2 ; * FreeRTOS Kernel V10.0.1
\r
3 ; * Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
\r
5 ; * Permission is hereby granted, free of charge, to any person obtaining a copy of
\r
6 ; * this software and associated documentation files (the "Software"), to deal in
\r
7 ; * the Software without restriction, including without limitation the rights to
\r
8 ; * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
\r
9 ; * the Software, and to permit persons to whom the Software is furnished to do so,
\r
10 ; * subject to the following conditions:
\r
12 ; * The above copyright notice and this permission notice shall be included in all
\r
13 ; * copies or substantial portions of the Software.
\r
15 ; * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
\r
16 ; * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
\r
17 ; * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
\r
18 ; * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
\r
19 ; * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
\r
20 ; * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
\r
22 ; * http://www.FreeRTOS.org
\r
23 ; * http://aws.amazon.com/freertos
\r
25 ; * 1 tab == 4 spaces!
\r
28 #include "FreeRTOSConfig.h"
\r
30 SECTION .text:CODE:ROOT(2)
\r
33 /* Variables and functions. */
\r
35 EXTERN vTaskSwitchContext
\r
36 EXTERN vApplicationIRQHandler
\r
37 EXTERN ulPortInterruptNesting
\r
38 EXTERN ulPortTaskHasFPUContext
\r
39 EXTERN ulPortYieldRequired
\r
40 EXTERN ulCriticalNesting
\r
42 PUBLIC FreeRTOS_IRQ_Handler
\r
43 PUBLIC FreeRTOS_SVC_Handler
\r
44 PUBLIC vPortRestoreTaskContext
\r
50 portSAVE_CONTEXT MACRO
\r
52 /* Save the LR and SPSR onto the system mode stack before switching to
\r
53 system mode to save the remaining system mode registers. */
\r
54 SRSDB sp!, #SYS_MODE
\r
58 /* Push the critical nesting count. */
\r
59 LDR R2, =ulCriticalNesting
\r
63 /* Does the task have a floating point context that needs saving? If
\r
64 ulPortTaskHasFPUContext is 0 then no. */
\r
65 LDR R2, =ulPortTaskHasFPUContext
\r
69 /* Save the floating point context, if any. */
\r
72 #if configFPU_D32 == 1
\r
74 #endif /* configFPU_D32 */
\r
77 /* Save ulPortTaskHasFPUContext itself. */
\r
80 /* Save the stack pointer in the TCB. */
\r
81 LDR R0, =pxCurrentTCB
\r
87 ; /**********************************************************************/
\r
89 portRESTORE_CONTEXT MACRO
\r
91 /* Set the SP to point to the stack of the task being restored. */
\r
92 LDR R0, =pxCurrentTCB
\r
96 /* Is there a floating point context to restore? If the restored
\r
97 ulPortTaskHasFPUContext is zero then no. */
\r
98 LDR R0, =ulPortTaskHasFPUContext
\r
103 /* Restore the floating point context, if any. */
\r
105 #if configFPU_D32 == 1
\r
107 #endif /* configFPU_D32 */
\r
111 /* Restore the critical section nesting depth. */
\r
112 LDR R0, =ulCriticalNesting
\r
116 /* Restore all system mode registers other than the SP (which is already
\r
120 /* Return to the task code, loading CPSR on the way. */
\r
128 /******************************************************************************
\r
129 * SVC handler is used to yield.
\r
130 *****************************************************************************/
\r
131 FreeRTOS_SVC_Handler:
\r
132 /* Save the context of the current task and select a new task to run. */
\r
134 LDR R0, =vTaskSwitchContext
\r
136 portRESTORE_CONTEXT
\r
139 /******************************************************************************
\r
140 * vPortRestoreTaskContext is used to start the scheduler.
\r
141 *****************************************************************************/
\r
142 vPortRestoreTaskContext:
\r
143 /* Switch to system mode. */
\r
145 portRESTORE_CONTEXT
\r
147 FreeRTOS_IRQ_Handler:
\r
148 /* Return to the interrupted instruction. */
\r
151 /* Push the return address and SPSR. */
\r
156 /* Change to supervisor mode to allow reentry. */
\r
159 /* Push used registers. */
\r
162 /* Increment nesting count. r3 holds the address of ulPortInterruptNesting
\r
163 for future use. r1 holds the original ulPortInterruptNesting value for
\r
165 LDR r3, =ulPortInterruptNesting
\r
170 /* Ensure bit 2 of the stack pointer is clear. r2 holds the bit 2 value for
\r
176 /* Call the interrupt handler. */
\r
178 LDR r1, =vApplicationIRQHandler
\r
187 /* Write to the EOI register. */
\r
188 LDR r2, =configEOI_ADDRESS
\r
191 /* Restore the old nesting count. */
\r
194 /* A context switch is never performed if the nesting count is not 0. */
\r
196 BNE exit_without_switch
\r
198 /* Did the interrupt request a context switch? r1 holds the address of
\r
199 ulPortYieldRequired and r0 the value of ulPortYieldRequired for future
\r
201 LDR r1, =ulPortYieldRequired
\r
204 BNE switch_before_exit
\r
206 exit_without_switch:
\r
207 /* No context switch. Restore used registers, LR_irq and SPSR before
\r
216 switch_before_exit:
\r
217 /* A context swtich is to be performed. Clear the context switch pending
\r
222 /* Restore used registers, LR-irq and SPSR before saving the context
\r
223 to the task stack. */
\r
231 /* Call the function that selects the new task to execute.
\r
232 vTaskSwitchContext() if vTaskSwitchContext() uses LDRD or STRD
\r
233 instructions, or 8 byte aligned stack allocated data. LR does not need
\r
234 saving as a new LR will be loaded by portRESTORE_CONTEXT anyway. */
\r
235 LDR R0, =vTaskSwitchContext
\r
238 /* Restore the context of, and branch to, the task selected to execute
\r
240 portRESTORE_CONTEXT
\r