Hi Neil.

02-Nov-03 10:43:02, Neil Heller wrote

 NH> I wrote communication programs to download electrical usage
 NH> information from industrial meters.  Those meters are currently
 NH> being produced.  One of them stored all values in BCD, and
 NH> transmitted them as such.  In a situation like that, the receiver
 NH> doesn't have much choice.

 NH> I did a bunch of BCD work with MSC6, but I ended up having to roll my
 NH> own library.  Basically it involved shifting for one side of the byte
 NH> and masking for the other.  The BCD would then be translated into
 NH> integer types and the application would proceed from there.  Division
 NH> was a real bear, though.

// convert the bcd to to ascii
  sprintf(buf,"%x",bcd);   // not portable - but something likethat...
// convert ascii to two's compliment
  number=atol(buf);

probably less efficient than direct manipulating, but if the need is speed
use a lookup tables to convert it a byte (or more?) at a time...

    number=0;
    for (i=0; i< sizeof_bcd;i++) number=number*100+bcdval[bcd[i]];

or declare a struct with bitfields

struct bcd_value {
 unsigned digit3:4;
 unsigned digit2:4;
 unsigned digit1:4;
 unsigned digit0:4;
 }

then C will do the bit-masking for you....

 -=> Bye <=-

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