detect overflow of multiply/ div32 result

[pedja089]

You can using */ or **.
** will return byte 2 and byte 3 of result, ignoring byte 0 and byte 1.
So you can do something like this:

Dummy = a ** b
If dummy=0 then
    dummy = a*b
    result = div32 100
    multiplicator=1
else
    dummy = a * b
    result = div32 1000
    multiplicator=10
endif

[richard]

perfect thanks for that

[pedja089]

I don't know maximum value of that variables, but if it is $FFFF then maximum number is $FFFE0001, or 4,294,836,225.
So maybe you need to divide with more 10000,100000 etc.
Just use select case or ELSEIF to determine with what value you need to divide.

[richard]

I did this , not tested yet

 
         mult=1
          ;remaining time in seconds =  (left * LAPSE )/100 
          
         REMTIMEHOU = left ** lapse 
         while  REMTIMEHOU 
         mult=mult*10
         
         if lapse >  left  then 
             REMTIMESEC = lapse /mult
             REMTIMEMIN = left
         else    
             REMTIMESEC = left/mult
             REMTIMEMIN = lapse
         endif
         REMTIMEHOU = REMTIMESEC ** REMTIMEMIN
         wend
        select case mult 
        case 1
            REMTIMEHOU = left * lapse 
            REMTIMESEC = div32 100
            REMTIMEHOU=REMTIMESEC//3600
            REMTIMESEC=REMTIMESEC/3600
        case 10
            REMTIMEHOU = left * lapse 
            REMTIMESEC = div32 1000
            REMTIMEHOU=REMTIMESEC//360
            REMTIMESEC=REMTIMESEC/360
        case 100
            REMTIMEHOU = left * lapse 
            REMTIMESEC = div32 10000
            REMTIMEHOU=REMTIMESEC//36
            REMTIMESEC=REMTIMESEC/36
        case else
            ; wtf  error
            
        end select
        
          
          
          
          
          
          REMTIMEMIN=REMTIMESEC//60
          REMTIMESEC=REMTIMESEC/60
          
          
          ARRAYWRITE buff,["REMAINING ",DEC2 REMTIMEHOU,":",DEC2 REMTIMEMIN,":",DEC2 REMTIMESEC,0] 
          GLCDSTR 25,80 ,buff

[pedja089]

I just noticed, that you can easily overflow variable mult after just 5 iteration.
You can just store number of 0 in that variable, or something...

[richard]

was hoping 3 iterations will be enough, but your right

one day I'm going to write a python pbp calculator with
pbp math functions including ** , */ and div32
using unsigned bytes and words

trial and error is tedious and I hate surprise results

[pedja089]

It's not complicated...
C=A*/B is same as C=(A*B)/$FF
C=A**B same as C=(A*B)/$FFFF