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CHAPTER2 Dependence Functions
2.3.6 Measuring Execution Cycle Count
This function measures the program execution time.
■ The measuring item
Measures program execution time and cycle count.
The resolution of the execution time is 25ns, and up to "(2 to the power of 64 - 1) x 25ns" can be measured.
Also, the maximum number of cycles that can be measured is "2 to the power of 64 - 1", in other words, up
to 18,446,744,073,709,551,615 cycles.
The measurement is performed whenever a program is executed, and the measurement result displays the
following two values:
• Number of cycles spent on the previous program execution
• Total number of cycles executed since the previous clearing
■ Displaying Measurement Results
Either of the following methods can be used to display the measurement results.
1. Display by dialog
The results appear in the time measurement dialog, which can be displayed by selecting [Debug] –
[Time Measurement] menu.
2. Display by command
Enter the SHOW TIMER command in the command window.
■ Clearing Measurement Results
Either of the following methods can be used to clear the measurement results.
1. Operation by dialog
Click the [Clear] button in the time measurement dialog, which can be displayed by selecting [Debug] –
[Time Measurement] menu.
2. Clearing by command
Enter the CLEAR TIMER command in the command window.
■ Error
The number of measurement cycles includes an error of about 20 cycles. In the Real-time mode or Full
Trace mode, it has additionally an error of about at most (*1) cycles. For time measurement, use the
Internal Trace mode or External Trace mode, which has less error.
Note:
Execution cycle counts are measured in several tens of cycles at one execution. When measuring
execution cycles, set for consecutive executions of many instructions to decrease the efficacy of
errors.
Execution time as well as execution cycle are measured in several tens of cycles.
*1: Autowait 1 : +1250
Autowait 3 : +2500
Autowait 7 : +5000
Autowait 15 : +10000