/* FreeRTOS.org V5.1.1 - Copyright (C) 2003-2008 Richard Barry. This file is part of the FreeRTOS.org distribution. FreeRTOS.org is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. FreeRTOS.org 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. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA A special exception to the GPL can be applied should you wish to distribute a combined work that includes FreeRTOS.org, without being obliged to provide the source code for any proprietary components. See the licensing section of http://www.FreeRTOS.org for full details of how and when the exception can be applied. *************************************************************************** *************************************************************************** * * * SAVE TIME AND MONEY! We can port FreeRTOS.org to your own hardware, * * and even write all or part of your application on your behalf. * * See http://www.OpenRTOS.com for details of the services we provide to * * expedite your project. * * * *************************************************************************** *************************************************************************** Please ensure to read the configuration and relevant port sections of the online documentation. http://www.FreeRTOS.org - Documentation, latest information, license and contact details. http://www.SafeRTOS.com - A version that is certified for use in safety critical systems. http://www.OpenRTOS.com - Commercial support, development, porting, licensing and training services. */ /* GCC/HCS12 port by Jefferson L Smith, 2005 */ /* Scheduler includes. */ #include "FreeRTOS.h" #include "task.h" /* Port includes */ #include /*----------------------------------------------------------- * Implementation of functions defined in portable.h for the HCS12 port. *----------------------------------------------------------*/ /* * Configure a timer to generate the RTOS tick at the frequency specified * within FreeRTOSConfig.h. */ static void prvSetupTimerInterrupt( void ); /* NOTE: Interrupt service routines must be in non-banked memory - as does the scheduler startup function. */ #define ATTR_NEAR __attribute__((near)) /* Manual context switch function. This is the SWI ISR. */ // __attribute__((interrupt)) void ATTR_NEAR vPortYield( void ); /* Tick context switch function. This is the timer ISR. */ // __attribute__((interrupt)) void ATTR_NEAR vPortTickInterrupt( void ); /* Function in non-banked memory which actually switches to first task. */ portBASE_TYPE ATTR_NEAR xStartSchedulerNear( void ); /* Calls to portENTER_CRITICAL() can be nested. When they are nested the critical section should not be left (i.e. interrupts should not be re-enabled) until the nesting depth reaches 0. This variable simply tracks the nesting depth. Each task maintains it's own critical nesting depth variable so uxCriticalNesting is saved and restored from the task stack during a context switch. */ volatile unsigned portBASE_TYPE uxCriticalNesting = 0x80; // un-initialized /*-----------------------------------------------------------*/ /* * See header file for description. */ portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters ) { /* Setup the initial stack of the task. The stack is set exactly as expected by the portRESTORE_CONTEXT() macro. In this case the stack as expected by the HCS12 RTI instruction. */ /* The address of the task function is placed in the stack byte at a time. */ *pxTopOfStack = ( portSTACK_TYPE ) *( ((portSTACK_TYPE *) (&pxCode) ) + 1 ); *--pxTopOfStack = ( portSTACK_TYPE ) *( ((portSTACK_TYPE *) (&pxCode) ) + 0 ); /* Next are all the registers that form part of the task context. */ /* Y register */ *--pxTopOfStack = ( portSTACK_TYPE ) 0xff; *--pxTopOfStack = ( portSTACK_TYPE ) 0xee; /* X register */ *--pxTopOfStack = ( portSTACK_TYPE ) 0xdd; *--pxTopOfStack = ( portSTACK_TYPE ) 0xcc; /* A register contains parameter high byte. */ *--pxTopOfStack = ( portSTACK_TYPE ) *( ((portSTACK_TYPE *) (&pvParameters) ) + 0 ); /* B register contains parameter low byte. */ *--pxTopOfStack = ( portSTACK_TYPE ) *( ((portSTACK_TYPE *) (&pvParameters) ) + 1 ); /* CCR: Note that when the task starts interrupts will be enabled since "I" bit of CCR is cleared */ *--pxTopOfStack = ( portSTACK_TYPE ) 0x80; // keeps Stop disabled (MCU default) /* tmp softregs used by GCC. Values right now don't matter. */ __asm("\n\ movw _.frame, 2,-%0 \n\ movw _.tmp, 2,-%0 \n\ movw _.z, 2,-%0 \n\ movw _.xy, 2,-%0 \n\ ;movw _.d2, 2,-%0 \n\ ;movw _.d1, 2,-%0 \n\ ": "=A"(pxTopOfStack) : "0"(pxTopOfStack) ); #ifdef BANKED_MODEL /* The page of the task. */ *--pxTopOfStack = 0x30; // can only directly start in PPAGE 0x30 #endif /* The critical nesting depth is initialised with 0 (meaning not in a critical section). */ *--pxTopOfStack = ( portSTACK_TYPE ) 0x00; return pxTopOfStack; } /*-----------------------------------------------------------*/ void vPortEndScheduler( void ) { /* It is unlikely that the HCS12 port will get stopped. */ } /*-----------------------------------------------------------*/ static void prvSetupTimerInterrupt( void ) { /* Enable hardware RTI timer */ /* Ignores configTICK_RATE_HZ */ RTICTL = 0x50; // 16 MHz xtal: 976.56 Hz, 1024mS CRGINT |= 0x80; // RTIE } /*-----------------------------------------------------------*/ portBASE_TYPE xPortStartScheduler( void ) { /* xPortStartScheduler() does not start the scheduler directly because the header file containing the xPortStartScheduler() prototype is part of the common kernel code, and therefore cannot use the CODE_SEG pragma. Instead it simply calls the locally defined xNearStartScheduler() - which does use the CODE_SEG pragma. */ short register d; __asm ("jmp xStartSchedulerNear ; will never return": "=d"(d)); return d; } /*-----------------------------------------------------------*/ portBASE_TYPE xStartSchedulerNear( void ) { /* Configure the timer that will generate the RTOS tick. Interrupts are disabled when this function is called. */ prvSetupTimerInterrupt(); /* Restore the context of the first task. */ portRESTORE_CONTEXT(); portISR_TAIL(); /* Should not get here! */ return pdFALSE; } /*-----------------------------------------------------------*/ /* * Context switch functions. These are interrupt service routines. */ /* * Manual context switch forced by calling portYIELD(). This is the SWI * handler. */ void vPortYield( void ) { portISR_HEAD(); /* NOTE: This is the trap routine (swi) although not defined as a trap. It will fill the stack the same way as an ISR in order to mix preemtion and cooperative yield. */ portSAVE_CONTEXT(); vTaskSwitchContext(); portRESTORE_CONTEXT(); portISR_TAIL(); } /*-----------------------------------------------------------*/ /* * RTOS tick interrupt service routine. If the cooperative scheduler is * being used then this simply increments the tick count. If the * preemptive scheduler is being used a context switch can occur. */ void vPortTickInterrupt( void ) { portISR_HEAD(); /* Clear tick timer flag */ CRGFLG = 0x80; #if configUSE_PREEMPTION == 1 { /* A context switch might happen so save the context. */ portSAVE_CONTEXT(); /* Increment the tick ... */ vTaskIncrementTick(); /* ... then see if the new tick value has necessitated a context switch. */ vTaskSwitchContext(); /* Restore the context of a task - which may be a different task to that interrupted. */ portRESTORE_CONTEXT(); } #else { vTaskIncrementTick(); } #endif portISR_TAIL(); }