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  2. RPG400-L
  3. July 2006

RE: Binary Bit Map



Thanks to all who replied to my original question.  I am at V5R2 so I just
broke the bit map into 8 fields and used the biton/bitoff opcode.
Consider using %bitand and %bitor to retrieve and set (respectively) the bits. It'll be faster and require less code.
Also, consider coding a constant that corresponds to each bit to make it clear what the bit is for. That'll make your code easier to read. 



I have a somewhat related question.  Some of the fields in the message
need to be coded as Binary Coded Decimal (BCD).  From what I understand
this is a unsigned packed numeric.  Odd length fields are padded with a
leading zero.  So 99,999 would be represented in packed as:   99 99 9F and
in BCD:  09 99 99.


Assuming the BCD field is big-endian:
Create a data structure that overlays a packed field with an unsigned integer field. (make the packed field 15P 0 and the unsigned field 20U 0). Maybe overlay it with an 8A character field as well (depending on what you're doing.)
To convert from BCD to packed, use the char field to store the BCD field into the data structure. Then multiply the unsigned field by 16 and then use %bitor (or BITON if like, or even MLLZO) to set the last nibble to x'0f'.Read the result from the packed field.
To convert from packed to BCD, store the data by setting the packed field, then divide the unsigned field by 16, and retrieve the results from the char field.
If it's little-endian, you'd need to convert it to bigendian when assigning the BCD to the data structure, and convert it back to little endian when extracting the BCD field from the DS. 

Make sense?

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