Tony Walduck
While writing a menu-based utility (the violin scales and
arpeggios program also featured in this issue) I wished to make it possible to
easily repeat a menu selection after it had been acted upon. These notes
describe the solution I developed.
I decided to allow the automatic reselection of a previous
menu choice by putting a repeat option as the first menu line.
All other menu lines write a number into a GVAR variable as
well as actioning their intended response. The number written is the number of down-key
presses needed to position the highlight on that menu line.
The repeat menu option reads the GVAR variable, flushes the
keyboard input buffer (*FX15,1) and, if the variable is not zero (which would
cause it to loop), inserts that number of down-key codes into the input buffer
(*FX138), followed by a Return code to re-select the previous menu line.
The program U.VSA (Violin scales and arpeggios - accessible
from this Utilities menu) contains a much-modified version of this technique.
In this one program, nearly 80 music pieces can be chosen and easily repeated.
The reason the technique has been modified is that, as I
rapidly came to the 125 user-word limit as well as space limitations, I had to
employ whatever constructions would allow me to economise on both. Consequently
the program structure is less clear than I would have liked it to be.
Related files on this disc:
Published in AMPLINEX 027, July 1992
