/* FreeRTOS V7.5.1 - Copyright (C) 2013 Real Time Engineers Ltd. 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! */ /* Changes from V2.6.0 + AVR port - Replaced the inb() and outb() functions with direct memory access. This allows the port to be built with the 20050414 build of WinAVR. */ #include #include #include "FreeRTOS.h" #include "task.h" /*----------------------------------------------------------- * Implementation of functions defined in portable.h for the AVR port. *----------------------------------------------------------*/ /* Start tasks with interrupts enables. */ #define portFLAGS_INT_ENABLED ( ( portSTACK_TYPE ) 0x80 ) /* Hardware constants for timer 1. */ #define portCLEAR_COUNTER_ON_MATCH ( ( unsigned char ) 0x08 ) #define portPRESCALE_64 ( ( unsigned char ) 0x03 ) #define portCLOCK_PRESCALER ( ( unsigned long ) 64 ) #define portCOMPARE_MATCH_A_INTERRUPT_ENABLE ( ( unsigned char ) 0x10 ) /*-----------------------------------------------------------*/ /* We require the address of the pxCurrentTCB variable, but don't want to know any details of its type. */ typedef void tskTCB; extern volatile tskTCB * volatile pxCurrentTCB; /*-----------------------------------------------------------*/ /* * Macro to save all the general purpose registers, the save the stack pointer * into the TCB. * * The first thing we do is save the flags then disable interrupts. This is to * guard our stack against having a context switch interrupt after we have already * pushed the registers onto the stack - causing the 32 registers to be on the * stack twice. * * r1 is set to zero as the compiler expects it to be thus, however some * of the math routines make use of R1. * * The interrupts will have been disabled during the call to portSAVE_CONTEXT() * so we need not worry about reading/writing to the stack pointer. */ #define portSAVE_CONTEXT() \ asm volatile ( "push r0 \n\t" \ "in r0, __SREG__ \n\t" \ "cli \n\t" \ "push r0 \n\t" \ "push r1 \n\t" \ "clr r1 \n\t" \ "push r2 \n\t" \ "push r3 \n\t" \ "push r4 \n\t" \ "push r5 \n\t" \ "push r6 \n\t" \ "push r7 \n\t" \ "push r8 \n\t" \ "push r9 \n\t" \ "push r10 \n\t" \ "push r11 \n\t" \ "push r12 \n\t" \ "push r13 \n\t" \ "push r14 \n\t" \ "push r15 \n\t" \ "push r16 \n\t" \ "push r17 \n\t" \ "push r18 \n\t" \ "push r19 \n\t" \ "push r20 \n\t" \ "push r21 \n\t" \ "push r22 \n\t" \ "push r23 \n\t" \ "push r24 \n\t" \ "push r25 \n\t" \ "push r26 \n\t" \ "push r27 \n\t" \ "push r28 \n\t" \ "push r29 \n\t" \ "push r30 \n\t" \ "push r31 \n\t" \ "lds r26, pxCurrentTCB \n\t" \ "lds r27, pxCurrentTCB + 1 \n\t" \ "in r0, 0x3d \n\t" \ "st x+, r0 \n\t" \ "in r0, 0x3e \n\t" \ "st x+, r0 \n\t" \ ); /* * Opposite to portSAVE_CONTEXT(). Interrupts will have been disabled during * the context save so we can write to the stack pointer. */ #define portRESTORE_CONTEXT() \ asm volatile ( "lds r26, pxCurrentTCB \n\t" \ "lds r27, pxCurrentTCB + 1 \n\t" \ "ld r28, x+ \n\t" \ "out __SP_L__, r28 \n\t" \ "ld r29, x+ \n\t" \ "out __SP_H__, r29 \n\t" \ "pop r31 \n\t" \ "pop r30 \n\t" \ "pop r29 \n\t" \ "pop r28 \n\t" \ "pop r27 \n\t" \ "pop r26 \n\t" \ "pop r25 \n\t" \ "pop r24 \n\t" \ "pop r23 \n\t" \ "pop r22 \n\t" \ "pop r21 \n\t" \ "pop r20 \n\t" \ "pop r19 \n\t" \ "pop r18 \n\t" \ "pop r17 \n\t" \ "pop r16 \n\t" \ "pop r15 \n\t" \ "pop r14 \n\t" \ "pop r13 \n\t" \ "pop r12 \n\t" \ "pop r11 \n\t" \ "pop r10 \n\t" \ "pop r9 \n\t" \ "pop r8 \n\t" \ "pop r7 \n\t" \ "pop r6 \n\t" \ "pop r5 \n\t" \ "pop r4 \n\t" \ "pop r3 \n\t" \ "pop r2 \n\t" \ "pop r1 \n\t" \ "pop r0 \n\t" \ "out __SREG__, r0 \n\t" \ "pop r0 \n\t" \ ); /*-----------------------------------------------------------*/ /* * Perform hardware setup to enable ticks from timer 1, compare match A. */ static void prvSetupTimerInterrupt( void ); /*-----------------------------------------------------------*/ /* * See header file for description. */ portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters ) { unsigned short usAddress; /* Place a few bytes of known values on the bottom of the stack. This is just useful for debugging. */ *pxTopOfStack = 0x11; pxTopOfStack--; *pxTopOfStack = 0x22; pxTopOfStack--; *pxTopOfStack = 0x33; pxTopOfStack--; /* Simulate how the stack would look after a call to vPortYield() generated by the compiler. */ /*lint -e950 -e611 -e923 Lint doesn't like this much - but nothing I can do about it. */ /* The start of the task code will be popped off the stack last, so place it on first. */ usAddress = ( unsigned short ) pxCode; *pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned short ) 0x00ff ); pxTopOfStack--; usAddress >>= 8; *pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned short ) 0x00ff ); pxTopOfStack--; /* Next simulate the stack as if after a call to portSAVE_CONTEXT(). portSAVE_CONTEXT places the flags on the stack immediately after r0 to ensure the interrupts get disabled as soon as possible, and so ensuring the stack use is minimal should a context switch interrupt occur. */ *pxTopOfStack = ( portSTACK_TYPE ) 0x00; /* R0 */ pxTopOfStack--; *pxTopOfStack = portFLAGS_INT_ENABLED; pxTopOfStack--; /* Now the remaining registers. The compiler expects R1 to be 0. */ *pxTopOfStack = ( portSTACK_TYPE ) 0x00; /* R1 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x02; /* R2 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x03; /* R3 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x04; /* R4 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x05; /* R5 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x06; /* R6 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x07; /* R7 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x08; /* R8 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x09; /* R9 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x10; /* R10 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x11; /* R11 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x12; /* R12 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x13; /* R13 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x14; /* R14 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x15; /* R15 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x16; /* R16 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x17; /* R17 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x18; /* R18 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x19; /* R19 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x20; /* R20 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x21; /* R21 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x22; /* R22 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x23; /* R23 */ pxTopOfStack--; /* Place the parameter on the stack in the expected location. */ usAddress = ( unsigned short ) pvParameters; *pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned short ) 0x00ff ); pxTopOfStack--; usAddress >>= 8; *pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned short ) 0x00ff ); pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x26; /* R26 X */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x27; /* R27 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x28; /* R28 Y */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x29; /* R29 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x30; /* R30 Z */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x031; /* R31 */ pxTopOfStack--; /*lint +e950 +e611 +e923 */ return pxTopOfStack; } /*-----------------------------------------------------------*/ portBASE_TYPE xPortStartScheduler( void ) { /* Setup the hardware to generate the tick. */ prvSetupTimerInterrupt(); /* Restore the context of the first task that is going to run. */ portRESTORE_CONTEXT(); /* Simulate a function call end as generated by the compiler. We will now jump to the start of the task the context of which we have just restored. */ asm volatile ( "ret" ); /* Should not get here. */ return pdTRUE; } /*-----------------------------------------------------------*/ void vPortEndScheduler( void ) { /* It is unlikely that the AVR port will get stopped. If required simply disable the tick interrupt here. */ } /*-----------------------------------------------------------*/ /* * Manual context switch. The first thing we do is save the registers so we * can use a naked attribute. */ void vPortYield( void ) __attribute__ ( ( naked ) ); void vPortYield( void ) { portSAVE_CONTEXT(); vTaskSwitchContext(); portRESTORE_CONTEXT(); asm volatile ( "ret" ); } /*-----------------------------------------------------------*/ /* * Context switch function used by the tick. This must be identical to * vPortYield() from the call to vTaskSwitchContext() onwards. The only * difference from vPortYield() is the tick count is incremented as the * call comes from the tick ISR. */ void vPortYieldFromTick( void ) __attribute__ ( ( naked ) ); void vPortYieldFromTick( void ) { portSAVE_CONTEXT(); if( xTaskIncrementTick() != pdFALSE ) { vTaskSwitchContext(); } portRESTORE_CONTEXT(); asm volatile ( "ret" ); } /*-----------------------------------------------------------*/ /* * Setup timer 1 compare match A to generate a tick interrupt. */ static void prvSetupTimerInterrupt( void ) { unsigned long ulCompareMatch; unsigned char ucHighByte, ucLowByte; /* Using 16bit timer 1 to generate the tick. Correct fuses must be selected for the configCPU_CLOCK_HZ clock. */ ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ; /* We only have 16 bits so have to scale to get our required tick rate. */ ulCompareMatch /= portCLOCK_PRESCALER; /* Adjust for correct value. */ ulCompareMatch -= ( unsigned long ) 1; /* Setup compare match value for compare match A. Interrupts are disabled before this is called so we need not worry here. */ ucLowByte = ( unsigned char ) ( ulCompareMatch & ( unsigned long ) 0xff ); ulCompareMatch >>= 8; ucHighByte = ( unsigned char ) ( ulCompareMatch & ( unsigned long ) 0xff ); OCR1AH = ucHighByte; OCR1AL = ucLowByte; /* Setup clock source and compare match behaviour. */ ucLowByte = portCLEAR_COUNTER_ON_MATCH | portPRESCALE_64; TCCR1B = ucLowByte; /* Enable the interrupt - this is okay as interrupt are currently globally disabled. */ ucLowByte = TIMSK; ucLowByte |= portCOMPARE_MATCH_A_INTERRUPT_ENABLE; TIMSK = ucLowByte; } /*-----------------------------------------------------------*/ #if configUSE_PREEMPTION == 1 /* * Tick ISR for preemptive scheduler. We can use a naked attribute as * the context is saved at the start of vPortYieldFromTick(). The tick * count is incremented after the context is saved. */ void SIG_OUTPUT_COMPARE1A( void ) __attribute__ ( ( signal, naked ) ); void SIG_OUTPUT_COMPARE1A( void ) { vPortYieldFromTick(); asm volatile ( "reti" ); } #else /* * Tick ISR for the cooperative scheduler. All this does is increment the * tick count. We don't need to switch context, this can only be done by * manual calls to taskYIELD(); */ void SIG_OUTPUT_COMPARE1A( void ) __attribute__ ( ( signal ) ); void SIG_OUTPUT_COMPARE1A( void ) { xTaskIncrementTick(); } #endif