2 FreeRTOS V8.2.2 - Copyright (C) 2015 Real Time Engineers Ltd.
\r
6 ***************************************************************************
\r
8 * FreeRTOS tutorial books are available in pdf and paperback. *
\r
9 * Complete, revised, and edited pdf reference manuals are also *
\r
12 * Purchasing FreeRTOS documentation will not only help you, by *
\r
13 * ensuring you get running as quickly as possible and with an *
\r
14 * in-depth knowledge of how to use FreeRTOS, it will also help *
\r
15 * the FreeRTOS project to continue with its mission of providing *
\r
16 * professional grade, cross platform, de facto standard solutions *
\r
17 * for microcontrollers - completely free of charge! *
\r
19 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
\r
21 * Thank you for using FreeRTOS, and thank you for your support! *
\r
23 ***************************************************************************
\r
26 This file is part of the FreeRTOS distribution.
\r
28 FreeRTOS is free software; you can redistribute it and/or modify it under
\r
29 the terms of the GNU General Public License (version 2) as published by the
\r
30 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
\r
31 >>>NOTE<<< The modification to the GPL is included to allow you to
\r
32 distribute a combined work that includes FreeRTOS without being obliged to
\r
33 provide the source code for proprietary components outside of the FreeRTOS
\r
34 kernel. FreeRTOS is distributed in the hope that it will be useful, but
\r
35 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
\r
36 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
\r
37 more details. You should have received a copy of the GNU General Public
\r
38 License and the FreeRTOS license exception along with FreeRTOS; if not it
\r
39 can be viewed here: http://www.freertos.org/a00114.html and also obtained
\r
40 by writing to Richard Barry, contact details for whom are available on the
\r
45 http://www.FreeRTOS.org - Documentation, latest information, license and
\r
48 http://www.SafeRTOS.com - A version that is certified for use in safety
\r
51 http://www.OpenRTOS.com - Commercial support, development, porting,
\r
52 licensing and training services.
\r
62 /* Variables and functions. */
\r
63 .extern ulMaxAPIPriorityMask
\r
64 .extern _freertos_vector_table
\r
65 .extern pxCurrentTCB
\r
66 .extern vTaskSwitchContext
\r
67 .extern vApplicationIRQHandler
\r
68 .extern ulPortInterruptNesting
\r
69 .extern ulPortTaskHasFPUContext
\r
71 .extern ulPortYieldRequired
\r
73 .global FreeRTOS_IRQ_Handler
\r
74 .global FreeRTOS_SVC_Handler
\r
75 .global vPortRestoreTaskContext
\r
80 .macro portSAVE_CONTEXT
\r
82 /* Save the LR and SPSR onto the system mode stack before switching to
\r
83 system mode to save the remaining system mode registers. */
\r
84 SRSDB sp!, #SYS_MODE
\r
88 /* Push the critical nesting count. */
\r
89 LDR R2, ulCriticalNestingConst
\r
93 /* Does the task have a floating point context that needs saving? If
\r
94 ulPortTaskHasFPUContext is 0 then no. */
\r
95 LDR R2, ulPortTaskHasFPUContextConst
\r
99 /* Save the floating point context, if any. */
\r
102 #if configFPU_D32 == 1
\r
104 #endif /* configFPU_D32 */
\r
107 /* Save ulPortTaskHasFPUContext itself. */
\r
110 /* Save the stack pointer in the TCB. */
\r
111 LDR R0, pxCurrentTCBConst
\r
117 ; /**********************************************************************/
\r
119 .macro portRESTORE_CONTEXT
\r
121 /* Set the SP to point to the stack of the task being restored. */
\r
122 LDR R0, pxCurrentTCBConst
\r
126 /* Is there a floating point context to restore? If the restored
\r
127 ulPortTaskHasFPUContext is zero then no. */
\r
128 LDR R0, ulPortTaskHasFPUContextConst
\r
133 /* Restore the floating point context, if any. */
\r
135 #if configFPU_D32 == 1
\r
137 #endif /* configFPU_D32 */
\r
141 /* Restore the critical section nesting depth. */
\r
142 LDR R0, ulCriticalNestingConst
\r
146 /* Restore all system mode registers other than the SP (which is already
\r
150 /* Return to the task code, loading CPSR on the way. */
\r
158 /******************************************************************************
\r
159 * SVC handler is used to yield.
\r
160 *****************************************************************************/
\r
162 .type FreeRTOS_SVC_Handler, %function
\r
163 FreeRTOS_SVC_Handler:
\r
164 /* Save the context of the current task and select a new task to run. */
\r
166 LDR R0, vTaskSwitchContextConst
\r
168 portRESTORE_CONTEXT
\r
171 /******************************************************************************
\r
172 * vPortRestoreTaskContext is used to start the scheduler.
\r
173 *****************************************************************************/
\r
175 .type vPortRestoreTaskContext, %function
\r
176 vPortRestoreTaskContext:
\r
177 /* Switch to system mode. */
\r
179 portRESTORE_CONTEXT
\r
182 .type FreeRTOS_IRQ_Handler, %function
\r
183 FreeRTOS_IRQ_Handler:
\r
184 /* Return to the interrupted instruction. */
\r
187 /* Push the return address and SPSR. */
\r
192 /* Change to supervisor mode to allow reentry. */
\r
194 /* Push used registers. */
\r
197 /* Increment nesting count. r3 holds the address of ulPortInterruptNesting
\r
198 for future use. r1 holds the original ulPortInterruptNesting value for
\r
200 LDR r3, ulPortInterruptNestingConst
\r
205 /* Ensure bit 2 of the stack pointer is clear. r2 holds the bit 2 value for
\r
211 /* Call the interrupt handler. */
\r
213 LDR r1, vApplicationIRQHandlerConst
\r
222 /* Write to the EOI register. */
\r
223 LDR r4, ulICCEOIRConst
\r
227 /* Restore the old nesting count. */
\r
230 /* A context switch is never performed if the nesting count is not 0. */
\r
232 BNE exit_without_switch
\r
234 /* Did the interrupt request a context switch? r1 holds the address of
\r
235 ulPortYieldRequired and r0 the value of ulPortYieldRequired for future
\r
237 LDR r1, =ulPortYieldRequired
\r
240 BNE switch_before_exit
\r
242 exit_without_switch:
\r
243 /* No context switch. Restore used registers, LR_irq and SPSR before
\r
252 switch_before_exit:
\r
253 /* A context swtich is to be performed. Clear the context switch pending
\r
258 /* Restore used registers, LR-irq and SPSR before saving the context
\r
259 to the task stack. */
\r
267 /* Call the function that selects the new task to execute.
\r
268 vTaskSwitchContext() if vTaskSwitchContext() uses LDRD or STRD
\r
269 instructions, or 8 byte aligned stack allocated data. LR does not need
\r
270 saving as a new LR will be loaded by portRESTORE_CONTEXT anyway. */
\r
271 LDR R0, vTaskSwitchContextConst
\r
274 /* Restore the context of, and branch to, the task selected to execute
\r
276 portRESTORE_CONTEXT
\r
278 ulICCEOIRConst: .word ulICCEOIR
\r
279 pxCurrentTCBConst: .word pxCurrentTCB
\r
280 ulCriticalNestingConst: .word ulCriticalNesting
\r
281 ulPortTaskHasFPUContextConst: .word ulPortTaskHasFPUContext
\r
282 vTaskSwitchContextConst: .word vTaskSwitchContext
\r
283 vApplicationIRQHandlerConst: .word vApplicationIRQHandler
\r
284 ulPortInterruptNestingConst: .word ulPortInterruptNesting
\r