os_measurecst_hrtimer_embosview.c

An Demo of uCGUI from SEGGER

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*               SEGGER MICROCONTROLLER SYSTEME GmbH                  *
*       Solutions for real time microcontroller applications         *
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*       embOS * Real time operating system for microcontrollers      *
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*       Please note:                                                 *
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*       embOS version: 3.32p                                         *
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----------------------------------------------------------------------
File    : OS_MeasureCST_HRTimer_embOSView.c
Purpose : Performance test program for OS
          This benchmark measures the OS context switch time and
          displays the result in the terminal window of embOSView.
          It is completly generic and runs on every target that is
          configured for embOSView.
--------  END-OF-HEADER  ---------------------------------------------
*/

#include "RTOS.h"
#include "stdio.h"

static OS_STACKPTR int StackHP[128];                // Task stacks
static OS_TASK TCBHP;                               // Task-control-blocks
static OS_U32 _Time;                                // Timer value for context switch measurement

/*********************************************************************
*
*       HPTask
*/
static void HPTask(void) {
  while (1) {
    OS_Suspend(NULL);                   // Suspend high priority task 
    OS_Timing_End(&_Time);              // Stop measurement
  }  
}

/*********************************************************************
*
*       MainTask
*/
void MainTask(void);
void MainTask(void) {
  char   acBuffer[100];                 // Output buffer
  OS_U32 MeasureOverhead;               // Time for Measure Overhead
  OS_U32 v;                             // Real context switch time
  
  OS_CREATETASK(&TCBHP, "HP Task", HPTask, 150, StackHP);
  OS_Delay(1);
  //
  // Measure Overhead for time measurement so we can take this into account by subtracting it
  //
  OS_Timing_Start(&MeasureOverhead);
  OS_Timing_End(&MeasureOverhead);
  //
  // Perform measurements in endless loop
  //
  while (1) {
    OS_Delay(100);                    // Syncronize to tick to avoid jitter
    OS_Timing_Start(&_Time);          // Start measurement
    OS_Resume(&TCBHP);                // Resume high priority task to force task switch
    v = OS_Timing_GetCycles(&_Time) - OS_Timing_GetCycles(&MeasureOverhead);      // Calculate real context switch time (w/o measurement overhead)
    v = OS_ConvertCycles2us(1000 * v);                                            // Convert cycles to nano-seconds, increase time resolution
    sprintf(acBuffer, "Context switch time: %u.%.3u usec\r", v / 1000, v % 1000); // Create result text
    OS_SendString(acBuffer);                                                      // Print out result
  }
}