BITSET sets the value of a specified bit in the bit table to one and returns the value of the bit before it was changed. It takes the general form:
table_no specifies the bit to be SET. If table_no evaluates to zero, it sets all elements in the table to one and the returned value is one.
For each purpose, BITSET 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.
BITSET returns the previous value of the bit - you can check and set a flag in one step.
BITSET also provides some special functions if you use one of the following table_no values:
- -1 sets the BREAK key Inhibit bit
- -2 sets the Command Level Restart feature
- -3 sets the Break/End Restart feature
An example of use is as:
OLD.VALUE = BITSET (112) PRINT OLD.VALUE
If table entry 112 is zero, returns a value of zero, sets bit 112 to one, and prints zero. If table entry 112 is one, returns a value of one, and prints one.
See also: BITRESET.
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