Calculator Programming Tutorial

Programming Building Blocks I

Examples

Logical Operations for the Calculator

Program Code

Given all the previous analysis, the FX-7400G program absolutely flows into the calculator.

Program BOOLOP (51 bytes):

; Performs a boolean operation upon two boolean values. Any boolean
; valued function of two boolean arguments may be specified
;
; The boolean arguments are placed into A and B. These are regarded as
; true and false as they are non-zero or zero, respetively. The code
; for the function to be performed is placed into C. The function code
; is constructed from the truth table for the desired function as
; follows:
;
;     A  B  c
;     0  0  1
;     0  1  2
;     1  0  4
;     1  1  8
;
; The function code is the sum of the c values corresponding to true
; entries in the truth table.
;
; (Popular functions: 3 is not A, 5 is not B, 14 is A or B, 6 is
; A xor B, 8 is A and B.)
;
; Variables:
;   A is the first boolean value; this value is retained
;   B is the second boolean value; this value is retained
;   C on entry is the function code as described above; on exit is the
;     specified boolean function of A and B
;   Ans is on exit the specified boolean function of A and B
;
; Symbols:
;   <> is the not equal relational
;   => is the conditional operator
;   / is the division operator
;   -> is the assignment arrow
 
A<>0=>C/4->C       ; If A, then right shift function code 2 bits
B<>0=>C/2->C       ; If B, then right shift function code 1 bit
2Frac ((Int C)/2)->C
                   ; Extract result into C
C                  ; Return result in Ans as well

And there we have it, all 16 logical operations in four statements, in a subprogram taking 51 bytes! We call the program BOOLOP, for BOOLean OPeration, and we are done.

Well, almost done. We still have the unit test to do.

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