BITCHANGE toggles the state of a specified bit in the local bit table, and returns the original value of the bit. It takes the general from:
table_no specifies the position in the table of the bit to be changed.
For each process, it maintains a unique table of 128 bits (numbered 1 to 128) and treats each bit in the table as a two-state flag - the value returned will always be zero or one.
BITCHANGE returns the value of the bit before it was changed. You can therefore check and set (or reset) a flag in one step.
BITCHANGE also provides some special functions if you use one of the following table_no values:
- -1 toggles (enables/disables) the BREAK key Inhibit bit.
- -2 toggles (enables/disables) the Command Level Restart feature.
- -3 toggles (enables/disables) the Break/End Restart feature.
An example of use is as:
OLD.VAL = BITCHANGE (100) CRT OLD.VAL
If bit 100 in the table is zero, it sets to one and displays zero; the reverse will apply if set to one..
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