SetBit

Description:              This function sets or clears a specific bit in a value and returns the result.

Returns:                    Numeric

Usage:                   Script or Steady State

Format:                      SetBit(Value, BitNumber, Option)

Parameters:             Value    { numeric }  { required }  { no default: }

                                                Any numeric expression that gives the number to modify the bit in.

                                    BitNumber    { numeric }  { required }  { no default: }

                                                Any numeric expression giving the bit number to set or clear. Bit 0 is the least significant bit. Legal values are from 0 to 31 inclusive.

                                    Option   { Boolean }  { required }  { no default: }

                                                Any status expression indicating whether the bit is to be set or cleared in the Value. A true indicates that the bit is to be set (i.e. set to 1), and a false indicates that it is to be cleared (i.e. set to 0).

Comments:               This function is useful for saving a series of status values in a single short or long variable. If any argument is invalid, the return value is invalid.

Examples:

a = SetBit(0, 1, 1);

In this simple example, the values for a will be 2 { 0b00000010 }. This is not a particularly useful example of SetBit, though. Most likely you will want to use it in a statement like the following:

b = SetBit(b, 2, 1);

In this case, bit number 2 will be set to 1. It is important to note, however, that if b is invalid, this statement will have no effect (i.e. it will not make b valid). A safer way to accomplish the setting of bit 2, then, might be to write

b = SetBit(PickValid(b, 0), 2, 1);

so that the b being invalid case is covered.

See Also:

Bit