The BBC and Master Computer Public Domain Library

ACB7 ABS

Submitted by Steve Fewell

Description:

Call the Evaluate value routine (&AD36) which will evaluate the next value at BASIC text
pointer B location, or the expression at that location if the value begins with an open bracket ("(").
If the returned value is a String (A = 0) then issue a Type mismatch error as the value is not numeric.

If the returned value is a Floating-Point value then jump to &ACC4 to set the FWA Sign byte to zero.
This will force the FWA's sign to be positive.
Otherwise, continue to the Integer Positive routine (&ACBE), which will make the number in the IWA positive.

Disassembly for the ABS routine