TMR_READ()     TCB0.CNT
+    #define TICK_INT_READY()    (TCB0.INTCTRL & TCB_CAPT_bm)
 
 #elif ( configUSE_TIMER_INSTANCE == 1 )
 
@@ -68,6 +77,15 @@
         TCB1.INTCTRL = TCB_CAPT_bm;                          \
         TCB1.CTRLA = TCB_ENABLE_bm;                          \
     }
+    
+    #define TICK_TMR_STOP()   TCB1.CTRLA = 0x00;
+    #define TICK_TMR_START()                                 \
+    {                                                        \
+        TCB1.INTFLAGS = TCB_CAPT_bm;                         \
+        TCB1.CTRLA = TCB_ENABLE_bm;                          \
+    }
+    #define TICK_TMR_READ()     TCB1.CNT
+    #define TICK_INT_READY()    (TCB1.INTCTRL & TCB_CAPT_bm)
 
 #elif ( configUSE_TIMER_INSTANCE == 2 )
 
@@ -81,6 +99,15 @@
         TCB2.INTCTRL = TCB_CAPT_bm;                          \
         TCB2.CTRLA = TCB_ENABLE_bm;                          \
     }
+    
+    #define TICK_TMR_STOP()   TCB2.CTRLA = 0x00;
+    #define TICK_TMR_START()                                 \
+    {                                                        \
+        TCB2.INTFLAGS = TCB_CAPT_bm;                         \
+        TCB2.CTRLA = TCB_ENABLE_bm;                          \
+    }
+    #define TICK_TMR_READ()     TCB2.CNT
+    #define TICK_INT_READY()    (TCB2.INTCTRL & TCB_CAPT_bm)
 
 #elif ( configUSE_TIMER_INSTANCE == 3 )
 
@@ -94,6 +121,15 @@
         TCB3.INTCTRL = TCB_CAPT_bm;                          \
         TCB3.CTRLA = TCB_ENABLE_bm;                          \
     }
+    
+    #define TICK_TMR_STOP()   TCB3.CTRLA = 0x00;
+    #define TICK_TMR_START()                                 \
+    {                                                        \
+        TCB3.INTFLAGS = TCB_CAPT_bm;                         \
+        TCB3.CTRLA = TCB_ENABLE_bm;                          \
+    }
+    #define TICK_TMR_READ()     TCB3.CNT
+    #define TICK_INT_READY()    (TCB3.INTCTRL & TCB_CAPT_bm)
 
 #elif ( configUSE_TIMER_INSTANCE == 4 )
 
@@ -119,6 +155,29 @@
     #error Invalid timer setting.
 #endif /* if ( configUSE_TIMER_INSTANCE == 0 ) */
 
+
+#if ( configUSE_TICKLESS_IDLE == 1 )
+
+#define LOW_POWER_CLOCK     (32768UL)
+
+#define RTC_TICK_PERIOD_MS            ( ( TickType_t ) 1000 / configTICK_RATE_HZ )
+#define RTC_TICKS_TO_COUNTS(tick_cnt) (uint32_t)(((float)(tick_cnt * LOW_POWER_CLOCK)/configTICK_RATE_HZ) - 0.5)
+#define RTC_COUNTS_TO_TICKS(counts)   (uint32_t)((float)((counts * 1.0) * configTICK_RATE_HZ)/LOW_POWER_CLOCK  )
+
+
+#define RTC_INIT()                                                          \
+{                                                                           \
+	while( RTC.STATUS > 0 ) {; }                                            \
+	RTC.PER = 0xFFFF;                                                       \
+	RTC.CMP = 0x3FFF;                                                       \
+	RTC.CNT = 0;                                                            \
+	RTC.INTFLAGS = RTC_OVF_bm | RTC_CMP_bm;                                 \
+	RTC.CTRLA = RTC_RUNSTDBY_bm | RTC_PRESCALER_DIV1_gc | RTC_RTCEN_bm ;    \
+	RTC.INTCTRL = RTC_OVF_bm | RTC_CMP_bm;                                  \
+}
+
+#endif
+
 /*-----------------------------------------------------------*/
 
 #endif /* PORTHARDWARE_H */
diff --git a/GCC/AVR_Mega0/portmacro.h b/GCC/AVR_Mega0/portmacro.h
index 7d66a73..7879b64 100644
--- a/GCC/AVR_Mega0/portmacro.h
+++ b/GCC/AVR_Mega0/portmacro.h
@@ -30,11 +30,12 @@
 #define PORTMACRO_H
 
 /* *INDENT-OFF* */
-#ifdef __cplusplus
-    extern "C" {
-#endif
+    #ifdef __cplusplus
+        extern "C" {
+    #endif
 /* *INDENT-ON* */
 
+#include <avr/sleep.h>
 /*-----------------------------------------------------------
  * Port specific definitions.
  *
@@ -102,10 +103,165 @@ extern void vPortYieldFromISR( void ) __attribute__( ( naked ) );
 #define portTASK_FUNCTION_PROTO( vFunction, pvParameters )    void vFunction( void * pvParameters )
 #define portTASK_FUNCTION( vFunction, pvParameters )          void vFunction( void * pvParameters )
 
-/* *INDENT-OFF* */
-#ifdef __cplusplus
-    }
+/* Macros for tickless idle/low power functionality. */
+#ifndef portSUPPRESS_TICKS_AND_SLEEP
+
+extern void vPortSuppressTicksAndSleep(TickType_t xExpectedIdleTime);
+#define portSUPPRESS_TICKS_AND_SLEEP(xExpectedIdleTime) vPortSuppressTicksAndSleep(xExpectedIdleTime)
+#endif
+
+#ifndef configPRE_PWR_DOWN_PROCESSING
+#define configPRE_PWR_DOWN_PROCESSING()
+#endif
+
+#ifndef configPOST_PWR_DOWN_PROCESSING
+#define configPOST_PWR_DOWN_PROCESSING()
+#endif
+
+/*-----------------------------------------------------------*/
+
+/* Helper macros for portSAVE_CONTEXT/ portRESTORE_CONTEXT - common support for Mega-0 and AVR-Dx families */
+
+#if defined(__AVR_HAVE_RAMPZ__)
+
+#define portSAVE_RAMPZ()                              \
+    asm volatile("in    r0, __RAMPZ__           \n\t" \
+                 "push  r0                      \n\t");
+
+#define portRESTORE_RAMPZ()                           \
+    asm volatile("pop   r0                      \n\t" \
+                 "out   __RAMPZ__, r0           \n\t");
+
+#else
+
+#define portSAVE_RAMPZ()
+#define portRESTORE_RAMPZ()
+
 #endif
+
+/* Macro to save all the general purpose registers, the save the stack pointer
+ * into the TCB.
+
+ * The first thing we do is save the flags then disable interrupts.  This is to
+ * guard our stack against having a context switch interrupt after we have already
+ * pushed the registers onto the stack - causing the 32 registers to be on the
+ * stack twice.
+
+ * r1 is set to zero as the compiler expects it to be thus, however some
+ * of the math routines make use of R1.
+
+ * The interrupts will have been disabled during the call to portSAVE_CONTEXT()
+ * so we need not worry about reading/writing to the stack pointer. */
+
+#define portSAVE_CONTEXT()                                  \
+    {                                                       \
+        asm volatile("push  r0                      \n\t"   \
+                     "in    r0, __SREG__            \n\t"   \
+                     "cli                           \n\t"   \
+                     "push  r0                      \n\t"); \
+        portSAVE_RAMPZ();                                   \
+        asm volatile("push  r1                      \n\t"   \
+                     "clr   r1                      \n\t"   \
+                     "push  r2                      \n\t"   \
+                     "push  r3                      \n\t"   \
+                     "push  r4                      \n\t"   \
+                     "push  r5                      \n\t"   \
+                     "push  r6                      \n\t"   \
+                     "push  r7                      \n\t"   \
+                     "push  r8                      \n\t"   \
+                     "push  r9                      \n\t"   \
+                     "push  r10                     \n\t"   \
+                     "push  r11                     \n\t"   \
+                     "push  r12                     \n\t"   \
+                     "push  r13                     \n\t"   \
+                     "push  r14                     \n\t"   \
+                     "push  r15                     \n\t"   \
+                     "push  r16                     \n\t"   \
+                     "push  r17                     \n\t"   \
+                     "push  r18                     \n\t"   \
+                     "push  r19                     \n\t"   \
+                     "push  r20                     \n\t"   \
+                     "push  r21                     \n\t"   \
+                     "push  r22                     \n\t"   \
+                     "push  r23                     \n\t"   \
+                     "push  r24                     \n\t"   \
+                     "push  r25                     \n\t"   \
+                     "push  r26                     \n\t"   \
+                     "push  r27                     \n\t"   \
+                     "push  r28                     \n\t"   \
+                     "push  r29                     \n\t"   \
+                     "push  r30                     \n\t"   \
+                     "push  r31                     \n\t"   \
+                     "lds   r26, pxCurrentTCB       \n\t"   \
+                     "lds   r27, pxCurrentTCB + 1   \n\t"   \
+                     "in    r0, __SP_L__            \n\t"   \
+                     "st    x+, r0                  \n\t"   \
+                     "in    r0, __SP_H__            \n\t"   \
+                     "st    x+, r0                  \n\t"); \
+    }
+
+/* Opposite to portSAVE_CONTEXT().  Interrupts will have been disabled during
+ * the context save so we can write to the stack pointer. */
+#define portRESTORE_CONTEXT()                               \
+    {                                                       \
+        asm volatile("lds   r26, pxCurrentTCB       \n\t"   \
+                     "lds   r27, pxCurrentTCB + 1   \n\t"   \
+                     "ld    r28, x+                 \n\t"   \
+                     "out   __SP_L__, r28           \n\t"   \
+                     "ld    r29, x+                 \n\t"   \
+                     "out   __SP_H__, r29           \n\t"   \
+                     "pop   r31                     \n\t"   \
+                     "pop   r30                     \n\t"   \
+                     "pop   r29                     \n\t"   \
+                     "pop   r28                     \n\t"   \
+                     "pop   r27                     \n\t"   \
+                     "pop   r26                     \n\t"   \
+                     "pop   r25                     \n\t"   \
+                     "pop   r24                     \n\t"   \
+                     "pop   r23                     \n\t"   \
+                     "pop   r22                     \n\t"   \
+                     "pop   r21                     \n\t"   \
+                     "pop   r20                     \n\t"   \
+                     "pop   r19                     \n\t"   \
+                     "pop   r18                     \n\t"   \
+                     "pop   r17                     \n\t"   \
+                     "pop   r16                     \n\t"   \
+                     "pop   r15                     \n\t"   \
+                     "pop   r14                     \n\t"   \
+                     "pop   r13                     \n\t"   \
+                     "pop   r12                     \n\t"   \
+                     "pop   r11                     \n\t"   \
+                     "pop   r10                     \n\t"   \
+                     "pop   r9                      \n\t"   \
+                     "pop   r8                      \n\t"   \
+                     "pop   r7                      \n\t"   \
+                     "pop   r6                      \n\t"   \
+                     "pop   r5                      \n\t"   \
+                     "pop   r4                      \n\t"   \
+                     "pop   r3                      \n\t"   \
+                     "pop   r2                      \n\t"   \
+                     "pop   r1                      \n\t"); \
+        portRESTORE_RAMPZ();                                \
+        asm volatile("pop   r0                      \n\t"   \
+                     "out   __SREG__, r0            \n\t"   \
+                     "pop   r0                      \n\t"); \
+    }
+/*-----------------------------------------------------------*/
+
+#define portSET_MODE_AND_SLEEP(mode)  \
+    {                                 \
+        set_sleep_mode(mode);         \
+        sleep_enable();               \
+        portENABLE_INTERRUPTS();      \
+        sleep_cpu();                  \
+        portDISABLE_INTERRUPTS();     \
+        sleep_disable();              \
+    }
+
+/* *INDENT-OFF* */
+    #ifdef __cplusplus
+        }
+    #endif
 /* *INDENT-ON* */
 
 #endif /* PORTMACRO_H */