I made the suggested changes to the code. I have tried dividing
different numbers and get strange results. Here is what I am seeing.

For:
        MOVLW   0x01
        MOVWF   DIVIDENDHI=20
        MOVLW   0xF4
        MOVWF   DIVIDENDLO
        MOVLW   0x00
        MOVWF DIVISORHI=20
        MOVLW   0x02
        MOVWF DIVISORLO
        I get 0xE8E8

And with

        MOVLW   0x03
        MOVWF   DIVIDENDHI=20
        MOVLW   0xE8
        MOVWF   DIVIDENDLO
        MOVLW   0x00
        MOVWF DIVISORHI=20
        MOVLW   0x02
        MOVWF DIVISORLO
        I get 0x0758

And if I divide 16/2 I get 8, sometimes.=20
TX_V    BANK0

        MOVLW   0x00
        MOVWF   DIVIDENDHI=20
        MOVLW   0x10
        MOVWF   DIVIDENDLO
        MOVLW   0x00
        MOVWF   DIVISORHI=20
        MOVLW   0x02
        MOVWF   DIVISORLO
        PCALL   DIVIDE16
        MOVF    QUOTIENTLO,W
        PCALL   transmitw
        MOVF    QUOTIENTHI,W
        PCALL   transmitw
        GOTO    RX_CMD_FINISH

It cycles through a couple of answers each time it is called.=20
It will give 4096, 22561, and 8=20


Any ideas

Charles K Roberts II


-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Andrew Warren
Sent: Wednesday, November 19, 2003 2:58 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC]: 16 bit by 16 bit unsigned divide with PIC 17F873A

I just wrote (although I should really know better):

> Since the code is known to work (I wouldn't have put it on my web page
> if it didn't), the problem must be elsewhere.

Just noticed an error in the code posted to my web page:  There's an
"INCFSZ DIVISORHI" near the end of it; that line should read "INCFSZ
DIVISORHI,W".

Even WITH the error, though, the code produces the correct result
when given the particular inputs you were using (dividend =3D 0x0808,
divisor =3D 0x0404), so I still suspect that there's a radix issue in
your implementation.

-Andy

=3D=3D=3D Andrew Warren -- aiw@cypress.com
=3D=3D=3D Principal Design Engineer
=3D=3D=3D Cypress Semiconductor Corporation
=3D=3D=3D
=3D=3D=3D Opinions expressed above do not
=3D=3D=3D necessarily represent those of
=3D=3D=3D Cypress Semiconductor Corporation

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