bitwise Operators

[Sean Shao]

Due to the fact that the bitwise operators in RunRev do not work on signed 
integers, nor do they have shiftLeft and shiftRight, I decided to write my 
own, so here they are.. I'll put them on my website another day.. As always, 
these are released into the Public Domain.. Any questions, comments, 
suggestions feel free to email me..

All parameters are signed integers (ie. 200, -9, 32)

function bitwiseAnd p1, p2     -- in other languages  ( 9 & 2 )
  local tP1Neg, tP2Neg
  if (p1 < 0) then
    put bitNot abs(p1) +1 into p1
    put TRUE into tP1Neg
  end if
  if (p2 < 0) then
    put bitNot abs(p2) +1 into p2
    put TRUE into tP2Neg
  end if
  if (tP1Neg) AND (tP2Neg) then
    return 0 - bitNot ((p1 bitAnd p2) -1)
  else return p1 bitAnd p2
end bitwiseAnd

function bitwiseOr p1, p2     -- in other languages ( 9 | 2 )
  local tP1Neg, tP2Neg
  if (p1 < 0) then
    put bitNot abs(p1) +1 into p1
    put TRUE into tP1Neg
  end if
  if (p2 < 0) then
    put bitNot abs(p2) +1 into p2
    put TRUE into tP2Neg
  end if
  if (tP1Neg) OR (tP2Neg) then
    return 0 - bitNot ((p1 bitOr p2) -1)
  else return p1 bitOr p2
end bitwiseOr

function bitwiseXor p1, p2     -- in other languages ( 9 ^ 2 )
  local tP1Neg, tP2Neg
  if (p1 < 0) then
    put bitNot abs(p1) +1 into p1
    put TRUE into tP1Neg
  end if
  if (p2 < 0) then
    put bitNot abs(p2) +1 into p2
    put TRUE into tP2Neg
  end if
  if (tP1Neg) AND (tP2Neg) then
    return p1 bitXor p2
  else if (tP1Neg) OR (tP2Neg) then
    return 0 - bitNot ((p1 bitXor p2) -1)
  else return p1 bitXor p2
end bitwiseXor

function bitwiseNot p1     -- in other languages ( ~9 )
  return 0 - (p1 + 1)
end bitwiseNot


### parameter p2 is the amount to shift over

function bitwiseShiftLeft p1, p2     -- in other languages ( 9 << 2)
  return p1 * (2 ^ p2)
end bitwiseShiftLeft

function bitwiseShiftRight p1, p2     -- in other languages ( 9 >> 2 )
  if (p2 > 0) then return trunc(p1 / (2 ^ p2))
  if (p2 = 0) then return p1
  if (p1 < 0) then return trunc(p1 / (2 ^ p2)) -1
end bitwiseShiftRight

function bitwiseShiftRightZero p1, p2     -- in other languages ( 9 >>> 2 )
  if (p1 > 0) then return trunc(p1 / (2 ^ p2))
  if (p2 = 0) then return p1
  if (p1 < 0) then
    put baseConvert(bitNot abs(p1) +1, 10, 2) into p1
    repeat p2
      delete char -1 of p1
      put 0 before p1
    end repeat
    return baseConvert(p1, 2, 10)
  end if
end bitwiseShiftRightZero

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