Improve efficiency even further. Introduce the configMAX_SYSCALL_INTERRUPT_PRIORITY feature.

Source/portable/IAR/ARM_CM3/port.c

@@ -86,7 +86,7 @@ FreeRTOS.org versions prior to V4.3.0 did not include this definition. */
 
 /* Each task maintains its own interrupt status in the critical nesting
 variable. */
-unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
+static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
 
 /*
  * Setup the timer to generate the tick interrupts.
@@ -119,8 +119,7 @@ portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE
 	*pxTopOfStack = 0;	/* LR */
 	pxTopOfStack -= 5;	/* R12, R3, R2 and R1. */
 	*pxTopOfStack = ( portSTACK_TYPE ) pvParameters;	/* R0 */
-	pxTopOfStack -= 9;	/* R11, R10, R9, R8, R7, R6, R5 and R4. */
+	pxTopOfStack -= 8;	/* R11, R10, R9, R8, R7, R6, R5 and R4. */
-	*pxTopOfStack = 0x00000000; /* uxCriticalNesting. */
 
 	return pxTopOfStack;
 }
@@ -139,6 +138,9 @@ portBASE_TYPE xPortStartScheduler( void )
 	here already. */
 	prvSetupTimerInterrupt();
 	
+	/* Initialise the critical nesting count ready for the first task. */
+	uxCriticalNesting = 0;
+
 	/* Start the first task. */
 	vPortStartFirstTask( *((unsigned portLONG *) 0 ) );
 
@@ -158,10 +160,6 @@ void vPortYieldFromISR( void )
 {
 	/* Set a PendSV to request a context switch. */
 	*(portNVIC_INT_CTRL) |= portNVIC_PENDSVSET;
-
-	/* This function is also called in response to a Yield(), so we want
-	the yield to occur immediately. */
-	portENABLE_INTERRUPTS();
 }
 /*-----------------------------------------------------------*/
 
@@ -184,13 +182,19 @@ void vPortExitCritical( void )
 
 void xPortSysTickHandler( void )
 {
+unsigned portLONG ulDummy;
+
 	/* If using preemption, also force a context switch. */
 	#if configUSE_PREEMPTION == 1
 		*(portNVIC_INT_CTRL) |= portNVIC_PENDSVSET;	
 	#endif
 
+	ulDummy = portSET_INTERRUPT_MASK_FROM_ISR();
+	{
 		vTaskIncrementTick();
 	}
+	portCLEAR_INTERRUPT_MASK_FROM_ISR( ulDummy );
+}
 /*-----------------------------------------------------------*/
 
 /*

Source/portable/IAR/ARM_CM3/portasm.s

@@ -68,7 +68,6 @@ FreeRTOS.org versions prior to V4.3.0 did not include this definition. */
 	thumb
 
 	EXTERN vPortYieldFromISR
-	EXTERN uxCriticalNesting
 	EXTERN pxCurrentTCB
 	EXTERN vTaskSwitchContext
 
@@ -93,36 +92,29 @@ xPortPendSVHandler:
 	ldr	r3, =pxCurrentTCB			/* Get the location of the current TCB. */
 	ldr	r2, [r3]						
 
-	ldr r1, =uxCriticalNesting		/* Save the remaining registers and the critical nesting count onto the task stack. */
+	stmdb r0!, {r4-r11}				/* Save the remaining registers. */
-	ldr r1, [r1]					
-	stmdb r0!, {r1,r4-r11}			
 	str r0, [r2]					/* Save the new top of stack into the first member of the TCB. */
 
 	stmdb sp!, {r3, r14}
+	mov r0, #configMAX_SYSCALL_INTERRUPT_PRIORITY
+	msr basepri, r0
 	bl vTaskSwitchContext			
+	mov r0, #0
+	msr basepri, r0
 	ldmia sp!, {r3, r14}
 
 	ldr r1, [r3]					
-	ldr r2, =uxCriticalNesting	
 	ldr r0, [r1]					/* The first item in pxCurrentTCB is the task top of stack. */
-	ldmia r0!, {r1, r4-r11}			/* Pop the registers and the critical nesting count. */
+	ldmia r0!, {r4-r11}				/* Pop the registers. */
-	str r1, [r2]					/* Save the new critical nesting value into ulCriticalNesting. */
 	msr psp, r0						
-	orr r14, r14, #13			
-
-	cbnz r1, sv_disable_interrupts	/* If the nesting count is greater than 0 we need to exit with interrupts masked. */
 	bx r14							
 
-sv_disable_interrupts:				
-	mov	r1, #configKERNEL_INTERRUPT_PRIORITY
-	msr	basepri, r1
-	bx r14							
 
 /*-----------------------------------------------------------*/
 
 vPortSetInterruptMask:
 	push { r0 }
-	mov R0, #configKERNEL_INTERRUPT_PRIORITY
+	mov R0, #configMAX_SYSCALL_INTERRUPT_PRIORITY
 	msr BASEPRI, R0
 	pop { R0 }
 
@@ -144,9 +136,7 @@ vPortSVCHandler;
 	ldr	r3, =pxCurrentTCB
 	ldr r1, [r3]
 	ldr r0, [r1]
-	ldmia r0!, {r1, r4-r11}
+	ldmia r0!, {r4-r11}
-	ldr r2, =uxCriticalNesting
-	str r1, [r2]
 	msr psp, r0
 	mov r0, #0
 	msr	basepri, r0

Source/portable/IAR/ARM_CM3/portmacro.h

@@ -93,7 +93,7 @@ extern "C" {
 /* Architecture specifics. */
 #define portSTACK_GROWTH			( -1 )
 #define portTICK_RATE_MS			( ( portTickType ) 1000 / configTICK_RATE_HZ )		
-#define portBYTE_ALIGNMENT			4
+#define portBYTE_ALIGNMENT			8
 /*-----------------------------------------------------------*/	
 
 
@@ -117,6 +117,9 @@ extern void vPortClearInterruptMask( void );
 #define portENABLE_INTERRUPTS()					vPortClearInterruptMask();
 #define portENTER_CRITICAL()					vPortEnterCritical()
 #define portEXIT_CRITICAL()						vPortExitCritical()
+#define portSET_INTERRUPT_MASK_FROM_ISR()		0;vPortSetInterruptMask()
+#define portCLEAR_INTERRUPT_MASK_FROM_ISR(x)	vPortClearInterruptMask()
+
 /*-----------------------------------------------------------*/
 
 /* Task function macros as described on the FreeRTOS.org WEB site. */