AMX 68000, Target Guide - page 55

AMX 68000 Target Guide
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Device I/O Delay
The Target Parameter File includes a device I/O delay definition.
...DELAY CPUFREQ
CPUFREQ M68000 processor instruction execution frequency (MHz)
The ...DELAY directive allows you to condition the delay loop of the AMX device I/O
delay procedure cjcfhwdelay to match your hardware requirements. This directive
allows AMX to use your estimate of the processor's instruction execution frequency
defined by parameter CPUFREQ to derive the loop count needed to provide a one
microsecond delay.
Null Function Declarations
To create a null function, a function that does nothing, include the following directive in
your Target Parameter File.
...NULLFN FNNAME
FNNAME Name given to the null function
For every ...NULLFN directive, your Target Configuration Module will include a public
assembly language function with name given by your parameter FNNAME. The function
will do nothing but return to the caller.