portable/GCC/ARM_CRx_No_GIC/portASM.S - third_party/github/FreeRTOS/FreeRTOS-Kernel - Git at Google

 /*
  * FreeRTOS Kernel <DEVELOPMENT BRANCH>
  * Copyright (C) 2021 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
  *
  * SPDX-License-Identifier: MIT
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy of
  * this software and associated documentation files (the "Software"), to deal in
  * the Software without restriction, including without limitation the rights to
  * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
  * the Software, and to permit persons to whom the Software is furnished to do so,
  * subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in all
  * copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
  * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
  * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
  * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  *
  * https://www.FreeRTOS.org
  * https://github.com/FreeRTOS
  *
  */

 	.text
 	.arm

 	.set SYS_MODE,	0x1f
 	.set SVC_MODE,	0x13
 	.set IRQ_MODE,	0x12

 	/* Variables and functions. */
 	.extern ulMaxAPIPriorityMask
 	.extern _freertos_vector_table
 	.extern pxCurrentTCB
 	.extern vTaskSwitchContext
 	.extern vApplicationIRQHandler
 	.extern ulPortInterruptNesting
 	.extern ulPortTaskHasFPUContext
 	.extern ulICCEOIR
 	.extern ulPortYieldRequired

 	.global FreeRTOS_IRQ_Handler
 	.global FreeRTOS_SVC_Handler
 	.global vPortRestoreTaskContext


 .macro portSAVE_CONTEXT

 	/* Save the LR and SPSR onto the system mode stack before switching to
 	system mode to save the remaining system mode registers. */
 	SRSDB	sp!, #SYS_MODE
 	CPS		#SYS_MODE
 	PUSH	{R0-R12, R14}

 	/* Push the critical nesting count. */
 	LDR		R2, ulCriticalNestingConst
 	LDR		R1, [R2]
 	PUSH	{R1}

 	/* Does the task have a floating point context that needs saving?  If
 	ulPortTaskHasFPUContext is 0 then no. */
 	LDR		R2, ulPortTaskHasFPUContextConst
 	LDR		R3, [R2]
 	CMP		R3, #0

 	/* Save the floating point context, if any. */
 	FMRXNE  R1,  FPSCR
 	VPUSHNE {D0-D15}
 #if configFPU_D32 == 1
 	VPUSHNE	{D16-D31}
 #endif /* configFPU_D32 */
 	PUSHNE	{R1}

 	/* Save ulPortTaskHasFPUContext itself. */
 	PUSH	{R3}

 	/* Save the stack pointer in the TCB. */
 	LDR		R0, pxCurrentTCBConst
 	LDR		R1, [R0]
 	STR		SP, [R1]

 	.endm

 ; /**********************************************************************/

 .macro portRESTORE_CONTEXT

 	/* Set the SP to point to the stack of the task being restored. */
 	LDR		R0, pxCurrentTCBConst
 	LDR		R1, [R0]
 	LDR		SP, [R1]

 	/* Is there a floating point context to restore?  If the restored
 	ulPortTaskHasFPUContext is zero then no. */
 	LDR		R0, ulPortTaskHasFPUContextConst
 	POP		{R1}
 	STR		R1, [R0]
 	CMP		R1, #0

 	/* Restore the floating point context, if any. */
 	POPNE 	{R0}
 #if configFPU_D32 == 1
 	VPOPNE	{D16-D31}
 #endif /* configFPU_D32 */
 	VPOPNE	{D0-D15}
 	VMSRNE  FPSCR, R0

 	/* Restore the critical section nesting depth. */
 	LDR		R0, ulCriticalNestingConst
 	POP		{R1}
 	STR		R1, [R0]

 	/* Restore all system mode registers other than the SP (which is already
 	being used). */
 	POP		{R0-R12, R14}

 	/* Return to the task code, loading CPSR on the way. */
 	RFEIA	sp!

 	.endm


 /******************************************************************************
  * SVC handler is used to yield.
  *****************************************************************************/
 .align 4
 .type FreeRTOS_SVC_Handler, %function
 FreeRTOS_SVC_Handler:
 	/* Save the context of the current task and select a new task to run. */
 	portSAVE_CONTEXT
 	LDR R0, vTaskSwitchContextConst
 	BLX	R0
 	portRESTORE_CONTEXT


 /******************************************************************************
  * vPortRestoreTaskContext is used to start the scheduler.
  *****************************************************************************/
 .align 4
 .type vPortRestoreTaskContext, %function
 vPortRestoreTaskContext:
 	/* Switch to system mode. */
 	CPS		#SYS_MODE
 	portRESTORE_CONTEXT

 .align 4
 .type FreeRTOS_IRQ_Handler, %function
 FreeRTOS_IRQ_Handler:
 	/* Return to the interrupted instruction. */
 	SUB		lr, lr, #4

 	/* Push the return address and SPSR. */
 	PUSH	{lr}
 	MRS		lr, SPSR
 	PUSH	{lr}

 	/* Change to supervisor mode to allow reentry. */
 	CPS		#0x13

 	/* Push used registers. */
 	PUSH	{r0-r3, r12}

 	/* Increment nesting count.  r3 holds the address of ulPortInterruptNesting
 	for future use.  r1 holds the original ulPortInterruptNesting value for
 	future use. */
 	LDR		r3, ulPortInterruptNestingConst
 	LDR		r1, [r3]
 	ADD		r0, r1, #1
 	STR		r0, [r3]

 	/* Ensure bit 2 of the stack pointer is clear.  r2 holds the bit 2 value for
 	future use. */
 	MOV		r0, sp
 	AND		r2, r0, #4
 	SUB		sp, sp, r2

 	/* Call the interrupt handler. */
 	PUSH	{r0-r3, lr}
 	LDR		r1, vApplicationIRQHandlerConst
 	BLX		r1
 	POP		{r0-r3, lr}
 	ADD		sp, sp, r2

 	CPSID	i
 	DSB
 	ISB

 	/* Write to the EOI register. */
 	LDR 	r0, ulICCEOIRConst
 	LDR		r2, [r0]
 	STR		r0, [r2]

 	/* Restore the old nesting count. */
 	STR		r1, [r3]

 	/* A context switch is never performed if the nesting count is not 0. */
 	CMP		r1, #0
 	BNE		exit_without_switch

 	/* Did the interrupt request a context switch?  r1 holds the address of
 	ulPortYieldRequired and r0 the value of ulPortYieldRequired for future
 	use. */
 	LDR		r1, ulPortYieldRequiredConst
 	LDR		r0, [r1]
 	CMP		r0, #0
 	BNE		switch_before_exit

 exit_without_switch:
 	/* No context switch.  Restore used registers, LR_irq and SPSR before
 	returning. */
 	POP		{r0-r3, r12}
 	CPS		#IRQ_MODE
 	POP		{LR}
 	MSR		SPSR_cxsf, LR
 	POP		{LR}
 	MOVS	PC, LR

 switch_before_exit:
 	/* A context swtich is to be performed.  Clear the context switch pending
 	flag. */
 	MOV		r0, #0
 	STR		r0, [r1]

 	/* Restore used registers, LR-irq and SPSR before saving the context
 	to the task stack. */
 	POP		{r0-r3, r12}
 	CPS		#IRQ_MODE
 	POP		{LR}
 	MSR		SPSR_cxsf, LR
 	POP		{LR}
 	portSAVE_CONTEXT

 	/* Call the function that selects the new task to execute.
 	vTaskSwitchContext() if vTaskSwitchContext() uses LDRD or STRD
 	instructions, or 8 byte aligned stack allocated data.  LR does not need
 	saving as a new LR will be loaded by portRESTORE_CONTEXT anyway. */
 	LDR		R0, vTaskSwitchContextConst
 	BLX		R0

 	/* Restore the context of, and branch to, the task selected to execute
 	next. */
 	portRESTORE_CONTEXT

 ulICCEOIRConst:	.word ulICCEOIR
 pxCurrentTCBConst: .word pxCurrentTCB
 ulCriticalNestingConst: .word ulCriticalNesting
 ulPortTaskHasFPUContextConst: .word ulPortTaskHasFPUContext
 vTaskSwitchContextConst: .word vTaskSwitchContext
 vApplicationIRQHandlerConst: .word vApplicationIRQHandler
 ulPortInterruptNestingConst: .word ulPortInterruptNesting
 ulPortYieldRequiredConst: .word ulPortYieldRequired

 .end
	/*
	* FreeRTOS Kernel <DEVELOPMENT BRANCH>
	* Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
	*
	* SPDX-License-Identifier: MIT
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy of
	* this software and associated documentation files (the "Software"), to deal in
	* the Software without restriction, including without limitation the rights to
	* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
	* the Software, and to permit persons to whom the Software is furnished to do so,
	* subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in all
	* copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
	* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
	* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
	* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
	* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*
	* https://www.FreeRTOS.org
	* https://github.com/FreeRTOS
	*
	*/

	.text
	.arm

	.set SYS_MODE, 0x1f
	.set SVC_MODE, 0x13
	.set IRQ_MODE, 0x12

	/* Variables and functions. */
	.extern ulMaxAPIPriorityMask
	.extern _freertos_vector_table
	.extern pxCurrentTCB
	.extern vTaskSwitchContext
	.extern vApplicationIRQHandler
	.extern ulPortInterruptNesting
	.extern ulPortTaskHasFPUContext
	.extern ulICCEOIR
	.extern ulPortYieldRequired

	.global FreeRTOS_IRQ_Handler
	.global FreeRTOS_SVC_Handler
	.global vPortRestoreTaskContext


	.macro portSAVE_CONTEXT

	/* Save the LR and SPSR onto the system mode stack before switching to
	system mode to save the remaining system mode registers. */
	SRSDB sp!, #SYS_MODE
	CPS #SYS_MODE
	PUSH {R0-R12, R14}

	/* Push the critical nesting count. */
	LDR R2, ulCriticalNestingConst
	LDR R1, [R2]
	PUSH {R1}

	/* Does the task have a floating point context that needs saving? If
	ulPortTaskHasFPUContext is 0 then no. */
	LDR R2, ulPortTaskHasFPUContextConst
	LDR R3, [R2]
	CMP R3, #0

	/* Save the floating point context, if any. */
	FMRXNE R1, FPSCR
	VPUSHNE {D0-D15}
	#if configFPU_D32 == 1
	VPUSHNE {D16-D31}
	#endif /* configFPU_D32 */
	PUSHNE {R1}

	/* Save ulPortTaskHasFPUContext itself. */
	PUSH {R3}

	/* Save the stack pointer in the TCB. */
	LDR R0, pxCurrentTCBConst
	LDR R1, [R0]
	STR SP, [R1]

	.endm

	; /**********************************************************************/

	.macro portRESTORE_CONTEXT

	/* Set the SP to point to the stack of the task being restored. */
	LDR R0, pxCurrentTCBConst
	LDR R1, [R0]
	LDR SP, [R1]

	/* Is there a floating point context to restore? If the restored
	ulPortTaskHasFPUContext is zero then no. */
	LDR R0, ulPortTaskHasFPUContextConst
	POP {R1}
	STR R1, [R0]
	CMP R1, #0

	/* Restore the floating point context, if any. */
	POPNE {R0}
	#if configFPU_D32 == 1
	VPOPNE {D16-D31}
	#endif /* configFPU_D32 */
	VPOPNE {D0-D15}
	VMSRNE FPSCR, R0

	/* Restore the critical section nesting depth. */
	LDR R0, ulCriticalNestingConst
	POP {R1}
	STR R1, [R0]

	/* Restore all system mode registers other than the SP (which is already
	being used). */
	POP {R0-R12, R14}

	/* Return to the task code, loading CPSR on the way. */
	RFEIA sp!

	.endm




	/******************************************************************************
	* SVC handler is used to yield.
	*****************************************************************************/
	.align 4
	.type FreeRTOS_SVC_Handler, %function
	FreeRTOS_SVC_Handler:
	/* Save the context of the current task and select a new task to run. */
	portSAVE_CONTEXT
	LDR R0, vTaskSwitchContextConst
	BLX R0
	portRESTORE_CONTEXT


	/******************************************************************************
	* vPortRestoreTaskContext is used to start the scheduler.
	*****************************************************************************/
	.align 4
	.type vPortRestoreTaskContext, %function
	vPortRestoreTaskContext:
	/* Switch to system mode. */
	CPS #SYS_MODE
	portRESTORE_CONTEXT

	.align 4
	.type FreeRTOS_IRQ_Handler, %function
	FreeRTOS_IRQ_Handler:
	/* Return to the interrupted instruction. */
	SUB lr, lr, #4

	/* Push the return address and SPSR. */
	PUSH {lr}
	MRS lr, SPSR
	PUSH {lr}

	/* Change to supervisor mode to allow reentry. */
	CPS #0x13

	/* Push used registers. */
	PUSH {r0-r3, r12}

	/* Increment nesting count. r3 holds the address of ulPortInterruptNesting
	for future use. r1 holds the original ulPortInterruptNesting value for
	future use. */
	LDR r3, ulPortInterruptNestingConst
	LDR r1, [r3]
	ADD r0, r1, #1
	STR r0, [r3]

	/* Ensure bit 2 of the stack pointer is clear. r2 holds the bit 2 value for
	future use. */
	MOV r0, sp
	AND r2, r0, #4
	SUB sp, sp, r2

	/* Call the interrupt handler. */
	PUSH {r0-r3, lr}
	LDR r1, vApplicationIRQHandlerConst
	BLX r1
	POP {r0-r3, lr}
	ADD sp, sp, r2

	CPSID i
	DSB
	ISB

	/* Write to the EOI register. */
	LDR r0, ulICCEOIRConst
	LDR r2, [r0]
	STR r0, [r2]

	/* Restore the old nesting count. */
	STR r1, [r3]

	/* A context switch is never performed if the nesting count is not 0. */
	CMP r1, #0
	BNE exit_without_switch

	/* Did the interrupt request a context switch? r1 holds the address of
	ulPortYieldRequired and r0 the value of ulPortYieldRequired for future
	use. */
	LDR r1, ulPortYieldRequiredConst
	LDR r0, [r1]
	CMP r0, #0
	BNE switch_before_exit

	exit_without_switch:
	/* No context switch. Restore used registers, LR_irq and SPSR before
	returning. */
	POP {r0-r3, r12}
	CPS #IRQ_MODE
	POP {LR}
	MSR SPSR_cxsf, LR
	POP {LR}
	MOVS PC, LR

	switch_before_exit:
	/* A context swtich is to be performed. Clear the context switch pending
	flag. */
	MOV r0, #0
	STR r0, [r1]

	/* Restore used registers, LR-irq and SPSR before saving the context
	to the task stack. */
	POP {r0-r3, r12}
	CPS #IRQ_MODE
	POP {LR}
	MSR SPSR_cxsf, LR
	POP {LR}
	portSAVE_CONTEXT

	/* Call the function that selects the new task to execute.
	vTaskSwitchContext() if vTaskSwitchContext() uses LDRD or STRD
	instructions, or 8 byte aligned stack allocated data. LR does not need
	saving as a new LR will be loaded by portRESTORE_CONTEXT anyway. */
	LDR R0, vTaskSwitchContextConst
	BLX R0

	/* Restore the context of, and branch to, the task selected to execute
	next. */
	portRESTORE_CONTEXT

	ulICCEOIRConst: .word ulICCEOIR
	pxCurrentTCBConst: .word pxCurrentTCB
	ulCriticalNestingConst: .word ulCriticalNesting
	ulPortTaskHasFPUContextConst: .word ulPortTaskHasFPUContext
	vTaskSwitchContextConst: .word vTaskSwitchContext
	vApplicationIRQHandlerConst: .word vApplicationIRQHandler
	ulPortInterruptNestingConst: .word ulPortInterruptNesting
	ulPortYieldRequiredConst: .word ulPortYieldRequired

	.end