2 FreeRTOS V8.1.1 - 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 ***************************************************************************
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9 * FreeRTOS provides completely free yet professionally developed, *
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10 * robust, strictly quality controlled, supported, and cross *
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11 * platform software that has become a de facto standard. *
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13 * Help yourself get started quickly and support the FreeRTOS *
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14 * project by purchasing a FreeRTOS tutorial book, reference *
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15 * manual, or both from: http://www.FreeRTOS.org/Documentation *
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19 ***************************************************************************
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21 This file is part of the FreeRTOS distribution.
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23 FreeRTOS is free software; you can redistribute it and/or modify it under
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24 the terms of the GNU General Public License (version 2) as published by the
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25 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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27 >>! NOTE: The modification to the GPL is included to allow you to !<<
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28 >>! distribute a combined work that includes FreeRTOS without being !<<
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29 >>! obliged to provide the source code for proprietary components !<<
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30 >>! outside of the FreeRTOS kernel. !<<
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32 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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33 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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34 FOR A PARTICULAR PURPOSE. Full license text is available from the following
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35 link: http://www.freertos.org/a00114.html
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39 ***************************************************************************
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41 * Having a problem? Start by reading the FAQ "My application does *
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42 * not run, what could be wrong?" *
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44 * http://www.FreeRTOS.org/FAQHelp.html *
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46 ***************************************************************************
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48 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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49 license and Real Time Engineers Ltd. contact details.
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51 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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52 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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53 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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55 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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56 Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
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57 licenses offer ticketed support, indemnification and middleware.
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59 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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60 engineered and independently SIL3 certified version for use in safety and
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61 mission critical applications that require provable dependability.
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67 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR USART1.
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69 ***Note*** This example uses queues to send each character into an interrupt
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70 service routine and out of an interrupt service routine individually. This
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71 is done to demonstrate queues being used in an interrupt, and to deliberately
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72 load the system to test the FreeRTOS port. It is *NOT* meant to be an
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73 example of an efficient implementation. An efficient implementation should
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74 use FIFO's or DMA if available, and only use FreeRTOS API functions when
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75 enough has been received to warrant a task being unblocked to process the
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79 /* Scheduler includes. */
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80 #include "FreeRTOS.h"
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83 #include "comtest2.h"
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85 /* Library includes. */
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88 /* Demo application includes. */
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89 #include "demo_serial.h"
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90 /*-----------------------------------------------------------*/
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93 #define serINVALID_QUEUE ( ( QueueHandle_t ) 0 )
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94 #define serNO_BLOCK ( ( TickType_t ) 0 )
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95 #define serPMC_USART_ID ( BOARD_ID_USART )
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97 /* The USART supported by this file. */
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98 #define serUSART_PORT ( USART1 )
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99 #define serUSART_IRQ ( USART1_IRQn )
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101 /* Every bit in the interrupt mask. */
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102 #define serMASK_ALL_INTERRUPTS ( 0xffffffffUL )
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104 /*-----------------------------------------------------------*/
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106 /* The queue used to hold received characters. */
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107 static QueueHandle_t xRxedChars;
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108 static QueueHandle_t xCharsForTx;
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110 /*-----------------------------------------------------------*/
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114 * See the serial.h header file.
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116 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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119 xComPortHandle xReturn;
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120 const sam_usart_opt_t xUSARTSettings =
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125 US_MR_NBSTOP_1_BIT,
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126 US_MR_CHMODE_NORMAL,
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127 0 /* Only used in IrDA mode. */
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130 /* Create the queues used to hold Rx/Tx characters. */
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131 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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132 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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134 /* If the queues were created correctly then setup the serial port
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136 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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138 /* Enable the peripheral clock in the PMC. */
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139 pmc_enable_periph_clk( serPMC_USART_ID );
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141 /* Configure USART in serial mode. */
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142 usart_init_rs232( serUSART_PORT, &xUSARTSettings, sysclk_get_cpu_hz() );
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144 /* Disable all the interrupts. */
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145 usart_disable_interrupt( serUSART_PORT, serMASK_ALL_INTERRUPTS );
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147 /* Enable the receiver and transmitter. */
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148 usart_enable_tx( serUSART_PORT );
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149 usart_enable_rx( serUSART_PORT );
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151 /* Clear any characters before enabling interrupt. */
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152 usart_getchar( serUSART_PORT, &ulChar );
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154 /* Enable Rx end interrupt. */
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155 usart_enable_interrupt( serUSART_PORT, US_IER_RXRDY );
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157 /* Configure and enable interrupt of USART. */
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158 NVIC_SetPriority( serUSART_IRQ, configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY );
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159 NVIC_EnableIRQ( serUSART_IRQ );
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163 xReturn = ( xComPortHandle ) 0;
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166 /* This demo file only supports a single port but we have to return
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167 something to comply with the standard demo header file. */
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170 /*-----------------------------------------------------------*/
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172 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime )
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174 /* The port handle is not required as this driver only supports one port. */
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177 /* Get the next character from the buffer. Return false if no characters
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178 are available, or arrive before xBlockTime expires. */
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179 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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188 /*-----------------------------------------------------------*/
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190 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
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192 signed char *pxNext;
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194 /* A couple of parameters that this port does not use. */
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195 ( void ) usStringLength;
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198 /* NOTE: This implementation does not handle the queue being full as no
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199 block time is used! */
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201 /* The port handle is not required as this driver only supports USART1. */
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204 /* Send each character in the string, one at a time. */
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205 pxNext = ( signed char * ) pcString;
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208 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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212 /*-----------------------------------------------------------*/
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214 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t xBlockTime )
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216 signed portBASE_TYPE xReturn;
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218 /* This simple example only supports one port. */
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221 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) == pdPASS )
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224 usart_enable_interrupt( serUSART_PORT, US_IER_TXRDY );
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233 /*-----------------------------------------------------------*/
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235 void vSerialClose( xComPortHandle xPort )
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237 /* Not supported as not required by the demo application. */
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240 /*-----------------------------------------------------------*/
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243 * It should be noted that the com test tasks (which use make use of this file)
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244 * are included to demonstrate queues being used to communicate between tasks
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245 * and interrupts, and to demonstrate a context switch being performed from
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246 * inside an interrupt service routine. The serial driver used here is *not*
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247 * intended to represent an efficient implementation. Real applications should
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248 * make use of the USARTS peripheral DMA channel (PDC).
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250 void USART1_Handler( void )
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252 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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255 uint32_t ulUSARTStatus, ulUSARTMask;
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257 ulUSARTStatus = usart_get_status( serUSART_PORT );
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258 ulUSARTMask = usart_get_interrupt_mask( serUSART_PORT );
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259 ulUSARTStatus &= ulUSARTMask;
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261 if( ( ulUSARTStatus & US_CSR_TXRDY ) != 0UL )
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263 /* The interrupt was caused by the TX register becoming empty. Are
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264 there any more characters to transmit? */
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265 if( xQueueReceiveFromISR( xCharsForTx, &ucChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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267 /* A character was retrieved from the queue so can be sent to the
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269 usart_putchar( serUSART_PORT, ( uint32_t ) ucChar );
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273 usart_disable_interrupt( serUSART_PORT, US_IER_TXRDY );
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277 if( ( ulUSARTStatus & US_CSR_RXRDY ) != 0UL )
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279 /* A character has been received on the USART, send it to the Rx
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281 usart_getchar( serUSART_PORT, &ulChar );
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282 ucChar = ( uint8_t ) ( ulChar & 0xffUL );
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283 xQueueSendFromISR( xRxedChars, &ucChar, &xHigherPriorityTaskWoken );
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286 /* If sending or receiving from a queue has caused a task to unblock, and
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287 the unblocked task has a priority equal to or higher than the currently
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288 running task (the task this ISR interrupted), then xHigherPriorityTaskWoken
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289 will have automatically been set to pdTRUE within the queue send or receive
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290 function. portEND_SWITCHING_ISR() will then ensure that this ISR returns
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291 directly to the higher priority unblocked task. */
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292 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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