os_measurecst_hrtimer_printf.c

An Demo of uCGUI from SEGGER

/*********************************************************************
*               SEGGER MICROCONTROLLER SYSTEME GmbH                  *
*       Solutions for real time microcontroller applications         *
**********************************************************************
*                                                                    *
*       (c) 1995 - 2007  SEGGER Microcontroller Systeme GmbH         *
*                                                                    *
*       www.segger.com     Support: [e-mail]               *
*                                                                    *
**********************************************************************
*                                                                    *
*       embOS * Real time operating system for microcontrollers      *
*                                                                    *
*                                                                    *
*       Please note:                                                 *
*                                                                    *
*       Knowledge of this file may under no circumstances            *
*       be used to write a similar product or a real-time            *
*       operating system for in-house use.                           *
*                                                                    *
*       Thank you for your fairness !                                *
*                                                                    *
**********************************************************************
*                                                                    *
*       embOS version: 3.32p                                         *
*                                                                    *
**********************************************************************

----------------------------------------------------------------------
File    : OS_MeasureCST_HRTimer_Printf.c
Purpose : Performance test program for OS
          This benchmark measures the context switch time and displays 
          the result on CSpy's terminal I/O window. It runs with every
          IAR workbench that supports terminal I/O with printf.
--------  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) {
  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
    printf("Context switch time: %u.%.3u usec\r\n", v / 1000, v % 1000);     // Print out result
  }
}