FreeRTOS/Source/portable/IAR/ARM_CM0/portasm.s

/*
    FreeRTOS V7.2.0 - Copyright (C) 2012 Real Time Engineers Ltd.
	

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    This file is part of the FreeRTOS distribution.

    FreeRTOS is free software; you can redistribute it and/or modify it under
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    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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*/

#include <FreeRTOSConfig.h>

/* For backward compatibility, ensure configKERNEL_INTERRUPT_PRIORITY is
defined.  The value zero should also ensure backward compatibility.
FreeRTOS.org versions prior to V4.3.0 did not include this definition. */
#ifndef configKERNEL_INTERRUPT_PRIORITY
	#define configKERNEL_INTERRUPT_PRIORITY 0
#endif

	
	RSEG    CODE:CODE(2)
	thumb

	EXTERN vPortYieldFromISR
	EXTERN pxCurrentTCB
	EXTERN vTaskSwitchContext

	PUBLIC vSetMSP
	PUBLIC xPortPendSVHandler
	PUBLIC vPortSVCHandler
	PUBLIC vPortStartFirstTask


/*-----------------------------------------------------------*/

vSetMSP
	msr msp, r0
	bx lr
	
/*-----------------------------------------------------------*/

xPortPendSVHandler:
	mrs r0, psp							
											
	ldr	r3, =pxCurrentTCB	/* Get the location of the current TCB. */
	ldr	r2, [r3]						
											
	subs r0, r0, #32		/* Make space for the remaining low registers. */
	str r0, [r2]			/* Save the new top of stack. */
	stmia r0!, {r4-r7}		/* Store the low registers that are not saved automatically. */
	mov r4, r8				/* Store the high registers. */
	mov r5, r9							
	mov r6, r10							
	mov r7, r11							
	stmia r0!, {r4-r7}              	
											
	push {r3, r14}						
	cpsid i								
	bl vTaskSwitchContext				
	cpsie i								
	pop {r2, r3}			/* lr goes in r3. r2 now holds tcb pointer. */
											
	ldr r1, [r2]						
	ldr r0, [r1]			/* The first item in pxCurrentTCB is the task top of stack. */
	adds r0, r0, #16		/* Move to the high registers. */
	ldmia r0!, {r4-r7}		/* Pop the high registers. */
	mov r8, r4							
	mov r9, r5							
	mov r10, r6							
	mov r11, r7							
											
	msr psp, r0				/* Remember the new top of stack for the task. */
											
	subs r0, r0, #32		/* Go back for the low registers that are not automatically restored. */
	ldmia r0!, {r4-r7}		/* Pop low registers.  */
											
	bx r3								

/*-----------------------------------------------------------*/

vPortSVCHandler;
	ldr	r3, =pxCurrentTCB	/* Restore the context. */
	ldr r1, [r3]			/* Get the pxCurrentTCB address. */
	ldr r0, [r1]			/* The first item in pxCurrentTCB is the task top of stack. */
	adds r0, r0, #16		/* Move to the high registers. */
	ldmia r0!, {r4-r7}		/* Pop the high registers. */
	mov r8, r4						
	mov r9, r5						
	mov r10, r6						
	mov r11, r7						
										
	msr psp, r0				/* Remember the new top of stack for the task. */
										
	subs r0, r0, #32		/* Go back for the low registers that are not automatically restored. */
	ldmia r0!, {r4-r7}		/* Pop low registers.  */
	mov r1, r14				/* OR R14 with 0x0d. */
	movs r0, #0x0d					
	orrs r1, r0						
	bx r1							

/*-----------------------------------------------------------*/

vPortStartFirstTask
	movs r0, #0x00 	 		/* Locate the top of stack. */
	ldr r0, [r0] 		
	msr msp, r0		 		/* Set the msp back to the start of the stack. */
	cpsie i			 		/* Globally enable interrupts. */
	svc 0			 		/* System call to start first task. */
	nop				
	
	END