begriffs open source - freertos/blob - portable/oWatcom/16BitDOS/common/portasm.h

   1 /*
   2  * FreeRTOS SMP Kernel V202110.00
   3  * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a copy of
   6  * this software and associated documentation files (the "Software"), to deal in
   7  * the Software without restriction, including without limitation the rights to
   8  * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
   9  * the Software, and to permit persons to whom the Software is furnished to do so,
  10  * subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be included in all
  13  * copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
  17  * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
  18  * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
  19  * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  20  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  21  *
  22  * https://www.FreeRTOS.org
  23  * https://github.com/FreeRTOS
  24  *
  25  * 1 tab == 4 spaces!
  26  */
  27
  28 typedef void TCB_t;
  29 extern volatile TCB_t * volatile pxCurrentTCB;
  30 extern void vTaskSwitchContext( void );
  31
  32 /*
  33  * Saves the stack pointer for one task into its TCB, calls
  34  * vTaskSwitchContext() to update the TCB being used, then restores the stack
  35  * from the new TCB read to run the task.
  36  */
  37 void portSWITCH_CONTEXT( void );
  38
  39 /*
  40  * Load the stack pointer from the TCB of the task which is going to be first
  41  * to execute.  Then force an IRET so the registers and IP are popped off the
  42  * stack.
  43  */
  44 void portFIRST_CONTEXT( void );
  45
  46 /* There are slightly different versions depending on whether you are building
  47 to include debugger information.  If debugger information is used then there
  48 are a couple of extra bytes left of the ISR stack (presumably for use by the
  49 debugger).  The true stack pointer is then stored in the bp register.  We add
  50 2 to the stack pointer to remove the extra bytes before we restore our context. */
  51
  52 #ifdef DEBUG_BUILD
  53
  54         #pragma aux portSWITCH_CONTEXT =        "mov    ax, seg pxCurrentTCB"                                                                                                           \
  55                                                                                 "mov    ds, ax"                                                                                                                                         \
  56                                                                                 "les    bx, pxCurrentTCB"                       /* Save the stack pointer into the TCB. */              \
  57                                                                                 "mov    es:0x2[ bx ], ss"                                                                                                                       \
  58                                                                                 "mov    es:[ bx ], sp"                                                                                                                          \
  59                                                                                 "call   vTaskSwitchContext"                     /* Perform the switch. */                                               \
  60                                                                                 "mov    ax, seg pxCurrentTCB"           /* Restore the stack pointer from the TCB. */   \
  61                                                                                 "mov    ds, ax"                                                                                                                                         \
  62                                                                                 "les    bx, dword ptr pxCurrentTCB"                                                                                                     \
  63                                                                                 "mov    ss, es:[ bx + 2 ]"                                                                                                                      \
  64                                                                                 "mov    sp, es:[ bx ]"                                                                                                                          \
  65                                                                                 "mov    bp, sp"                                         /* Prepair the bp register for the restoration of the SP in the compiler generated portion of the ISR */        \
  66                                                                                 "add    bp, 0x0002"
  67
  68
  69
  70         #pragma aux portFIRST_CONTEXT =         "mov    ax, seg pxCurrentTCB"                   \
  71                                                                                 "mov    ds, ax"                                                 \
  72                                                                                 "les    bx, dword ptr pxCurrentTCB"             \
  73                                                                                 "mov    ss, es:[ bx + 2 ]"                              \
  74                                                                                 "mov    sp, es:[ bx ]"                                  \
  75                                                                                 "add    sp, 0x0002"                                             /* Remove the extra bytes that exist in debug builds before restoring the context. */ \
  76                                                                                 "pop    ax"                                                             \
  77                                                                                 "pop    ax"                                                             \
  78                                                                                 "pop    es"                                                             \
  79                                                                                 "pop    ds"                                                             \
  80                                                                                 "popa"                                                                  \
  81                                                                                 "iret"
  82 #else
  83
  84         #pragma aux portSWITCH_CONTEXT =        "mov    ax, seg pxCurrentTCB"                                                                                                           \
  85                                                                                 "mov    ds, ax"                                                                                                                                         \
  86                                                                                 "les    bx, pxCurrentTCB"                       /* Save the stack pointer into the TCB. */              \
  87                                                                                 "mov    es:0x2[ bx ], ss"                                                                                                                       \
  88                                                                                 "mov    es:[ bx ], sp"                                                                                                                          \
  89                                                                                 "call   vTaskSwitchContext"                     /* Perform the switch. */                                               \
  90                                                                                 "mov    ax, seg pxCurrentTCB"           /* Restore the stack pointer from the TCB. */   \
  91                                                                                 "mov    ds, ax"                                                                                                                                         \
  92                                                                                 "les    bx, dword ptr pxCurrentTCB"                                                                                                     \
  93                                                                                 "mov    ss, es:[ bx + 2 ]"                                                                                                                      \
  94                                                                                 "mov    sp, es:[ bx ]"
  95
  96
  97         #pragma aux portFIRST_CONTEXT =         "mov    ax, seg pxCurrentTCB"                   \
  98                                                                                 "mov    ds, ax"                                                 \
  99                                                                                 "les    bx, dword ptr pxCurrentTCB"             \
 100                                                                                 "mov    ss, es:[ bx + 2 ]"                              \
 101                                                                                 "mov    sp, es:[ bx ]"                                  \
 102                                                                                 "pop    ax"                                                             \
 103                                                                                 "pop    ax"                                                             \
 104                                                                                 "pop    es"                                                             \
 105                                                                                 "pop    ds"                                                             \
 106                                                                                 "popa"                                                                  \
 107                                                                                 "iret"
 108 #endif
 109
 110