1/* 2 * FreeRTOS Kernel V11.1.0 3 * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved. 4 * 5 * SPDX-License-Identifier: MIT 6 * 7 * Permission is hereby granted, free of charge, to any person obtaining a copy of 8 * this software and associated documentation files (the "Software"), to deal in 9 * the Software without restriction, including without limitation the rights to 10 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of 11 * the Software, and to permit persons to whom the Software is furnished to do so, 12 * subject to the following conditions: 13 * 14 * The above copyright notice and this permission notice shall be included in all 15 * copies or substantial portions of the Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS 19 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR 20 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER 21 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 23 * 24 * https://www.FreeRTOS.org 25 * https://github.com/FreeRTOS 26 * 27 */ 28 29#include "PriorityDefinitions.h" 30 31 PUBLIC _prvStartFirstTask 32 PUBLIC ___interrupt_27 33 34 EXTERN _pxCurrentTCB 35 EXTERN _vTaskSwitchContext 36 37 RSEG CODE:CODE(4) 38 39_prvStartFirstTask: 40 41 /* When starting the scheduler there is nothing that needs moving to the 42 interrupt stack because the function is not called from an interrupt. 43 Just ensure the current stack is the user stack. */ 44 SETPSW U 45 46 /* Obtain the location of the stack associated with which ever task 47 pxCurrentTCB is currently pointing to. */ 48 MOV.L #_pxCurrentTCB, R15 49 MOV.L [R15], R15 50 MOV.L [R15], R0 51 52 /* Restore the registers from the stack of the task pointed to by 53 pxCurrentTCB. */ 54 POP R15 55 56 /* Accumulator low 32 bits. */ 57 MVTACLO R15, A0 58 POP R15 59 60 /* Accumulator high 32 bits. */ 61 MVTACHI R15, A0 62 POP R15 63 64 /* Accumulator guard. */ 65 MVTACGU R15, A0 66 POP R15 67 68 /* Accumulator low 32 bits. */ 69 MVTACLO R15, A1 70 POP R15 71 72 /* Accumulator high 32 bits. */ 73 MVTACHI R15, A1 74 POP R15 75 76 /* Accumulator guard. */ 77 MVTACGU R15, A1 78 POP R15 79 80 /* Floating point status word. */ 81 MVTC R15, FPSW 82 83 /* R1 to R15 - R0 is not included as it is the SP. */ 84 POPM R1-R15 85 86 /* This pops the remaining registers. */ 87 RTE 88 NOP 89 NOP 90 91/*-----------------------------------------------------------*/ 92 93/* The software interrupt - overwrite the default 'weak' definition. */ 94___interrupt_27: 95 96 /* Re-enable interrupts. */ 97 SETPSW I 98 99 /* Move the data that was automatically pushed onto the interrupt stack when 100 the interrupt occurred from the interrupt stack to the user stack. 101 102 R15 is saved before it is clobbered. */ 103 PUSH.L R15 104 105 /* Read the user stack pointer. */ 106 MVFC USP, R15 107 108 /* Move the address down to the data being moved. */ 109 SUB #12, R15 110 MVTC R15, USP 111 112 /* Copy the data across, R15, then PC, then PSW. */ 113 MOV.L [ R0 ], [ R15 ] 114 MOV.L 4[ R0 ], 4[ R15 ] 115 MOV.L 8[ R0 ], 8[ R15 ] 116 117 /* Move the interrupt stack pointer to its new correct position. */ 118 ADD #12, R0 119 120 /* All the rest of the registers are saved directly to the user stack. */ 121 SETPSW U 122 123 /* Save the rest of the general registers (R15 has been saved already). */ 124 PUSHM R1-R14 125 126 /* Save the FPSW and accumulator. */ 127 MVFC FPSW, R15 128 PUSH.L R15 129 MVFACGU #0, A1, R15 130 PUSH.L R15 131 MVFACHI #0, A1, R15 132 PUSH.L R15 133 /* Low order word. */ 134 MVFACLO #0, A1, R15 135 PUSH.L R15 136 MVFACGU #0, A0, R15 137 PUSH.L R15 138 MVFACHI #0, A0, R15 139 PUSH.L R15 140 /* Low order word. */ 141 MVFACLO #0, A0, R15 142 PUSH.L R15 143 144 /* Save the stack pointer to the TCB. */ 145 MOV.L #_pxCurrentTCB, R15 146 MOV.L [ R15 ], R15 147 MOV.L R0, [ R15 ] 148 149 /* Ensure the interrupt mask is set to the syscall priority while the kernel 150 structures are being accessed. */ 151 MVTIPL #configMAX_SYSCALL_INTERRUPT_PRIORITY 152 153 /* Select the next task to run. */ 154 BSR.A _vTaskSwitchContext 155 156 /* Reset the interrupt mask as no more data structure access is required. */ 157 MVTIPL #configKERNEL_INTERRUPT_PRIORITY 158 159 /* Load the stack pointer of the task that is now selected as the Running 160 state task from its TCB. */ 161 MOV.L #_pxCurrentTCB,R15 162 MOV.L [ R15 ], R15 163 MOV.L [ R15 ], R0 164 165 /* Restore the context of the new task. The PSW (Program Status Word) and 166 PC will be popped by the RTE instruction. */ 167 POP R15 168 169 /* Accumulator low 32 bits. */ 170 MVTACLO R15, A0 171 POP R15 172 173 /* Accumulator high 32 bits. */ 174 MVTACHI R15, A0 175 POP R15 176 177 /* Accumulator guard. */ 178 MVTACGU R15, A0 179 POP R15 180 181 /* Accumulator low 32 bits. */ 182 MVTACLO R15, A1 183 POP R15 184 185 /* Accumulator high 32 bits. */ 186 MVTACHI R15, A1 187 POP R15 188 189 /* Accumulator guard. */ 190 MVTACGU R15, A1 191 POP R15 192 MVTC R15, FPSW 193 POPM R1-R15 194 RTE 195 NOP 196 NOP 197 198/*-----------------------------------------------------------*/ 199 200 END 201
