'****************************************************************
'*  Name    : MATH32u.BAS                                       *
'*  Author  : Ranjit Diol    http://www.compsys1.com/workbench/ *
'*  Notice  : Copyright (c) 2003 COMPSys                        *
'*          : All Rights Reserved                               *
'*  Date    : 9/18/03                                           *
'*  Version : 1.0                                               *
'*  Notes   :  32 bit Add/Subbtract Routines                    *                             
'*          :  Use a terminal for the demonstration             *
'*          :  9600 baud 8,N,1                                  *
'*          :  Compiler: PICBasicPro Ver 2.43                   *
'*                                                              *
'****************************************************************
'
'****************************************************************
'   DISCLAIMER: This file is being released as non-commericial  *
'   software. It is being provided "AS IS", neither the author, * 
'   nor COMPSys shall be held liable for any damages, direct or *
'   indirect caused by its use.                                 *
'****************************************************************
'
'Notes:
' Since PBP does not have a double word type 32 bit values have to be made up
' of two word variables. Hexadecimal values are used to load the variables
' 32bit value = HIGH word and LOW  word
' Num32 = Num1H and Num1L , where Num1H and Num1L are 16bit word values
'
'Example:                      
' Num1 = 2234567890 decimal =  8530 CCD2 hexadecimal
' Num2 = 1098765432 decimal =  417D D478 hexadecimal
' Addition:
' Num1 + Num2 = 3333333322 decimal = C6AE A14A  hexadecimal
' Subtraction:
' Num1 - Num2 = 1135802458 decimal = 43B2 F85A  hexadecimal
'
' Results are returned in Res32H and Res32L
'
'Note: All values are unsigned
'
'****************************************************************
'  Variables:
'                Num1H,Num1L is the pair for the first 32bit number
'                Num2H,Num2L is the pair for the second 32bit number 
'                Res32H, Res32L is the pair for the result
'                cbit is a bit variable which is used to hold the carry result
'
'MCU: PIC16F877 w/20Mhz osc and a Max232 for serial I/O
DEFINE LOADER_USED 1         'If using a bootloader
DEFINE OSC 20                'Xtal speed
DEFINE DEBUG_REG PORTC       'Debug pin port 
DEFINE DEBUG_BIT 6           'Debug pin bit 
DEFINE DEBUG_BAUD 9600       'Debug baud rate 

'MODE: TRUE (if using a MAX232) or INVERTED (direct connection)
DEFINE DEBUG_MODE 0          'Debug mode: 0 = True, 1 = Inverted 
DEFINE DEBUGIN_MODE 0        'Debugin mode: 0 = True, 1 = Inverted 

DEFINE DEBUGIN_REG PORTC     'Debugin pin port 
DEFINE DEBUGIN_BIT 7         'Debugin pin bit 


SYMBOL cb=STATUS.0           'Carry status register  bit

Res32H var word              'Result high word
Res32L var word              'Result low word
Num1H  var word              'Number 1  high word
Num1L  var word              'Number 1  low word
Num2H  var word              'Number 2  high word
Num2L  var word              'Number 2  low word 
cbit   var bit               'Carry bit


debug 13,10,"Starting..",13,10

goto Demo

'*********** SUB ROUTINES ***************
'32 bit Addition unsigned
'Given Num1H,Num1L,Num2H,Num2L  returns Res32H,Res32L
Add32unsigned: 
	Res32L = Num1L + Num2L     'Add the low values
    cbit = cb                  'Check the carry bit
    Res32H=Num1H+Num2H+cbit    'Add the high values plus the carry bit
return

'32 bit Subtraction unsigned
Sub32unsigned:
	Res32L = Num1L - Num2L     'Subtract the low values
    cbit = cb                  'Check the carry bit
    if cbit = 1 then
       Res32H=Num1H-Num2H      'No carry
    else
       Res32H=Num1H-Num2H-1    'Adjust for the carry bit  
    endif     
return        
'*********** END SUB ROUTINES ************
Demo:
debug 10,13,"DEMO of 32 bit insigned Addition & Subtraction",13,10
debug "32bit values: Num1 = 2234567890 (dec) = 8530CCD2 (hex)",13,10
debug "              Num2 = 1098765432 (dec) = 417DD478 (hex)",13,10
   'Assign the word values in hex
    Num1H = $8530 : Num1L = $CCD2
    Num2H = $417D : Num2L = $D478
'Perform the calculations.
'The results should be: Addition=C6AEA14A  Subtraction=43B2F85A
debug 13,10,"Calculated results:",13,10
goto Calc  

'============ MAIN PROGRAM ===============
Main: 
debug 10,13,"You can try it by entering two 32bit numbers as hex values",13,10
debug "The first number should be the one with the higher value",13,10
debug "Enter a ~ (tilde) to begin.....",13,10

debugin [wait("~")]
 
debug 13,10,"Enter Num1 as a high word and low word in hex",13,10
debugin   20000,Main,[hex4 Num1H,hex4 Num1L]

debug 13,10,"Enter Num2 as a high word and low word in hex",13,10
debugin   20000,Main,[hex4 Num2H,hex4 Num2L]

Calc:
gosub Add32unsigned
debug 13,10,"ADDITION Result in hex: ",hex4 Res32H,Hex4 Res32L, " (Carry bit=",dec cbit,")",10,13

gosub Sub32unsigned
debug 13,10,"SUBTRACTION Result in hex: ",hex4 Res32H,Hex4 Res32L, " (Carry bit=",dec cbit,")",10,13

goto main
'========= END MAIN PROGRAM =============
end