macro isNot()

[Chris Roper]

These commands are now included in the general distribution of GCB @ September 2015

GCBasic lacks the ability to compliment a BIT therfor operations such as:

PortB.3 = NOT PortB.3

fail with an obscure warning but comple producing bad code.

This macro is a work around which I hope will be of use to others:

Macro isNot(BitOut, BitIn)
  If BitIn then
     BitOut = 0
  Else
     BitOut = 1
  End If
End Macro

BitIn is the BIT to be Complimented
BitOut is the BIT to SET/CLEAR
BitIn and BitOut may be the same

Examples:

' Flash an LED
'#define LED PortB.3

Do
  isNot(LED, LED)  ' LED != LED
  wait 500 ms
Loop

' toggle LED according to a Button
'#define LED PortB.3
'#define PB1 PortE.3

Do
  isNot(LED, PB1)  'LED = NOT PB1
Loop

It will work on any bit field so

Dim Flag as bit
isNot(Flag, Flag)

is valid as it

dim test as byte

isNot(Flag, test.1 )
LED = Flag

Cheers
Chris

[Chris Roper]

I added two additional Bitwise Operators that are sadly missing and present it here as a macro Library and an example program:

' Bitwise Macros.h

' BitOut != BitIn
Macro isNot(BitOut, BitIn)
  If BitIn then
     BitOut = 0
  Else
     BitOut = 1
  End If
End Macro

' BitsOut = BitsIn << NumBits
Macro LSL(BitsOut, BitsIn, NumBits)
  BitsOut = BitsIn
  Repeat NumBits
    STATUS.C = 0
    Rotate BitsOut Left
  End Repeat
End Macro

' BitsOut = BitsIn >> NumBits
Macro LSR(BitsOut, BitsIn, NumBits)
  BitsOut = BitsIn
  Repeat NumBits
    STATUS.C = 0
    Rotate BitsOut Right
  End Repeat
End Macro

Example Program for 28 Pin Demo Board - Reversable Chase lights

#Chip     18f25k50            ' Target Device Name
#Config   MCLR = Off

#include "Bitwise Macros.h"

Setup:

Dir PortB Out

Mainloop:
Do

  wait 500 ms

  if Direction then
      LSL(PortB, PortB, 1)  ' PortB = PortB << 1
      if PortB.4 then
         PortB = 1
      end if
  else
      LSR(PortB, PortB, 1)  ' PortB = PortB >> 1
      if PortB = 0 then
         PortB.3 = 1
      end if
  end if

  isNot(SW1, PortE.3)      ' SW1 = NOT PortE.3
  if SW1 then Direction = NOT Direction

Loop

Subs:

Exit:
END

I Hope it is useful
Cheers
Chris

[Chris Roper]

Forgive all the edits, I couldn't get the code highlighting and formating to work but slowly it is getting there,

[Anobium]

Thank you Chris.

With your agreement I would like to move these into the general distrubtion of Great Cow Basic.

I will move into stdbasic.h which means that you do not need the include file for these three methods.

Anobium

[Chris Roper]

By all means, I would be honoured to have made a contribution towards all your great work.
Cheers
Chris