2 FreeRTOS V6.0.1 - Copyright (C) 2009 Real Time Engineers Ltd.
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4 ***************************************************************************
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8 * + New to FreeRTOS, *
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9 * + Wanting to learn FreeRTOS or multitasking in general quickly *
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10 * + Looking for basic training, *
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11 * + Wanting to improve your FreeRTOS skills and productivity *
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13 * then take a look at the FreeRTOS eBook *
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15 * "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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16 * http://www.FreeRTOS.org/Documentation *
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18 * A pdf reference manual is also available. Both are usually delivered *
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19 * to your inbox within 20 minutes to two hours when purchased between 8am *
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20 * and 8pm GMT (although please allow up to 24 hours in case of *
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21 * exceptional circumstances). Thank you for your support! *
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23 ***************************************************************************
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25 This file is part of the FreeRTOS distribution.
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27 FreeRTOS is free software; you can redistribute it and/or modify it under
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28 the terms of the GNU General Public License (version 2) as published by the
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29 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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30 ***NOTE*** The exception to the GPL is included to allow you to distribute
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31 a combined work that includes FreeRTOS without being obliged to provide the
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32 source code for proprietary components outside of the FreeRTOS kernel.
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33 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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34 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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35 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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36 more details. You should have received a copy of the GNU General Public
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37 License and the FreeRTOS license exception along with FreeRTOS; if not it
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38 can be viewed here: http://www.freertos.org/a00114.html and also obtained
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39 by writing to Richard Barry, contact details for whom are available on the
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44 http://www.FreeRTOS.org - Documentation, latest information, license and
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47 http://www.SafeRTOS.com - A version that is certified for use in safety
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50 http://www.OpenRTOS.com - Commercial support, development, porting,
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51 licensing and training services.
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54 typedef void tskTCB;
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55 extern volatile tskTCB * volatile pxCurrentTCB;
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56 extern void vTaskSwitchContext( void );
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59 * Saves the stack pointer for one task into its TCB, calls
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60 * vTaskSwitchContext() to update the TCB being used, then restores the stack
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61 * from the new TCB read to run the task.
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63 void portSWITCH_CONTEXT( void );
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66 * Load the stack pointer from the TCB of the task which is going to be first
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67 * to execute. Then force an IRET so the registers and IP are popped off the
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70 void portFIRST_CONTEXT( void );
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72 /* There are slightly different versions depending on whether you are building
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73 to include debugger information. If debugger information is used then there
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74 are a couple of extra bytes left of the ISR stack (presumably for use by the
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75 debugger). The true stack pointer is then stored in the bp register. We add
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76 2 to the stack pointer to remove the extra bytes before we restore our context. */
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80 #pragma aux portSWITCH_CONTEXT = "mov ax, seg pxCurrentTCB" \
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82 "les bx, pxCurrentTCB" /* Save the stack pointer into the TCB. */ \
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83 "mov es:0x2[ bx ], ss" \
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84 "mov es:[ bx ], sp" \
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85 "call vTaskSwitchContext" /* Perform the switch. */ \
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86 "mov ax, seg pxCurrentTCB" /* Restore the stack pointer from the TCB. */ \
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88 "les bx, dword ptr pxCurrentTCB" \
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89 "mov ss, es:[ bx + 2 ]" \
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90 "mov sp, es:[ bx ]" \
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91 "mov bp, sp" /* Prepair the bp register for the restoration of the SP in the compiler generated portion of the ISR */ \
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96 #pragma aux portFIRST_CONTEXT = "mov ax, seg pxCurrentTCB" \
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98 "les bx, dword ptr pxCurrentTCB" \
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99 "mov ss, es:[ bx + 2 ]" \
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100 "mov sp, es:[ bx ]" \
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101 "add sp, 0x0002" /* Remove the extra bytes that exist in debug builds before restoring the context. */ \
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110 #pragma aux portSWITCH_CONTEXT = "mov ax, seg pxCurrentTCB" \
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112 "les bx, pxCurrentTCB" /* Save the stack pointer into the TCB. */ \
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113 "mov es:0x2[ bx ], ss" \
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114 "mov es:[ bx ], sp" \
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115 "call vTaskSwitchContext" /* Perform the switch. */ \
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116 "mov ax, seg pxCurrentTCB" /* Restore the stack pointer from the TCB. */ \
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118 "les bx, dword ptr pxCurrentTCB" \
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119 "mov ss, es:[ bx + 2 ]" \
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120 "mov sp, es:[ bx ]"
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123 #pragma aux portFIRST_CONTEXT = "mov ax, seg pxCurrentTCB" \
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125 "les bx, dword ptr pxCurrentTCB" \
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126 "mov ss, es:[ bx + 2 ]" \
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127 "mov sp, es:[ bx ]" \
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projects / freertos / blob