Merge branch 'freertos'

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diff --git a/libraries/FreeRTOS/utility/port.c b/libraries/FreeRTOS/utility/port.c
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+/*
+    FreeRTOS V7.0.1 - Copyright (C) 2011 Real Time Engineers Ltd.
+	
+
+    ***************************************************************************
+     *                                                                       *
+     *    FreeRTOS tutorial books are available in pdf and paperback.        *
+     *    Complete, revised, and edited pdf reference manuals are also       *
+     *    available.                                                         *
+     *                                                                       *
+     *    Purchasing FreeRTOS documentation will not only help you, by       *
+     *    ensuring you get running as quickly as possible and with an        *
+     *    in-depth knowledge of how to use FreeRTOS, it will also help       *
+     *    the FreeRTOS project to continue with its mission of providing     *
+     *    professional grade, cross platform, de facto standard solutions    *
+     *    for microcontrollers - completely free of charge!                  *
+     *                                                                       *
+     *    >>> See http://www.FreeRTOS.org/Documentation for details. <<<     *
+     *                                                                       *
+     *    Thank you for using FreeRTOS, and thank you for your support!      *
+     *                                                                       *
+    ***************************************************************************
+
+
+    This file is part of the FreeRTOS distribution.
+
+    FreeRTOS is free software; you can redistribute it and/or modify it under
+    the terms of the GNU General Public License (version 2) as published by the
+    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
+    >>>NOTE<<< The modification to the GPL is included to allow you to
+    distribute a combined work that includes FreeRTOS without being obliged to
+    provide the source code for proprietary components outside of the FreeRTOS
+    kernel.  FreeRTOS is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+    more details. You should have received a copy of the GNU General Public
+    License and the FreeRTOS license exception along with FreeRTOS; if not it
+    can be viewed here: http://www.freertos.org/a00114.html and also obtained
+    by writing to Richard Barry, contact details for whom are available on the
+    FreeRTOS WEB site.
+
+    1 tab == 4 spaces!
+
+    http://www.FreeRTOS.org - Documentation, latest information, license and
+    contact details.
+
+    http://www.SafeRTOS.com - A version that is certified for use in safety
+    critical systems.
+
+    http://www.OpenRTOS.com - Commercial support, development, porting,
+    licensing and training services.
+*/
+
+/*-----------------------------------------------------------
+ * Implementation of functions defined in portable.h for the ARM CM3 port.
+ *----------------------------------------------------------*/
+
+/* Scheduler includes. */
+#include "FreeRTOS.h"
+#include "task.h"
+
+/* For backward compatibility, ensure configKERNEL_INTERRUPT_PRIORITY is
+defined.  The value should also ensure backward compatibility.
+FreeRTOS.org versions prior to V4.4.0 did not include this definition. */
+#ifndef configKERNEL_INTERRUPT_PRIORITY
+	#define configKERNEL_INTERRUPT_PRIORITY 255
+#endif
+
+/* Constants required to manipulate the NVIC. */
+#define portNVIC_SYSTICK_CTRL		( ( volatile unsigned long *) 0xe000e010 )
+#define portNVIC_SYSTICK_LOAD		( ( volatile unsigned long *) 0xe000e014 )
+#define portNVIC_INT_CTRL			( ( volatile unsigned long *) 0xe000ed04 )
+#define portNVIC_SYSPRI2			( ( volatile unsigned long *) 0xe000ed20 )
+#define portNVIC_SYSTICK_CLK		0x00000004
+#define portNVIC_SYSTICK_INT		0x00000002
+#define portNVIC_SYSTICK_ENABLE		0x00000001
+#define portNVIC_PENDSVSET			0x10000000
+#define portNVIC_PENDSV_PRI			( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16 )
+#define portNVIC_SYSTICK_PRI		( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24 )
+
+/* Constants required to set up the initial stack. */
+#define portINITIAL_XPSR			( 0x01000000 )
+
+/* The priority used by the kernel is assigned to a variable to make access
+from inline assembler easier. */
+const unsigned long ulKernelPriority = configKERNEL_INTERRUPT_PRIORITY;
+
+/* Each task maintains its own interrupt status in the critical nesting
+variable. */
+static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
+
+/*
+ * Setup the timer to generate the tick interrupts.
+ */
+static void prvSetupTimerInterrupt( void );
+
+/*
+ * Exception handlers.
+ */
+void xPortPendSVHandler( void ) __attribute__ (( naked ));
+void xPortSysTickHandler( void );
+void vPortSVCHandler( void ) __attribute__ (( naked ));
+
+/*
+ * Start first task is a separate function so it can be tested in isolation.
+ */
+void vPortStartFirstTask( void ) __attribute__ (( naked ));
+
+/*-----------------------------------------------------------*/
+
+/*
+ * See header file for description.
+ */
+portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
+{
+	/* Simulate the stack frame as it would be created by a context switch
+	interrupt. */
+	pxTopOfStack--; /* Offset added to account for the way the MCU uses the stack on entry/exit of interrupts. */
+	*pxTopOfStack = portINITIAL_XPSR;	/* xPSR */
+	pxTopOfStack--;
+	*pxTopOfStack = ( portSTACK_TYPE ) pxCode;	/* PC */
+	pxTopOfStack--;
+	*pxTopOfStack = 0;	/* LR */
+	pxTopOfStack -= 5;	/* R12, R3, R2 and R1. */
+	*pxTopOfStack = ( portSTACK_TYPE ) pvParameters;	/* R0 */
+	pxTopOfStack -= 8;	/* R11, R10, R9, R8, R7, R6, R5 and R4. */
+
+	return pxTopOfStack;
+}
+/*-----------------------------------------------------------*/
+
+// !!! Maple
+// void vPortSVCHandler( void )
+void __exc_svc( void )
+// !!! Maple
+{
+	__asm volatile (
+					"	ldr	r3, pxCurrentTCBConst2		\n" /* Restore the context. */
+					"	ldr r1, [r3]					\n" /* Use pxCurrentTCBConst to get the pxCurrentTCB address. */
+					"	ldr r0, [r1]					\n" /* The first item in pxCurrentTCB is the task top of stack. */
+					"	ldmia r0!, {r4-r11}				\n" /* Pop the registers that are not automatically saved on exception entry and the critical nesting count. */
+					"	msr psp, r0						\n" /* Restore the task stack pointer. */
+					"	mov r0, #0 						\n"
+					"	msr	basepri, r0					\n"
+					"	orr r14, #0xd					\n"
+					"	bx r14							\n"
+					"									\n"
+					"	.align 2						\n"
+					"pxCurrentTCBConst2: .word pxCurrentTCB				\n"
+				);
+}
+/*-----------------------------------------------------------*/
+
+void vPortStartFirstTask( void )
+{
+	__asm volatile(
+					" ldr r0, =0xE000ED08 	\n" /* Use the NVIC offset register to locate the stack. */
+					" ldr r0, [r0] 			\n"
+					" ldr r0, [r0] 			\n"
+					" msr msp, r0			\n" /* Set the msp back to the start of the stack. */
+					" cpsie i				\n" /* Globally enable interrupts. */
+					" svc 0					\n" /* System call to start first task. */
+					" nop					\n"
+				);
+}
+/*-----------------------------------------------------------*/
+
+/*
+ * See header file for description.
+ */
+portBASE_TYPE xPortStartScheduler( void )
+{
+	/* Make PendSV, CallSV and SysTick the same priroity as the kernel. */
+	*(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI;
+	*(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI;
+
+// !!! Maple
+	systick_attach_callback(&xPortSysTickHandler);
+//	/* Start the timer that generates the tick ISR.  Interrupts are disabled
+//	here already. */
+//	prvSetupTimerInterrupt();
+// !!! Maple
+
+	/* Initialise the critical nesting count ready for the first task. */
+	uxCriticalNesting = 0;
+
+	/* Start the first task. */
+	vPortStartFirstTask();
+
+	/* Should not get here! */
+	return 0;
+}
+/*-----------------------------------------------------------*/
+
+void vPortEndScheduler( void )
+{
+	/* It is unlikely that the CM3 port will require this function as there
+	is nothing to return to.  */
+}
+/*-----------------------------------------------------------*/
+
+void vPortYieldFromISR( void )
+{
+	/* Set a PendSV to request a context switch. */
+	*(portNVIC_INT_CTRL) = portNVIC_PENDSVSET;
+}
+/*-----------------------------------------------------------*/
+
+void vPortEnterCritical( void )
+{
+	portDISABLE_INTERRUPTS();
+	uxCriticalNesting++;
+}
+/*-----------------------------------------------------------*/
+
+void vPortExitCritical( void )
+{
+	uxCriticalNesting--;
+	if( uxCriticalNesting == 0 )
+	{
+		portENABLE_INTERRUPTS();
+	}
+}
+/*-----------------------------------------------------------*/
+
+// !!! Maple
+// void xPortPendSVHandler( void )
+void __exc_pendsv( void )
+// !!! Maple
+{
+	/* This is a naked function. */
+
+	__asm volatile
+	(
+	"	mrs r0, psp							\n"
+	"										\n"
+	"	ldr	r3, pxCurrentTCBConst			\n" /* Get the location of the current TCB. */
+	"	ldr	r2, [r3]						\n"
+	"										\n"
+	"	stmdb r0!, {r4-r11}					\n" /* Save the remaining registers. */
+	"	str r0, [r2]						\n" /* Save the new top of stack into the first member of the TCB. */
+	"										\n"
+	"	stmdb sp!, {r3, r14}				\n"
+	"	mov r0, %0							\n"
+	"	msr basepri, r0						\n"
+	"	bl vTaskSwitchContext				\n"
+	"	mov r0, #0							\n"
+	"	msr basepri, r0						\n"
+	"	ldmia sp!, {r3, r14}				\n"
+	"										\n"	/* Restore the context, including the critical nesting count. */
+	"	ldr r1, [r3]						\n"
+	"	ldr r0, [r1]						\n" /* The first item in pxCurrentTCB is the task top of stack. */
+	"	ldmia r0!, {r4-r11}					\n" /* Pop the registers. */
+	"	msr psp, r0							\n"
+	"	bx r14								\n"
+	"										\n"
+	"	.align 2							\n"
+	"pxCurrentTCBConst: .word pxCurrentTCB	\n"
+	::"i"(configMAX_SYSCALL_INTERRUPT_PRIORITY)
+	);
+}
+/*-----------------------------------------------------------*/
+
+void xPortSysTickHandler( void )
+{
+unsigned long 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 );
+}
+/*-----------------------------------------------------------*/
+
+/*
+ * Setup the systick timer to generate the tick interrupts at the required
+ * frequency.
+ */
+void prvSetupTimerInterrupt( void )
+{
+	/* Configure SysTick to interrupt at the requested rate. */
+	*(portNVIC_SYSTICK_LOAD) = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;
+	*(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;
+}
+/*-----------------------------------------------------------*/
+