2 FreeRTOS V8.2.0rc1 - Copyright (C) 2014 Real Time Engineers Ltd.
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5 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 This file is part of the FreeRTOS distribution.
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9 FreeRTOS is free software; you can redistribute it and/or modify it under
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10 the terms of the GNU General Public License (version 2) as published by the
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11 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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13 >>! NOTE: The modification to the GPL is included to allow you to !<<
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14 >>! distribute a combined work that includes FreeRTOS without being !<<
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15 >>! obliged to provide the source code for proprietary components !<<
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16 >>! outside of the FreeRTOS kernel. !<<
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18 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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19 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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20 FOR A PARTICULAR PURPOSE. Full license text is available on the following
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21 link: http://www.freertos.org/a00114.html
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25 ***************************************************************************
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27 * Having a problem? Start by reading the FAQ "My application does *
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28 * not run, what could be wrong?". Have you defined configASSERT()? *
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30 * http://www.FreeRTOS.org/FAQHelp.html *
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32 ***************************************************************************
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34 ***************************************************************************
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36 * FreeRTOS provides completely free yet professionally developed, *
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37 * robust, strictly quality controlled, supported, and cross *
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38 * platform software that is more than just the market leader, it *
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39 * is the industry's de facto standard. *
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41 * Help yourself get started quickly while simultaneously helping *
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42 * to support the FreeRTOS project by purchasing a FreeRTOS *
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43 * tutorial book, reference manual, or both: *
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44 * http://www.FreeRTOS.org/Documentation *
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46 ***************************************************************************
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48 ***************************************************************************
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50 * Investing in training allows your team to be as productive as *
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51 * possible as early as possible, lowering your overall development *
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52 * cost, and enabling you to bring a more robust product to market *
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53 * earlier than would otherwise be possible. Richard Barry is both *
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54 * the architect and key author of FreeRTOS, and so also the world's *
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55 * leading authority on what is the world's most popular real time *
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56 * kernel for deeply embedded MCU designs. Obtaining your training *
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57 * from Richard ensures your team will gain directly from his in-depth *
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58 * product knowledge and years of usage experience. Contact Real Time *
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59 * Engineers Ltd to enquire about the FreeRTOS Masterclass, presented *
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60 * by Richard Barry: http://www.FreeRTOS.org/contact
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62 ***************************************************************************
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64 ***************************************************************************
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66 * You are receiving this top quality software for free. Please play *
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67 * fair and reciprocate by reporting any suspected issues and *
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68 * participating in the community forum: *
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69 * http://www.FreeRTOS.org/support *
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73 ***************************************************************************
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75 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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76 license and Real Time Engineers Ltd. contact details.
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78 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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79 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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80 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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82 http://www.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
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83 Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.
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85 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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86 Integrity Systems ltd. to sell under the OpenRTOS brand. Low cost OpenRTOS
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87 licenses offer ticketed support, indemnification and commercial middleware.
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89 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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90 engineered and independently SIL3 certified version for use in safety and
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91 mission critical applications that require provable dependability.
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100 + AVR port - Replaced the inb() and outb() functions with direct memory
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101 access. This allows the port to be built with the 20050414 build of
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105 #include <stdlib.h>
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106 #include <avr/interrupt.h>
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108 #include "FreeRTOS.h"
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111 /*-----------------------------------------------------------
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112 * Implementation of functions defined in portable.h for the AVR port.
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113 *----------------------------------------------------------*/
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115 /* Start tasks with interrupts enables. */
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116 #define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x80 )
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118 /* Hardware constants for timer 1. */
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119 #define portCLEAR_COUNTER_ON_MATCH ( ( uint8_t ) 0x08 )
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120 #define portPRESCALE_64 ( ( uint8_t ) 0x03 )
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121 #define portCLOCK_PRESCALER ( ( uint32_t ) 64 )
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122 #define portCOMPARE_MATCH_A_INTERRUPT_ENABLE ( ( uint8_t ) 0x10 )
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124 /*-----------------------------------------------------------*/
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126 /* We require the address of the pxCurrentTCB variable, but don't want to know
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127 any details of its type. */
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128 typedef void TCB_t;
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129 extern volatile TCB_t * volatile pxCurrentTCB;
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131 /*-----------------------------------------------------------*/
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134 * Macro to save all the general purpose registers, the save the stack pointer
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137 * The first thing we do is save the flags then disable interrupts. This is to
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138 * guard our stack against having a context switch interrupt after we have already
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139 * pushed the registers onto the stack - causing the 32 registers to be on the
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142 * r1 is set to zero as the compiler expects it to be thus, however some
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143 * of the math routines make use of R1.
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145 * The interrupts will have been disabled during the call to portSAVE_CONTEXT()
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146 * so we need not worry about reading/writing to the stack pointer.
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149 #define portSAVE_CONTEXT() \
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150 asm volatile ( "push r0 \n\t" \
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151 "in r0, __SREG__ \n\t" \
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186 "lds r26, pxCurrentTCB \n\t" \
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187 "lds r27, pxCurrentTCB + 1 \n\t" \
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188 "in r0, 0x3d \n\t" \
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190 "in r0, 0x3e \n\t" \
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195 * Opposite to portSAVE_CONTEXT(). Interrupts will have been disabled during
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196 * the context save so we can write to the stack pointer.
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199 #define portRESTORE_CONTEXT() \
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200 asm volatile ( "lds r26, pxCurrentTCB \n\t" \
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201 "lds r27, pxCurrentTCB + 1 \n\t" \
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202 "ld r28, x+ \n\t" \
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203 "out __SP_L__, r28 \n\t" \
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204 "ld r29, x+ \n\t" \
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205 "out __SP_H__, r29 \n\t" \
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238 "out __SREG__, r0 \n\t" \
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242 /*-----------------------------------------------------------*/
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245 * Perform hardware setup to enable ticks from timer 1, compare match A.
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247 static void prvSetupTimerInterrupt( void );
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248 /*-----------------------------------------------------------*/
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251 * See header file for description.
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253 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
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255 uint16_t usAddress;
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257 /* Place a few bytes of known values on the bottom of the stack.
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258 This is just useful for debugging. */
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260 *pxTopOfStack = 0x11;
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262 *pxTopOfStack = 0x22;
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264 *pxTopOfStack = 0x33;
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267 /* Simulate how the stack would look after a call to vPortYield() generated by
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270 /*lint -e950 -e611 -e923 Lint doesn't like this much - but nothing I can do about it. */
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272 /* The start of the task code will be popped off the stack last, so place
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274 usAddress = ( uint16_t ) pxCode;
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275 *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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279 *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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282 /* Next simulate the stack as if after a call to portSAVE_CONTEXT().
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283 portSAVE_CONTEXT places the flags on the stack immediately after r0
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284 to ensure the interrupts get disabled as soon as possible, and so ensuring
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285 the stack use is minimal should a context switch interrupt occur. */
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286 *pxTopOfStack = ( StackType_t ) 0x00; /* R0 */
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288 *pxTopOfStack = portFLAGS_INT_ENABLED;
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292 /* Now the remaining registers. The compiler expects R1 to be 0. */
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293 *pxTopOfStack = ( StackType_t ) 0x00; /* R1 */
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295 *pxTopOfStack = ( StackType_t ) 0x02; /* R2 */
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297 *pxTopOfStack = ( StackType_t ) 0x03; /* R3 */
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299 *pxTopOfStack = ( StackType_t ) 0x04; /* R4 */
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301 *pxTopOfStack = ( StackType_t ) 0x05; /* R5 */
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303 *pxTopOfStack = ( StackType_t ) 0x06; /* R6 */
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305 *pxTopOfStack = ( StackType_t ) 0x07; /* R7 */
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307 *pxTopOfStack = ( StackType_t ) 0x08; /* R8 */
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309 *pxTopOfStack = ( StackType_t ) 0x09; /* R9 */
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311 *pxTopOfStack = ( StackType_t ) 0x10; /* R10 */
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313 *pxTopOfStack = ( StackType_t ) 0x11; /* R11 */
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315 *pxTopOfStack = ( StackType_t ) 0x12; /* R12 */
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317 *pxTopOfStack = ( StackType_t ) 0x13; /* R13 */
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319 *pxTopOfStack = ( StackType_t ) 0x14; /* R14 */
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321 *pxTopOfStack = ( StackType_t ) 0x15; /* R15 */
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323 *pxTopOfStack = ( StackType_t ) 0x16; /* R16 */
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325 *pxTopOfStack = ( StackType_t ) 0x17; /* R17 */
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327 *pxTopOfStack = ( StackType_t ) 0x18; /* R18 */
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329 *pxTopOfStack = ( StackType_t ) 0x19; /* R19 */
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331 *pxTopOfStack = ( StackType_t ) 0x20; /* R20 */
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333 *pxTopOfStack = ( StackType_t ) 0x21; /* R21 */
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335 *pxTopOfStack = ( StackType_t ) 0x22; /* R22 */
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337 *pxTopOfStack = ( StackType_t ) 0x23; /* R23 */
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340 /* Place the parameter on the stack in the expected location. */
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341 usAddress = ( uint16_t ) pvParameters;
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342 *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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346 *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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349 *pxTopOfStack = ( StackType_t ) 0x26; /* R26 X */
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351 *pxTopOfStack = ( StackType_t ) 0x27; /* R27 */
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353 *pxTopOfStack = ( StackType_t ) 0x28; /* R28 Y */
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355 *pxTopOfStack = ( StackType_t ) 0x29; /* R29 */
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357 *pxTopOfStack = ( StackType_t ) 0x30; /* R30 Z */
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359 *pxTopOfStack = ( StackType_t ) 0x031; /* R31 */
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362 /*lint +e950 +e611 +e923 */
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364 return pxTopOfStack;
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366 /*-----------------------------------------------------------*/
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368 BaseType_t xPortStartScheduler( void )
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370 /* Setup the hardware to generate the tick. */
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371 prvSetupTimerInterrupt();
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373 /* Restore the context of the first task that is going to run. */
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374 portRESTORE_CONTEXT();
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376 /* Simulate a function call end as generated by the compiler. We will now
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377 jump to the start of the task the context of which we have just restored. */
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378 asm volatile ( "ret" );
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380 /* Should not get here. */
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383 /*-----------------------------------------------------------*/
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385 void vPortEndScheduler( void )
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387 /* It is unlikely that the AVR port will get stopped. If required simply
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388 disable the tick interrupt here. */
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390 /*-----------------------------------------------------------*/
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393 * Manual context switch. The first thing we do is save the registers so we
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394 * can use a naked attribute.
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396 void vPortYield( void ) __attribute__ ( ( naked ) );
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397 void vPortYield( void )
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399 portSAVE_CONTEXT();
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400 vTaskSwitchContext();
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401 portRESTORE_CONTEXT();
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403 asm volatile ( "ret" );
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405 /*-----------------------------------------------------------*/
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408 * Context switch function used by the tick. This must be identical to
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409 * vPortYield() from the call to vTaskSwitchContext() onwards. The only
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410 * difference from vPortYield() is the tick count is incremented as the
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411 * call comes from the tick ISR.
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413 void vPortYieldFromTick( void ) __attribute__ ( ( naked ) );
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414 void vPortYieldFromTick( void )
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416 portSAVE_CONTEXT();
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417 if( xTaskIncrementTick() != pdFALSE )
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419 vTaskSwitchContext();
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421 portRESTORE_CONTEXT();
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423 asm volatile ( "ret" );
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425 /*-----------------------------------------------------------*/
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428 * Setup timer 1 compare match A to generate a tick interrupt.
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430 static void prvSetupTimerInterrupt( void )
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432 uint32_t ulCompareMatch;
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433 uint8_t ucHighByte, ucLowByte;
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435 /* Using 16bit timer 1 to generate the tick. Correct fuses must be
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436 selected for the configCPU_CLOCK_HZ clock. */
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438 ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
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440 /* We only have 16 bits so have to scale to get our required tick rate. */
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441 ulCompareMatch /= portCLOCK_PRESCALER;
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443 /* Adjust for correct value. */
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444 ulCompareMatch -= ( uint32_t ) 1;
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446 /* Setup compare match value for compare match A. Interrupts are disabled
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447 before this is called so we need not worry here. */
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448 ucLowByte = ( uint8_t ) ( ulCompareMatch & ( uint32_t ) 0xff );
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449 ulCompareMatch >>= 8;
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450 ucHighByte = ( uint8_t ) ( ulCompareMatch & ( uint32_t ) 0xff );
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451 OCR1AH = ucHighByte;
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452 OCR1AL = ucLowByte;
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454 /* Setup clock source and compare match behaviour. */
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455 ucLowByte = portCLEAR_COUNTER_ON_MATCH | portPRESCALE_64;
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456 TCCR1B = ucLowByte;
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458 /* Enable the interrupt - this is okay as interrupt are currently globally
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461 ucLowByte |= portCOMPARE_MATCH_A_INTERRUPT_ENABLE;
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464 /*-----------------------------------------------------------*/
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466 #if configUSE_PREEMPTION == 1
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469 * Tick ISR for preemptive scheduler. We can use a naked attribute as
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470 * the context is saved at the start of vPortYieldFromTick(). The tick
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471 * count is incremented after the context is saved.
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473 void SIG_OUTPUT_COMPARE1A( void ) __attribute__ ( ( signal, naked ) );
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474 void SIG_OUTPUT_COMPARE1A( void )
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476 vPortYieldFromTick();
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477 asm volatile ( "reti" );
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482 * Tick ISR for the cooperative scheduler. All this does is increment the
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483 * tick count. We don't need to switch context, this can only be done by
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484 * manual calls to taskYIELD();
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486 void SIG_OUTPUT_COMPARE1A( void ) __attribute__ ( ( signal ) );
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487 void SIG_OUTPUT_COMPARE1A( void )
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489 xTaskIncrementTick();
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projects / freertos / blob