/*
    FreeRTOS V8.0.1 - Copyright (C) 2014 Real Time Engineers Ltd. 
    All rights reserved

    VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

    ***************************************************************************
     *                                                                       *
     *    FreeRTOS provides completely free yet professionally developed,    *
     *    robust, strictly quality controlled, supported, and cross          *
     *    platform software that has become a de facto standard.             *
     *                                                                       *
     *    Help yourself get started quickly and support the FreeRTOS         *
     *    project by purchasing a FreeRTOS tutorial book, reference          *
     *    manual, or both from: http://www.FreeRTOS.org/Documentation        *
     *                                                                       *
     *    Thank you!                                                         *
     *                                                                       *
    ***************************************************************************

    This file is part of the FreeRTOS distribution.

    FreeRTOS is free software; you can redistribute it and/or modify it under
    the terms of the GNU General Public License (version 2) as published by the
    Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.

    >>!   NOTE: The modification to the GPL is included to allow you to     !<<
    >>!   distribute a combined work that includes FreeRTOS without being   !<<
    >>!   obliged to provide the source code for proprietary components     !<<
    >>!   outside of the FreeRTOS kernel.                                   !<<

    FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    FOR A PARTICULAR PURPOSE.  Full license text is available from the following
    link: http://www.freertos.org/a00114.html

    1 tab == 4 spaces!

    ***************************************************************************
     *                                                                       *
     *    Having a problem?  Start by reading the FAQ "My application does   *
     *    not run, what could be wrong?"                                     *
     *                                                                       *
     *    http://www.FreeRTOS.org/FAQHelp.html                               *
     *                                                                       *
    ***************************************************************************

    http://www.FreeRTOS.org - Documentation, books, training, latest versions,
    license and Real Time Engineers Ltd. contact details.

    http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
    including FreeRTOS+Trace - an indispensable productivity tool, a DOS
    compatible FAT file system, and our tiny thread aware UDP/IP stack.

    http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
    Integrity Systems to sell under the OpenRTOS brand.  Low cost OpenRTOS
    licenses offer ticketed support, indemnification and middleware.

    http://www.SafeRTOS.com - High Integrity Systems also provide a safety
    engineered and independently SIL3 certified version for use in safety and
    mission critical applications that require provable dependability.

    1 tab == 4 spaces!
*/

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. */

#ifdef DEBUG_BUILD

	#pragma aux portSWITCH_CONTEXT =	"mov	ax, seg pxCurrentTCB"														\
										"mov	ds, ax"																		\
										"les	bx, pxCurrentTCB"			/* Save the stack pointer into the TCB. */		\
										"mov	es:0x2[ bx ], ss"															\
										"mov	es:[ bx ], sp"																\
										"call	vTaskSwitchContext"			/* Perform the switch. */						\
										"mov	ax, seg pxCurrentTCB"		/* Restore the stack pointer from the TCB. */	\
										"mov	ds, ax"																		\
										"les	bx, dword ptr pxCurrentTCB"													\
										"mov	ss, es:[ bx + 2 ]"															\
										"mov	sp, es:[ bx ]"																\
										"mov	bp, sp"						/* Prepair the bp register for the restoration of the SP in the compiler generated portion of the ISR */	\
										"add	bp, 0x0002"

										

	#pragma aux portFIRST_CONTEXT =		"mov	ax, seg pxCurrentTCB"			\
										"mov	ds, ax"							\
										"les	bx, dword ptr pxCurrentTCB"		\
										"mov	ss, es:[ bx + 2 ]"				\
										"mov	sp, es:[ bx ]"					\
										"add	sp, 0x0002"						/* Remove the extra bytes that exist in debug builds before restoring the context. */ \
										"pop	ax"								\
										"pop	ax"								\
										"pop	es"								\
										"pop	ds"								\
										"popa"									\
										"iret"									
#else

	#pragma aux portSWITCH_CONTEXT =	"mov	ax, seg pxCurrentTCB"														\
										"mov	ds, ax"																		\
										"les	bx, pxCurrentTCB"			/* Save the stack pointer into the TCB. */		\
										"mov	es:0x2[ bx ], ss"															\
										"mov	es:[ bx ], sp"																\
										"call	vTaskSwitchContext"			/* Perform the switch. */						\
										"mov	ax, seg pxCurrentTCB"		/* Restore the stack pointer from the TCB. */	\
										"mov	ds, ax"																		\
										"les	bx, dword ptr pxCurrentTCB"													\
										"mov	ss, es:[ bx + 2 ]"															\
										"mov	sp, es:[ bx ]"
										

	#pragma aux portFIRST_CONTEXT =		"mov	ax, seg pxCurrentTCB"			\
										"mov	ds, ax"							\
										"les	bx, dword ptr pxCurrentTCB"		\
										"mov	ss, es:[ bx + 2 ]"				\
										"mov	sp, es:[ bx ]"					\
										"pop	ax"								\
										"pop	ax"								\
										"pop	es"								\
										"pop	ds"								\
										"popa"									\
										"iret"									
#endif


