Each test took the basic form demonstrated by the pseudo code below:
Setup hardware;
Loop forever
Set digital output;
Perform operation
Perform operation
.
.
.
Perform operation
Perform operation
Clear digital output;
End loop
The loop is just so the program execution continues ad infinitum, facilitating measurement.
The setting and clearing of the digital output mark the start and end of the measured period respectively. This period was recorded using a 100MHz digital oscilloscope.
The operation under test is executed a number of times inline within the start and end markers. This reduces to insignificance the proportion of time taken to set and clear the output, along with any output rise or fall time. The following pages detail what constitutes an "operation" for each test.
Selected tests were performed both with and without the C compiler optimization.
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