jBase Command BITCHANGE

BITCHANGE toggles the state of a specified bit in the local bit table, and returns the original value of the bit.

Command Syntax

BITCHANGE (table_no)

Syntax Element

table_no specifies the position in the table of the bit to be changed.

Notes

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.

Example

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.