Performance optimisation.

Source/portable/IAR/ARM_CM3/port.c

@@ -25,11 +25,11 @@
 
 	***************************************************************************
 
-	Please ensure to read the configuration and relevant port sections of the 
+	Please ensure to read the configuration and relevant port sections of the
 	online documentation.
 
 	+++ http://www.FreeRTOS.org +++
-	Documentation, latest information, license and contact details.  
+	Documentation, latest information, license and contact details.
 
 	+++ http://www.SafeRTOS.com +++
 	A version that is certified for use in safety critical systems.
@@ -60,7 +60,6 @@
 #define portNVIC_SYSTICK_LOAD		( ( volatile unsigned portLONG *) 0xe000e014 )
 #define portNVIC_INT_CTRL			( ( volatile unsigned portLONG *) 0xe000ed04 )
 #define portNVIC_SYSPRI2			( ( volatile unsigned portLONG *) 0xe000ed20 )
-#define portNVIC_SYSPRI1			( ( volatile unsigned portLONG *) 0xe000ed1c )
 #define portNVIC_SYSTICK_CLK		0x00000004
 #define portNVIC_SYSTICK_INT		0x00000002
 #define portNVIC_SYSTICK_ENABLE		0x00000001
@@ -88,16 +87,14 @@ unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
 static void prvSetupTimerInterrupt( void );
 
 /*
- * Set the MSP/PSP to a known value.
+ * Exception handlers.
  */
-extern void vSetMSP( unsigned long ulValue );
-extern void vSetPSP( unsigned long ulValue );
+void xPortSysTickHandler( void );
 
 /*
- * Utilities called from the assembler code.
+ * Start first task is a separate function so it can be tested in isolation.
  */
-void vPortSwitchContext( void );
-void vPortIncrementTick( void );
+extern void vPortStartFirstTask( unsigned portLONG ulValue );
 
 /*-----------------------------------------------------------*/
 
@@ -112,7 +109,7 @@ portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE
 	pxTopOfStack--;
 	*pxTopOfStack = ( portSTACK_TYPE ) pxCode;	/* PC */
 	pxTopOfStack--;
-	*pxTopOfStack = 0xfffffffd;	/* LR */
+	*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. */
@@ -136,12 +133,7 @@ portBASE_TYPE xPortStartScheduler( void )
 	prvSetupTimerInterrupt();
 	
 	/* Start the first task. */
-	vSetPSP( 0 );
-	vSetMSP( *((unsigned portLONG *) 0 ) );
-	*(portNVIC_INT_CTRL) |= portNVIC_PENDSVSET;
-
-	/* Enable interrupts */
-	portENABLE_INTERRUPTS();
+	vPortStartFirstTask( *((unsigned portLONG *) 0 ) );
 
 	/* Should not get here! */
 	return 0;
@@ -183,6 +175,16 @@ void vPortExitCritical( void )
 }
 /*-----------------------------------------------------------*/
 
+void xPortSysTickHandler( void )
+{
+	vTaskIncrementTick();
+	
+	/* If using preemption, also force a context switch. */
+	#if configUSE_PREEMPTION == 1
+		*(portNVIC_INT_CTRL) |= portNVIC_PENDSVSET;	
+	#endif
+}
+/*-----------------------------------------------------------*/
 
 /*
  * Setup the systick timer to generate the tick interrupts at the required
@@ -196,19 +198,3 @@ void prvSetupTimerInterrupt( void )
 }
 /*-----------------------------------------------------------*/
 
-void vPortSwitchContext( void )
-{
-	vPortSetInterruptMask();
-	vTaskSwitchContext();
-	vPortClearInterruptMask();
-}
-/*-----------------------------------------------------------*/
-
-void vPortIncrementTick( void )
-{
-	vPortSetInterruptMask();
-	vTaskIncrementTick();
-	vPortClearInterruptMask();
-}
-
-

Source/portable/IAR/ARM_CM3/portasm.s

@@ -25,11 +25,11 @@
 
 	***************************************************************************
 
-	Please ensure to read the configuration and relevant port sections of the 
+	Please ensure to read the configuration and relevant port sections of the
 	online documentation.
 
 	+++ http://www.FreeRTOS.org +++
-	Documentation, latest information, license and contact details.  
+	Documentation, latest information, license and contact details.
 
 	+++ http://www.SafeRTOS.com +++
 	A version that is certified for use in safety critical systems.
@@ -61,23 +61,18 @@ FreeRTOS.org versions prior to V4.3.0 did not include this definition. */
 	thumb
 
 	EXTERN vPortYieldFromISR
-	EXTERN vPortSwitchContext
-	EXTERN vPortIncrementTick
 	EXTERN uxCriticalNesting
 	EXTERN pxCurrentTCB
+	EXTERN vTaskSwitchContext
 
-	PUBLIC vSetPSP
 	PUBLIC vSetMSP
 	PUBLIC xPortPendSVHandler
-	PUBLIC xPortSysTickHandler
 	PUBLIC vPortSetInterruptMask
 	PUBLIC vPortClearInterruptMask
+	PUBLIC vPortSVCHandler
+	PUBLIC vPortStartFirstTask
 
 
-vSetPSP:
-	msr psp, r0
-	bx lr
-	
 /*-----------------------------------------------------------*/
 
 vSetMSP
@@ -88,67 +83,34 @@ vSetMSP
 
 xPortPendSVHandler:
 	mrs r0, psp						
-	cbz r0, no_save					
-	/* Save the context into the TCB. */
-	stmdb r0!, {r4-r11}				
-	sub r0, r0, #0x04					
-	ldr r1, =uxCriticalNesting
-	ldr r2, =pxCurrentTCB		
-	ldr r1, [r1]					
-	ldr r2, [r2]					
-	str r1, [r0]					
-	str r0, [r2]					
-									
-no_save:
-	push {r14}						
-	bl vPortSwitchContext			
-	pop {r14}						
-	/* Restore the context. */		
-	ldr r1, =pxCurrentTCB
+	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. */
 	ldr r1, [r1]					
-	ldr r0, [r1]					
-	ldmia r0!, {r1, r4-r11}			
-	ldr r2, =uxCriticalNesting
-	str r1, [r2]					
+	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}			
+	bl vTaskSwitchContext			
+	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. */
+	str r1, [r2]					/* Save the new critical nesting value into ulCriticalNesting. */
 	msr psp, r0						
-	orr r14, r14, #0xd					
-	/* Exit with interrupts in the state required by the task. */
-	cbnz r1, sv_disable_interrupts	
+	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
+	msr	basepri, r1
 	bx r14							
 
-
-/*-----------------------------------------------------------*/
-
-xPortSysTickHandler:
-	/* Call the scheduler tick function. */
-	push {r14}
-	bl vPortIncrementTick
-	pop {r14}
-	
-	/* If using preemption, also force a context switch. */
-	#if configUSE_PREEMPTION == 1
-		push {r14}
-		bl vPortYieldFromISR
-		pop {r14}
-	#endif
-
-	/* Exit with interrupts in the correct state. */
-    ldr r2, =uxCriticalNesting
-	ldr r2, [r2]
-	cbnz r2, tick_disable_interrupts
-	bx r14
-
-tick_disable_interrupts:
-	mov	r1, #configKERNEL_INTERRUPT_PRIORITY
-	msr	basepri, R1
-	
-	bx r14
-
 /*-----------------------------------------------------------*/
 
 vPortSetInterruptMask:
@@ -171,5 +133,23 @@ vPortClearInterruptMask:
 
 /*-----------------------------------------------------------*/
 
+vPortSVCHandler;
+	ldr	r3, =pxCurrentTCB
+	ldr r1, [r3]
+	ldr r0, [r1]
+	ldmia r0!, {r1, r4-r11}
+	ldr r2, =uxCriticalNesting
+	str r1, [r2]
+	msr psp, r0
+	orr r14, r14, #13
+	bx r14
+
+/*-----------------------------------------------------------*/
+
+vPortStartFirstTask
+	msr msp, r0
+	svc 0
+
+
 	END