FreeRTOS/Source/portable/Tasking/ARM_CM4F/port_asm.asm

;/*
;    FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
;
;
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	.extern pxCurrentTCB
	.extern vTaskSwitchContext
	.extern ulMaxSyscallInterruptPriorityConst

	.global PendSV_Handler
	.global SVC_Handler
	.global vPortStartFirstTask
	.global vPortEnableVFP
	
;-----------------------------------------------------------

	.section .text
	.thumb
	.align 4
PendSV_Handler: .type func
	mrs r0, psp

	;Get the location of the current TCB.
	ldr.w	r3, =pxCurrentTCB
	ldr	r2, [r3]

	;Is the task using the FPU context?  If so, push high vfp registers.
	tst r14, #0x10
	it eq
	vstmdbeq r0!, {s16-s31}

	;Save the core registers.
	stmdb r0!, {r4-r11, r14}

	;Save the new top of stack into the first member of the TCB.
	str r0, [r2]

	stmdb sp!, {r3, r14}
	ldr.w r0, =ulMaxSyscallInterruptPriorityConst
	msr basepri, r0
	bl vTaskSwitchContext
	mov r0, #0
	msr basepri, r0
	ldmia sp!, {r3, r14}

	;The first item in pxCurrentTCB is the task top of stack.
	ldr r1, [r3]
	ldr r0, [r1]

	;Pop the core registers.
	ldmia r0!, {r4-r11, r14}

	;Is the task using the FPU context?  If so, pop the high vfp registers too.
	tst r14, #0x10
	it eq
	vldmiaeq r0!, {s16-s31}

	msr psp, r0
	bx r14

	.size	PendSV_Handler, $-PendSV_Handler
	.endsec

;-----------------------------------------------------------

	.section .text
	.thumb
	.align 4
SVC_Handler: .type func
	;Get the location of the current TCB.
	ldr.w	r3, =pxCurrentTCB
	ldr r1, [r3]
	ldr r0, [r1]
	;Pop the core registers.
	ldmia r0!, {r4-r11, r14}
	msr psp, r0
	mov r0, #0
	msr	basepri, r0
	bx r14
	.size	SVC_Handler, $-SVC_Handler
	.endsec

;-----------------------------------------------------------

	.section .text
	.thumb
	.align 4
vPortStartFirstTask .type func
	;Use the NVIC offset register to locate the stack.
	ldr.w r0, =0xE000ED08
	ldr r0, [r0]
	ldr r0, [r0]
	;Set the msp back to the start of the stack.
	msr msp, r0
	;Call SVC to start the first task.
	cpsie i
	svc 0
	.size	vPortStartFirstTask, $-vPortStartFirstTask
	.endsec

;-----------------------------------------------------------

	.section .text
	.thumb
	.align 4
vPortEnableVFP .type func
	;The FPU enable bits are in the CPACR.
	ldr.w r0, =0xE000ED88
	ldr	r1, [r0]

	;Enable CP10 and CP11 coprocessors, then save back.
	orr	r1, r1, #( 0xf << 20 )
	str r1, [r0]
	bx	r14
	.size	vPortEnableVFP, $-vPortEnableVFP
	.endsec


	.end