RE: Counting records in a binary file

["Jeff Wise" <jwise@...>]

> - convert bytes 2,3 to a number 'N'
> - skip N bytes

I'm sorry, but I have no clue how to convert bytes 2,3 to a number, nor how to skip N bytes. Can you elaborate, perhaps a code snippet?

In my world, assuming reg 2 points to the first byte:

       SR   R10,R10      Zero count register
LOOP   DS   0H
       CLI  R2,X'5A'     Is first byte 5A?
       BNE  NO5A         No, skip processing
       LA   R10,1(,R10)  Bump count reg by 1  
       LH   R3,1(,R2)    Pick up halfword length
       LA   R2,1(R3,R2)  Accommodate the length field
       B    LOOP         Go to Loop
NO5A   DS   0H
*  Bad data, no '5A' header

I do realize this code doesn't look for the end of the data...


-----Original Message-----
From: lua-bounces@bazar2.conectiva.com.br [mailto:lua-bounces@bazar2.conectiva.com.br] On Behalf Of Javier Guerra
Sent: Monday, September 15, 2008 10:43 AM
To: Lua list
Subject: Re: Counting records in a binary file

On Mon, Sep 15, 2008 at 10:07 AM, Jeff Wise <jwise@sealyrealty.com> wrote:
> ➢ ignore it, and don't waste time trying to use it
>
> I must count the records. Each record begins with '5A'. After this '5A' is a 2 byte length but it does not account for the '5A'. Unfortunately "gsub" will not count the records because there are '5A' embedded.  Here is an example of the form '5A', nnnn, data bytes.

if you're not interested in the records content, then just:
- read three bytes
- assert the first is a '5A' (optional, just for checks)
- convert bytes 2,3 to a number 'N'
- skip N bytes
- repeat




-- 
Javier

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