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

   1 /*\r
   2         FreeRTOS.org V4.3.0 - Copyright (C) 2003-2007 Richard Barry.\r
   3 \r
   4         This file is part of the FreeRTOS.org distribution.\r
   5 \r
   6         FreeRTOS.org is free software; you can redistribute it and/or modify\r
   7         it under the terms of the GNU General Public License as published by\r
   8         the Free Software Foundation; either version 2 of the License, or\r
   9         (at your option) any later version.\r
  10 \r
  11         FreeRTOS.org is distributed in the hope that it will be useful,\r
  12         but WITHOUT ANY WARRANTY; without even the implied warranty of\r
  13         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\r
  14         GNU General Public License for more details.\r
  15 \r
  16         You should have received a copy of the GNU General Public License\r
  17         along with FreeRTOS.org; if not, write to the Free Software\r
  18         Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA\r
  19 \r
  20         A special exception to the GPL can be applied should you wish to distribute\r
  21         a combined work that includes FreeRTOS.org, without being obliged to provide\r
  22         the source code for any proprietary components.  See the licensing section \r
  23         of http://www.FreeRTOS.org for full details of how and when the exception\r
  24         can be applied.\r
  25 \r
  26         ***************************************************************************\r
  27         See http://www.FreeRTOS.org for documentation, latest information, license \r
  28         and contact details.  Please ensure to read the configuration and relevant \r
  29         port sections of the online documentation.\r
  30 \r
  31         Also see http://www.SafeRTOS.com for an IEC 61508 compliant version along\r
  32         with commercial development and support options.\r
  33         ***************************************************************************\r
  34 */\r
  35 \r
  36 typedef void tskTCB;\r
  37 extern volatile tskTCB * volatile pxCurrentTCB;\r
  38 extern void vTaskSwitchContext( void );\r
  39 \r
  40 /* \r
  41  * Saves the stack pointer for one task into its TCB, calls \r
  42  * vTaskSwitchContext() to update the TCB being used, then restores the stack \r
  43  * from the new TCB read to run the task. \r
  44  */\r
  45 void portSWITCH_CONTEXT( void );\r
  46 \r
  47 /*\r
  48  * Load the stack pointer from the TCB of the task which is going to be first\r
  49  * to execute.  Then force an IRET so the registers and IP are popped off the\r
  50  * stack.\r
  51  */\r
  52 void portFIRST_CONTEXT( void );\r
  53 \r
  54 /* There are slightly different versions depending on whether you are building\r
  55 to include debugger information.  If debugger information is used then there\r
  56 are a couple of extra bytes left of the ISR stack (presumably for use by the\r
  57 debugger).  The true stack pointer is then stored in the bp register.  We add\r
  58 2 to the stack pointer to remove the extra bytes before we restore our context. */\r
  59 \r
  60 #ifdef DEBUG_BUILD\r
  61 \r
  62         #pragma aux portSWITCH_CONTEXT =        "mov    ax, seg pxCurrentTCB"                                                                                                           \\r
  63                                                                                 "mov    ds, ax"                                                                                                                                         \\r
  64                                                                                 "les    bx, pxCurrentTCB"                       /* Save the stack pointer into the TCB. */              \\r
  65                                                                                 "mov    es:0x2[ bx ], ss"                                                                                                                       \\r
  66                                                                                 "mov    es:[ bx ], sp"                                                                                                                          \\r
  67                                                                                 "call   vTaskSwitchContext"                     /* Perform the switch. */                                               \\r
  68                                                                                 "mov    ax, seg pxCurrentTCB"           /* Restore the stack pointer from the TCB. */   \\r
  69                                                                                 "mov    ds, ax"                                                                                                                                         \\r
  70                                                                                 "les    bx, dword ptr pxCurrentTCB"                                                                                                     \\r
  71                                                                                 "mov    ss, es:[ bx + 2 ]"                                                                                                                      \\r
  72                                                                                 "mov    sp, es:[ bx ]"                                                                                                                          \\r
  73                                                                                 "mov    bp, sp"                                         /* Prepair the bp register for the restoration of the SP in the compiler generated portion of the ISR */        \\r
  74                                                                                 "add    bp, 0x0002"\r
  75 \r
  76                                                                                 \r
  77 \r
  78         #pragma aux portFIRST_CONTEXT =         "mov    ax, seg pxCurrentTCB"                   \\r
  79                                                                                 "mov    ds, ax"                                                 \\r
  80                                                                                 "les    bx, dword ptr pxCurrentTCB"             \\r
  81                                                                                 "mov    ss, es:[ bx + 2 ]"                              \\r
  82                                                                                 "mov    sp, es:[ bx ]"                                  \\r
  83                                                                                 "add    sp, 0x0002"                                             /* Remove the extra bytes that exist in debug builds before restoring the context. */ \\r
  84                                                                                 "pop    ax"                                                             \\r
  85                                                                                 "pop    ax"                                                             \\r
  86                                                                                 "pop    es"                                                             \\r
  87                                                                                 "pop    ds"                                                             \\r
  88                                                                                 "popa"                                                                  \\r
  89                                                                                 "iret"                                                                  \r
  90 #else\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                                                                                 \r
 104 \r
 105         #pragma aux portFIRST_CONTEXT =         "mov    ax, seg pxCurrentTCB"                   \\r
 106                                                                                 "mov    ds, ax"                                                 \\r
 107                                                                                 "les    bx, dword ptr pxCurrentTCB"             \\r
 108                                                                                 "mov    ss, es:[ bx + 2 ]"                              \\r
 109                                                                                 "mov    sp, es:[ bx ]"                                  \\r
 110                                                                                 "pop    ax"                                                             \\r
 111                                                                                 "pop    ax"                                                             \\r
 112                                                                                 "pop    es"                                                             \\r
 113                                                                                 "pop    ds"                                                             \\r
 114                                                                                 "popa"                                                                  \\r
 115                                                                                 "iret"                                                                  \r
 116 #endif\r
 117 \r
 118 \r