git.sur5r.net Git - freertos/blob - FreeRTOS/Source/portable/oWatcom/16BitDOS/common/portasm.h

   1 /*\r
   2     FreeRTOS V8.1.1 - Copyright (C) 2014 Real Time Engineers Ltd. \r
   3     All rights reserved\r
   4 \r
   5     VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.\r
   6 \r
   7     ***************************************************************************\r
   8      *                                                                       *\r
   9      *    FreeRTOS provides completely free yet professionally developed,    *\r
  10      *    robust, strictly quality controlled, supported, and cross          *\r
  11      *    platform software that has become a de facto standard.             *\r
  12      *                                                                       *\r
  13      *    Help yourself get started quickly and support the FreeRTOS         *\r
  14      *    project by purchasing a FreeRTOS tutorial book, reference          *\r
  15      *    manual, or both from: http://www.FreeRTOS.org/Documentation        *\r
  16      *                                                                       *\r
  17      *    Thank you!                                                         *\r
  18      *                                                                       *\r
  19     ***************************************************************************\r
  20 \r
  21     This file is part of the FreeRTOS distribution.\r
  22 \r
  23     FreeRTOS is free software; you can redistribute it and/or modify it under\r
  24     the terms of the GNU General Public License (version 2) as published by the\r
  25     Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.\r
  26 \r
  27     >>!   NOTE: The modification to the GPL is included to allow you to     !<<\r
  28     >>!   distribute a combined work that includes FreeRTOS without being   !<<\r
  29     >>!   obliged to provide the source code for proprietary components     !<<\r
  30     >>!   outside of the FreeRTOS kernel.                                   !<<\r
  31 \r
  32     FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY\r
  33     WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS\r
  34     FOR A PARTICULAR PURPOSE.  Full license text is available from the following\r
  35     link: http://www.freertos.org/a00114.html\r
  36 \r
  37     1 tab == 4 spaces!\r
  38 \r
  39     ***************************************************************************\r
  40      *                                                                       *\r
  41      *    Having a problem?  Start by reading the FAQ "My application does   *\r
  42      *    not run, what could be wrong?"                                     *\r
  43      *                                                                       *\r
  44      *    http://www.FreeRTOS.org/FAQHelp.html                               *\r
  45      *                                                                       *\r
  46     ***************************************************************************\r
  47 \r
  48     http://www.FreeRTOS.org - Documentation, books, training, latest versions,\r
  49     license and Real Time Engineers Ltd. contact details.\r
  50 \r
  51     http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,\r
  52     including FreeRTOS+Trace - an indispensable productivity tool, a DOS\r
  53     compatible FAT file system, and our tiny thread aware UDP/IP stack.\r
  54 \r
  55     http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High\r
  56     Integrity Systems to sell under the OpenRTOS brand.  Low cost OpenRTOS\r
  57     licenses offer ticketed support, indemnification and middleware.\r
  58 \r
  59     http://www.SafeRTOS.com - High Integrity Systems also provide a safety\r
  60     engineered and independently SIL3 certified version for use in safety and\r
  61     mission critical applications that require provable dependability.\r
  62 \r
  63     1 tab == 4 spaces!\r
  64 */\r
  65 \r
  66 typedef void TCB_t;\r
  67 extern volatile TCB_t * volatile pxCurrentTCB;\r
  68 extern void vTaskSwitchContext( void );\r
  69 \r
  70 /* \r
  71  * Saves the stack pointer for one task into its TCB, calls \r
  72  * vTaskSwitchContext() to update the TCB being used, then restores the stack \r
  73  * from the new TCB read to run the task. \r
  74  */\r
  75 void portSWITCH_CONTEXT( void );\r
  76 \r
  77 /*\r
  78  * Load the stack pointer from the TCB of the task which is going to be first\r
  79  * to execute.  Then force an IRET so the registers and IP are popped off the\r
  80  * stack.\r
  81  */\r
  82 void portFIRST_CONTEXT( void );\r
  83 \r
  84 /* There are slightly different versions depending on whether you are building\r
  85 to include debugger information.  If debugger information is used then there\r
  86 are a couple of extra bytes left of the ISR stack (presumably for use by the\r
  87 debugger).  The true stack pointer is then stored in the bp register.  We add\r
  88 2 to the stack pointer to remove the extra bytes before we restore our context. */\r
  89 \r
  90 #ifdef DEBUG_BUILD\r
  91 \r
  92         #pragma aux portSWITCH_CONTEXT =        "mov    ax, seg pxCurrentTCB"                                                                                                           \\r
  93                                                                                 "mov    ds, ax"                                                                                                                                         \\r
  94                                                                                 "les    bx, pxCurrentTCB"                       /* Save the stack pointer into the TCB. */              \\r
  95                                                                                 "mov    es:0x2[ bx ], ss"                                                                                                                       \\r
  96                                                                                 "mov    es:[ bx ], sp"                                                                                                                          \\r
  97                                                                                 "call   vTaskSwitchContext"                     /* Perform the switch. */                                               \\r
  98                                                                                 "mov    ax, seg pxCurrentTCB"           /* Restore the stack pointer from the TCB. */   \\r
  99                                                                                 "mov    ds, ax"                                                                                                                                         \\r
 100                                                                                 "les    bx, dword ptr pxCurrentTCB"                                                                                                     \\r
 101                                                                                 "mov    ss, es:[ bx + 2 ]"                                                                                                                      \\r
 102                                                                                 "mov    sp, es:[ bx ]"                                                                                                                          \\r
 103                                                                                 "mov    bp, sp"                                         /* Prepair the bp register for the restoration of the SP in the compiler generated portion of the ISR */        \\r
 104                                                                                 "add    bp, 0x0002"\r
 105 \r
 106                                                                                 \r
 107 \r
 108         #pragma aux portFIRST_CONTEXT =         "mov    ax, seg pxCurrentTCB"                   \\r
 109                                                                                 "mov    ds, ax"                                                 \\r
 110                                                                                 "les    bx, dword ptr pxCurrentTCB"             \\r
 111                                                                                 "mov    ss, es:[ bx + 2 ]"                              \\r
 112                                                                                 "mov    sp, es:[ bx ]"                                  \\r
 113                                                                                 "add    sp, 0x0002"                                             /* Remove the extra bytes that exist in debug builds before restoring the context. */ \\r
 114                                                                                 "pop    ax"                                                             \\r
 115                                                                                 "pop    ax"                                                             \\r
 116                                                                                 "pop    es"                                                             \\r
 117                                                                                 "pop    ds"                                                             \\r
 118                                                                                 "popa"                                                                  \\r
 119                                                                                 "iret"                                                                  \r
 120 #else\r
 121 \r
 122         #pragma aux portSWITCH_CONTEXT =        "mov    ax, seg pxCurrentTCB"                                                                                                           \\r
 123                                                                                 "mov    ds, ax"                                                                                                                                         \\r
 124                                                                                 "les    bx, pxCurrentTCB"                       /* Save the stack pointer into the TCB. */              \\r
 125                                                                                 "mov    es:0x2[ bx ], ss"                                                                                                                       \\r
 126                                                                                 "mov    es:[ bx ], sp"                                                                                                                          \\r
 127                                                                                 "call   vTaskSwitchContext"                     /* Perform the switch. */                                               \\r
 128                                                                                 "mov    ax, seg pxCurrentTCB"           /* Restore the stack pointer from the TCB. */   \\r
 129                                                                                 "mov    ds, ax"                                                                                                                                         \\r
 130                                                                                 "les    bx, dword ptr pxCurrentTCB"                                                                                                     \\r
 131                                                                                 "mov    ss, es:[ bx + 2 ]"                                                                                                                      \\r
 132                                                                                 "mov    sp, es:[ bx ]"\r
 133                                                                                 \r
 134 \r
 135         #pragma aux portFIRST_CONTEXT =         "mov    ax, seg pxCurrentTCB"                   \\r
 136                                                                                 "mov    ds, ax"                                                 \\r
 137                                                                                 "les    bx, dword ptr pxCurrentTCB"             \\r
 138                                                                                 "mov    ss, es:[ bx + 2 ]"                              \\r
 139                                                                                 "mov    sp, es:[ bx ]"                                  \\r
 140                                                                                 "pop    ax"                                                             \\r
 141                                                                                 "pop    ax"                                                             \\r
 142                                                                                 "pop    es"                                                             \\r
 143                                                                                 "pop    ds"                                                             \\r
 144                                                                                 "popa"                                                                  \\r
 145                                                                                 "iret"                                                                  \r
 146 #endif\r
 147 \r
 148 \r