IB Statements/setbit

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SETBIT function

Discussion: The SETBIT function sets the specified bit in a string expression.

Syntax: Result = SETBIT(string-expression, bit-location, bit-value [,EXCP=label])

Where: Result contains the value of the bit before it was set. Valid values are 0 and 1.

String-expression is a string value encoded in binary form.

Bit-location is a numeric value specifying the bit that is to be set.

Bits are 0-based and are ordered according to the following scheme:

If the string-expression contains 8 bits, they are ordered:

7 6 5 4 3 2 1 0

If the string-expression contains 16 bits, they are ordered:

7 6 5 4 3 2 1 0 15 14 13 12 11 10 9 8

If the string-expression contains 24 bits, they are ordered:

7 6 5 4 3 2 1 0 15 14 13 12 11 10 9 8 23 22 21 20 19 18 17 16

Bit-value is 0 or 1.

An exception occurs if the program attempts to set a bit beyond the declared length of the string-expression.

Example:

 A$ = “@0000@”
!
 B$ = HEXASC(A$)
 Print “Before:”;B$
 !
 FOR I = 8 TO 11
 J = SETBIT(A$,I,1,EXCP=9999)
 Print “Bit”;I;”was”;J
 NEXT I
 !
 B$ = HEXASC(A$)
 Print “After”;B$