If Then Array Oddity

[atillotson]

I have a small piece of code That acts very unusual, I got from Bruce, I Believe. Anyway if you look at the label "ThisDoesnt" and compare it to the Label "ThisWorks" you may be able to spot the problem. However, I cant find any reason why this shouldnn't work. But it will not work for me.
I'm using PBP 2.46 and a lovely 18f2620.


DEFINE OSC 4
DEFINE HSER_BAUD 19200
DEFINE HSER_CLROERR 1 ' Automatically clear over-run errors
DEFINE HSER_RCSTA 90h ' Enable USART receive
DEFINE HSER_TXSTA 24h ' TXSTA=%00100100. TX enable, BRGH=1 for high-speed

GP VAR BYTE ' GP variable
BytesIn var byte[5] ' 0 thru 4 bytes
ByteCnt var byte ' Indicates number of bytes in buffer

OERR VAR RCSTA.1 ' Alias USART over-run bit
CREN VAR RCSTA.4 ' Alias USART continuous receive enable bit
RCIF VAR PIR1.5 ' Alias USART received character interrupt flag bit
INTCON = 0 ' Disable interrupts
ByteCnt = 0 ' Zero counter
ADCON1 = 7 ' A/D off, all digital
OSCCON=%01100000 ' Set internal osc to 4MHZ

Main:
IF oerr then
cren=0
cren=1
endif
IF RCIF THEN ' If RCIF=1 there's a new character in RCREG
BytesIn[ByteCnt]=RCREG ' Yes. Then store it in array
IF ByteCnt = 4 THEN ThisWorks ' IF BytesIn[ByteCnt]=EOM THEN OutMsg
ByteCnt=ByteCnt+1 ' Increment array index pointer
ENDIF
GOTO Main

ThisWorks:

if bytesin[0]= $80 then Weird
Weird:
HSEROUT ["up",str BytesIn\ByteCnt ,13,10]
FOR GP=0 TO ByteCnt ' Clear array bytes 0 to ByteCnt
BytesIn[GP]=0 '
NEXT gp '
ByteCnt=0 ' Reset index pointer back to first element
WHILE RCIF ' Keep reading until RCIF is clear to flush buffer
GP=RCREG ' after EOM is received
WEND
GOTO Main

ThisDoesnt:

if bytesin[0]= $80 then

HSEROUT ["up",str BytesIn\ByteCnt ,13,10]
endif

FOR GP=0 TO ByteCnt ' Clear array bytes 0 to ByteCnt
BytesIn[GP]=0 '
NEXT gp '
ByteCnt=0 ' Reset index pointer back to first element
WHILE RCIF ' Keep reading until RCIF is clear to flush buffer
GP=RCREG ' after EOM is received
WEND
GOTO Main

Also I have replaced this line (if bytesin[0]= $80 then) with a "> 7F and <81" and it works fine. But as soon as I use the "=" to i get nothing.
Could some someone please explain this to me?

thanks ash

[Bruce]

This will work no matter what bytesin[0] is.

ThisWorks:

if bytesin[0]= $80 then Weird
Weird: '<--- fall through to here regardless
HSEROUT ["up",str BytesIn\ByteCnt ,13,10]

Change it to something like;

if bytesin[0]= $80 then Weird
Goto SomeWhereElse ' Jump over weird if bytesin[0] not = $80

Weird:
HSEROUT ["up",str BytesIn\ByteCnt ,13,10]

[atillotson]

Thanks Bruce, But what i need to understand is why this statement below doesn't produce a result.
________________________________________
if bytesin[0]= $80 then
HSEROUT ["up",str BytesIn\ByteCnt ,13,10]
endif
________________________________________

I can use (if bytesin[0]> $7f then) and (if bytesin[0]< $81 then)
in any combination of nested (IF THEN) statements and it works as long as i dont ask it to "=". See code Below, This it what i need to work but doesn't.
If I send the same code from my serial display to my PC I can see that bytesin[0] is infact = to $80.
I also got this code to work using a select case statement.
Basically what im saying is my IF THEN doesn't like "=" if using an array for comparison. But will Compare if using Greater than or less than.
I KNOW, its not logical, thats why i really need your help.

thanks ash

DEFINE OSC 4
DEFINE HSER_BAUD 19200
DEFINE HSER_CLROERR 1 ' Automatically clear over-run errors
DEFINE HSER_RCSTA 90h ' Enable USART receive
DEFINE HSER_TXSTA 24h ' TXSTA=%00100100. TX enable, BRGH=1 for high-speed

GP VAR BYTE BytesIn var byte[5]
ByteCnt var byte
OERR VAR RCSTA.1
CREN VAR RCSTA.4 RCIF VAR PIR1.5 INTCON = 0
ByteCnt = 0
ADCON1 = 7 '
OSCCON=%01100000

Main:
IF oerr then
cren=0
cren=1
endif
IF RCIF THEN
BytesIn[ByteCnt]=RCREG
IF ByteCnt = 4 THEN MsgOut
ByteCnt=ByteCnt+1
ENDIF
GOTO Main

MsgOut:

if bytesin[0]= $80 then
HSEROUT ["up",str BytesIn\ByteCnt ,13,10]
endif

FOR GP=0 TO ByteCnt
BytesIn[GP]=0
NEXT gp
ByteCnt=0
WHILE RCIF
GP=RCREG
WEND
GOTO Main

[Bruce]

My guess would be it never = $80. Standard ASCII is from $00 to $7F. Extended ASCII starts at $80.

[atillotson]

That was what i thought as well, However I have used 3 different Communication capture programs and am able to determine that it is infact $80 Even PBP will say its $80 as long as I use a different way to compare than the one shown. again if its > $7f and < $81 - it will work. Or i can use select case and that works fine as well
But it doesn't work if I compare with the = sign with an array in my If Then condition.
ash

[Bruce]

And what happens if you do something like this?

Main:
    hserin 5000,Waiting,[hex serdata[0],hex serdata[1]]
    IF serdata[0] = $80 then
     hserout ["Got ",ihex serdata[0]," ",ihex serdata[1],13,10]
    ENDIF
    goto Main   
    
Waiting:
    hserout ["Waiting",13,10]
    Goto Main