Boolean (bitwise) operators

Description

Actually, JB logical operators are bit-wise operators:

AND, OR and XOR

It looks like they operate on 32-bit integers.

There is no bit-wise NOT, but you can compute it as

x XOR -1

(-1 has all 32 bits set to 1, see results of BitPattern$ under Useful Procedures)

Syntax

1. Place all possible forms of the keyword here

Hints

Using logical operators on floating-point numbers makes no sense.

Sometimes, it will fail with a "IsEmpty not understood" error.

(Do NOT expect JB to convert numbers to integers for you in this case.)

Using logical operators on big negative numbers sometimes will fail with a "IsEmpty not understood" error too.

It looks like operator precedence not implemented - use parentheses instead.

Example

print "Example of bitwise operations usage"
print "we will work with 8 bit, for simplicity."
print "You can sure use up to 32 bit in JB."
print

print "Let's start from 0"
a=0
print tab(5);eightBitPattern$(a)
print

print "To set some bits, we use OR"
op = a
op1$ = "1010"
op1 = bin2num(op1$)
print tab(5);eightBitPattern$(op)
print " OR ";eightBitPattern$(op1)
print tab(5);"--------"
res = op or op1
print tab(5);eightBitPattern$(res)
print

print "Now, add some more bits"
op = res
op1$ = "11"
op1 = bin2num(op1$)
print tab(5);eightBitPattern$(op)
print " OR ";eightBitPattern$(op1)
print tab(5);"--------"
res = op or op1
print tab(5);eightBitPattern$(res)
print "note last bit got set, but one just before doesn't change (stays set)"
print

print "To mask (reset) some bits, we use AND"
print "second operator commonly called a mask"
print "bits where mask has 0 will get reset (masked)"
op = res
mask$="11111001"
op1 = bin2num(mask$)
print tab(5);eightBitPattern$(op)
print "AND ";eightBitPattern$(op1); "<< the mask"
print tab(5);"--------"
res = op and op1
print tab(5);eightBitPattern$(res)
print

print "To toggle some bits, we use XOR"
print "let's toggle first and last bit"
op = res
toggeMask$="10000001"
op1 = bin2num(toggeMask$)
print tab(5);eightBitPattern$(op)
print "XOR ";eightBitPattern$(op1)
print tab(5);"--------"
res = op xor op1
print tab(5);eightBitPattern$(res)
print
print "Second XOR with same number restores original"
op = res
print tab(5);eightBitPattern$(op)
print "XOR ";eightBitPattern$(op1)
print tab(5);"--------"
res = op xor op1
print tab(5);eightBitPattern$(res)
print

print "Last, XOR with all the ones works as bitwise NOT"
op = res
toggeMask$="11111111"
op1 = bin2num(toggeMask$)
print tab(5);eightBitPattern$(op)
print "XOR ";eightBitPattern$(op1)
print tab(5);"--------"
res = op xor op1
print tab(5);eightBitPattern$(res)
print

end

'---------------------------------------------
function bin2num(bin$)
    bin2num = 0
    for i = 1 to len(bin$)
        c$=mid$(bin$, i, 1)
        if instr("01",c$)=0 then exit function  'like VAL(), break on first non-valid digit
        bin2num = bin2num*2+(instr("01",c$)-1)
    next
end function

function eightBitPattern$(num)
    for i = 0 to 7
        eightBitPattern$ = str$((num and 2 ^ i) > 0) + eightBitPattern$
    next i
end function

Useful Procedures

function BitPattern$(num)
    for i = 0 to 31
        if i mod 8 = 0 then BitPattern$ = " " + BitPattern$
        BitPattern$ = str$((num and 2 ^ i) > 0) + BitPattern$
    next i
end function

function bitwiseNot(num)
     bitwiseNot = num XOR -1
end function