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

   1 /*\r
   2  * FreeRTOS Kernel V10.0.0\r
   3  * Copyright (C) 2017 Amazon.com, Inc. or its affiliates.  All Rights Reserved.\r
   4  *\r
   5  * Permission is hereby granted, free of charge, to any person obtaining a copy of\r
   6  * this software and associated documentation files (the "Software"), to deal in\r
   7  * the Software without restriction, including without limitation the rights to\r
   8  * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of\r
   9  * the Software, and to permit persons to whom the Software is furnished to do so,\r
  10  * subject to the following conditions:\r
  11  *\r
  12  * The above copyright notice and this permission notice shall be included in all\r
  13  * copies or substantial portions of the Software. If you wish to use our Amazon\r
  14  * FreeRTOS name, please do so in a fair use way that does not cause confusion.\r
  15  *\r
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR\r
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS\r
  18  * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR\r
  19  * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER\r
  20  * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN\r
  21  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.\r
  22  *\r
  23  * http://www.FreeRTOS.org\r
  24  * http://aws.amazon.com/freertos\r
  25  *\r
  26  * 1 tab == 4 spaces!\r
  27  */\r
  28 \r
  29 typedef void TCB_t;\r
  30 extern volatile TCB_t * volatile pxCurrentTCB;\r
  31 extern void vTaskSwitchContext( void );\r
  32 \r
  33 /* \r
  34  * Saves the stack pointer for one task into its TCB, calls \r
  35  * vTaskSwitchContext() to update the TCB being used, then restores the stack \r
  36  * from the new TCB read to run the task. \r
  37  */\r
  38 void portSWITCH_CONTEXT( void );\r
  39 \r
  40 /*\r
  41  * Load the stack pointer from the TCB of the task which is going to be first\r
  42  * to execute.  Then force an IRET so the registers and IP are popped off the\r
  43  * stack.\r
  44  */\r
  45 void portFIRST_CONTEXT( void );\r
  46 \r
  47 /* There are slightly different versions depending on whether you are building\r
  48 to include debugger information.  If debugger information is used then there\r
  49 are a couple of extra bytes left of the ISR stack (presumably for use by the\r
  50 debugger).  The true stack pointer is then stored in the bp register.  We add\r
  51 2 to the stack pointer to remove the extra bytes before we restore our context. */\r
  52 \r
  53 #ifdef DEBUG_BUILD\r
  54 \r
  55         #pragma aux portSWITCH_CONTEXT =        "mov    ax, seg pxCurrentTCB"                                                                                                           \\r
  56                                                                                 "mov    ds, ax"                                                                                                                                         \\r
  57                                                                                 "les    bx, pxCurrentTCB"                       /* Save the stack pointer into the TCB. */              \\r
  58                                                                                 "mov    es:0x2[ bx ], ss"                                                                                                                       \\r
  59                                                                                 "mov    es:[ bx ], sp"                                                                                                                          \\r
  60                                                                                 "call   vTaskSwitchContext"                     /* Perform the switch. */                                               \\r
  61                                                                                 "mov    ax, seg pxCurrentTCB"           /* Restore the stack pointer from the TCB. */   \\r
  62                                                                                 "mov    ds, ax"                                                                                                                                         \\r
  63                                                                                 "les    bx, dword ptr pxCurrentTCB"                                                                                                     \\r
  64                                                                                 "mov    ss, es:[ bx + 2 ]"                                                                                                                      \\r
  65                                                                                 "mov    sp, es:[ bx ]"                                                                                                                          \\r
  66                                                                                 "mov    bp, sp"                                         /* Prepair the bp register for the restoration of the SP in the compiler generated portion of the ISR */        \\r
  67                                                                                 "add    bp, 0x0002"\r
  68 \r
  69                                                                                 \r
  70 \r
  71         #pragma aux portFIRST_CONTEXT =         "mov    ax, seg pxCurrentTCB"                   \\r
  72                                                                                 "mov    ds, ax"                                                 \\r
  73                                                                                 "les    bx, dword ptr pxCurrentTCB"             \\r
  74                                                                                 "mov    ss, es:[ bx + 2 ]"                              \\r
  75                                                                                 "mov    sp, es:[ bx ]"                                  \\r
  76                                                                                 "add    sp, 0x0002"                                             /* Remove the extra bytes that exist in debug builds before restoring the context. */ \\r
  77                                                                                 "pop    ax"                                                             \\r
  78                                                                                 "pop    ax"                                                             \\r
  79                                                                                 "pop    es"                                                             \\r
  80                                                                                 "pop    ds"                                                             \\r
  81                                                                                 "popa"                                                                  \\r
  82                                                                                 "iret"                                                                  \r
  83 #else\r
  84 \r
  85         #pragma aux portSWITCH_CONTEXT =        "mov    ax, seg pxCurrentTCB"                                                                                                           \\r
  86                                                                                 "mov    ds, ax"                                                                                                                                         \\r
  87                                                                                 "les    bx, pxCurrentTCB"                       /* Save the stack pointer into the TCB. */              \\r
  88                                                                                 "mov    es:0x2[ bx ], ss"                                                                                                                       \\r
  89                                                                                 "mov    es:[ bx ], sp"                                                                                                                          \\r
  90                                                                                 "call   vTaskSwitchContext"                     /* Perform the switch. */                                               \\r
  91                                                                                 "mov    ax, seg pxCurrentTCB"           /* Restore the stack pointer from the TCB. */   \\r
  92                                                                                 "mov    ds, ax"                                                                                                                                         \\r
  93                                                                                 "les    bx, dword ptr pxCurrentTCB"                                                                                                     \\r
  94                                                                                 "mov    ss, es:[ bx + 2 ]"                                                                                                                      \\r
  95                                                                                 "mov    sp, es:[ bx ]"\r
  96                                                                                 \r
  97 \r
  98         #pragma aux portFIRST_CONTEXT =         "mov    ax, seg pxCurrentTCB"                   \\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                                                                                 "pop    ax"                                                             \\r
 104                                                                                 "pop    ax"                                                             \\r
 105                                                                                 "pop    es"                                                             \\r
 106                                                                                 "pop    ds"                                                             \\r
 107                                                                                 "popa"                                                                  \\r
 108                                                                                 "iret"                                                                  \r
 109 #endif\r
 110 \r
 111 \r