2 FreeRTOS.org V5.3.0 - Copyright (C) 2003-2009 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License (version 2) as published
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8 by the Free Software Foundation and modified by the FreeRTOS exception.
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9 **NOTE** The exception to the GPL is included to allow you to distribute a
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10 combined work that includes FreeRTOS.org without being obliged to provide
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11 the source code for any proprietary components. Alternative commercial
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12 license and support terms are also available upon request. See the
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13 licensing section of http://www.FreeRTOS.org for full details.
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15 FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT
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16 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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17 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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20 You should have received a copy of the GNU General Public License along
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21 with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
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22 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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25 ***************************************************************************
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27 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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29 * This is a concise, step by step, 'hands on' guide that describes both *
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30 * general multitasking concepts and FreeRTOS specifics. It presents and *
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31 * explains numerous examples that are written using the FreeRTOS API. *
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32 * Full source code for all the examples is provided in an accompanying *
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35 ***************************************************************************
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39 Please ensure to read the configuration and relevant port sections of the
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40 online documentation.
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42 http://www.FreeRTOS.org - Documentation, latest information, license and
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45 http://www.SafeRTOS.com - A version that is certified for use in safety
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48 http://www.OpenRTOS.com - Commercial support, development, porting,
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49 licensing and training services.
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52 typedef void tskTCB;
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53 extern volatile tskTCB * volatile pxCurrentTCB;
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54 extern void vTaskSwitchContext( void );
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57 * Saves the stack pointer for one task into its TCB, calls
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58 * vTaskSwitchContext() to update the TCB being used, then restores the stack
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59 * from the new TCB read to run the task.
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61 void portSWITCH_CONTEXT( void );
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64 * Load the stack pointer from the TCB of the task which is going to be first
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65 * to execute. Then force an IRET so the registers and IP are popped off the
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68 void portFIRST_CONTEXT( void );
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70 #define portSWITCH_CONTEXT() \
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71 asm { mov ax, seg pxCurrentTCB } \
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72 asm { mov ds, ax } \
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73 asm { les bx, pxCurrentTCB } /* Save the stack pointer into the TCB. */ \
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74 asm { mov es:0x2[ bx ], ss } \
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75 asm { mov es:[ bx ], sp } \
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76 asm { call far ptr vTaskSwitchContext } /* Perform the switch. */ \
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77 asm { mov ax, seg pxCurrentTCB } /* Restore the stack pointer from the TCB. */ \
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78 asm { mov ds, ax } \
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79 asm { les bx, dword ptr pxCurrentTCB } \
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80 asm { mov ss, es:[ bx + 2 ] } \
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81 asm { mov sp, es:[ bx ] }
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83 #define portFIRST_CONTEXT() \
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84 asm { mov ax, seg pxCurrentTCB } \
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85 asm { mov ds, ax } \
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86 asm { les bx, dword ptr pxCurrentTCB } \
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87 asm { mov ss, es:[ bx + 2 ] } \
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88 asm { mov sp, es:[ bx ] } \
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