text: /*
   * FreeRTOS Kernel V10.2.0
   * Copyright (C) 2019 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy of
   * this software and associated documentation files (the "Software"), to deal in
   * the Software without restriction, including without limitation the rights to
   * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
   * the Software, and to permit persons to whom the Software is furnished to do so,
   * subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in all
   * copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
   * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
   * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
   * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   *
   * http://www.FreeRTOS.org
   * http://aws.amazon.com/freertos
   *
   * 1 tab == 4 spaces!
   */
  
  #ifndef PORT_ASM_H
  #define PORT_ASM_H
  
  typedef void TCB_t;
  extern volatile TCB_t * volatile pxCurrentTCB;
  extern void vTaskSwitchContext( void );
  
  /*
   * Saves the stack pointer for one task into its TCB, calls
   * vTaskSwitchContext() to update the TCB being used, then restores the stack
   * from the new TCB read to run the task.
   */
  void portSWITCH_CONTEXT( void );
  
  /*
   * Load the stack pointer from the TCB of the task which is going to be first
   * to execute.  Then force an IRET so the registers and IP are popped off the
   * stack.
   */
  void portFIRST_CONTEXT( void );
  
  /* There are slightly different versions depending on whether you are building
  to include debugger information.  If debugger information is used then there
  are a couple of extra bytes left of the ISR stack (presumably for use by the
  debugger).  The true stack pointer is then stored in the bp register.  We add
  2 to the stack pointer to remove the extra bytes before we restore our context. */
  
  #define portSWITCH_CONTEXT()											\
  							asm { mov	ax, seg pxCurrentTCB		}	\
  							asm { mov	ds, ax						}	\
  							asm { les	bx, pxCurrentTCB			}	/* Save the stack pointer into the TCB. */		\
  							asm { mov	es:0x2[ bx ], ss			}	\
  							asm { mov	es:[ bx ], sp				}	\
  							asm { call  far ptr vTaskSwitchContext	}	/* Perform the switch. */						\
  							asm { mov	ax, seg pxCurrentTCB		}	/* Restore the stack pointer from the TCB. */	\
  							asm { mov	ds, ax						}	\
  							asm { les	bx, dword ptr pxCurrentTCB	}	\
  							asm { mov	ss, es:[ bx + 2 ]			}	\
  							asm { mov	sp, es:[ bx ]				}
  
  #define portFIRST_CONTEXT()												\
  							__asm { mov	ax, seg pxCurrentTCB		}	\
  							__asm { mov	ds, ax						}	\
  							__asm { les	bx, dword ptr pxCurrentTCB	}	\
  							__asm { mov	ss, es:[ bx + 2 ]			}	\
  							__asm { mov	sp, es:[ bx ]				}	\
  							__asm { pop	bp							}	\
  							__asm { pop	di							}	\
  							__asm { pop	si							}	\
  							__asm { pop	ds							}	\
  							__asm { pop	es							}	\
  							__asm { pop	dx							}	\
  							__asm { pop	cx							}	\
  							__asm { pop	bx							}	\
  							__asm { pop	ax							}	\
  							__asm { iret							}
  
  
  #endif
  
  