2 FreeRTOS V8.2.2 - Copyright (C) 2015 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 ***************************************************************************
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14 >>! NOTE: The modification to the GPL is included to allow you to !<<
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15 >>! distribute a combined work that includes FreeRTOS without being !<<
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16 >>! obliged to provide the source code for proprietary components !<<
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17 >>! outside of the FreeRTOS kernel. !<<
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18 ***************************************************************************
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20 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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21 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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22 FOR A PARTICULAR PURPOSE. Full license text is available on the following
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23 link: http://www.freertos.org/a00114.html
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25 ***************************************************************************
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27 * FreeRTOS provides completely free yet professionally developed, *
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28 * robust, strictly quality controlled, supported, and cross *
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29 * platform software that is more than just the market leader, it *
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30 * is the industry's de facto standard. *
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32 * Help yourself get started quickly while simultaneously helping *
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33 * to support the FreeRTOS project by purchasing a FreeRTOS *
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34 * tutorial book, reference manual, or both: *
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35 * http://www.FreeRTOS.org/Documentation *
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37 ***************************************************************************
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39 http://www.FreeRTOS.org/FAQHelp.html - Having a problem? Start by reading
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40 the FAQ page "My application does not run, what could be wrong?". Have you
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41 defined configASSERT()?
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43 http://www.FreeRTOS.org/support - In return for receiving this top quality
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44 embedded software for free we request you assist our global community by
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45 participating in the support forum.
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47 http://www.FreeRTOS.org/training - Investing in training allows your team to
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48 be as productive as possible as early as possible. Now you can receive
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49 FreeRTOS training directly from Richard Barry, CEO of Real Time Engineers
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50 Ltd, and the world's leading authority on the world's leading RTOS.
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52 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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53 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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54 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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56 http://www.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
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57 Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.
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59 http://www.OpenRTOS.com - Real Time Engineers ltd. license FreeRTOS to High
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60 Integrity Systems ltd. to sell under the OpenRTOS brand. Low cost OpenRTOS
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61 licenses offer ticketed support, indemnification and commercial middleware.
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63 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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64 engineered and independently SIL3 certified version for use in safety and
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65 mission critical applications that require provable dependability.
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70 #include "FreeRTOSConfig.h"
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72 #define portCONTEXT_SIZE 132
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73 #define portEPC_STACK_LOCATION 124
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74 #define portSTATUS_STACK_LOCATION 128
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76 #ifdef __LANGUAGE_ASSEMBLY__
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78 /******************************************************************/
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79 .macro portSAVE_CONTEXT
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81 /* Make room for the context. First save the current status so it can be
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82 manipulated, and the cause and EPC registers so their original values are
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85 addiu sp, sp, -portCONTEXT_SIZE
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86 mfc0 k1, _CP0_STATUS
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88 /* Also save s6 and s5 so they can be used. Any nesting interrupts should
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89 maintain the values of these registers across the ISR. */
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92 sw k1, portSTATUS_STACK_LOCATION(sp)
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94 /* Prepare to enable interrupts above the current priority.
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95 k0 = k0 >> 10. Moves RIPL[17:10] to [7:0] */
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98 /* Insert bit field. 7 bits k0[6:0] to k1[16:10] */
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101 /* Sets CP0.Status.IPL = CP0.Cause.RIPL
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102 Copy the MSB of the IPL, but it would be an error if it was set anyway. */
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105 /* MSB of IPL is bit[18] of CP0.Status */
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108 /* CP0.Status[5:1] = 0 b[5]=Rsvd, b[4]=UM,
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109 b[3]=Rsvd, b[2]=ERL, b[1]=EXL
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110 Setting EXL=0 allows higher priority interrupts
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111 to preempt this handler */
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115 /* s5 is used as the frame pointer. */
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118 /* Check the nesting count value. */
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119 la k0, uxInterruptNesting
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122 /* If the nesting count is 0 then swap to the the system stack, otherwise
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123 the system stack is already being used. */
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127 /* Swap to the system stack. */
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128 la sp, xISRStackTop
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131 /* Increment and save the nesting count. */
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135 /* s6 holds the EPC value, this is saved after interrupts are re-enabled. */
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138 /* Re-enable interrupts. */
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139 mtc0 k1, _CP0_STATUS
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141 /* Save the context into the space just created. s6 is saved again
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142 here as it now contains the EPC value. No other s registers need be
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144 sw ra, 120(s5) /* Return address (RA=R31) */
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145 sw s8, 116(s5) /* Frame Pointer (FP=R30) */
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162 sw s6, portEPC_STACK_LOCATION(s5)
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165 /* MEC14xx does not have DSP, removed 7 words */
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171 /* Update the task stack pointer value if nesting is zero. */
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172 la s6, uxInterruptNesting
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178 /* Save the stack pointer. */
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179 la s6, uxSavedTaskStackPointer
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184 /******************************************************************/
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185 .macro portRESTORE_CONTEXT
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187 /* Restore the stack pointer from the TCB. This is only done if the
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188 nesting count is 1. */
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189 la s6, uxInterruptNesting
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194 la s6, uxSavedTaskStackPointer
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197 /* Restore the context.
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198 MCHP MEC14xx does not include DSP */
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206 /* s6 is loaded as it was used as a scratch register and therefore saved
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207 as part of the interrupt context. */
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228 /* Protect access to the k registers, and others. */
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232 /* Decrement the nesting count. */
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233 la k0, uxInterruptNesting
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238 lw k0, portSTATUS_STACK_LOCATION(s5)
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239 lw k1, portEPC_STACK_LOCATION(s5)
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241 /* Leave the stack in its original state. First load sp from s5, then
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242 restore s5 from the stack. */
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245 addiu sp, sp, portCONTEXT_SIZE
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247 mtc0 k0, _CP0_STATUS
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255 #endif /* #ifdef __LANGUAGE_ASSEMBLY__ */
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