COMP-1 And Comp-2 representation

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COMP-1 And Comp-2 representation

Postby coollearner » Sat Jun 05, 2010 6:40 pm

Hi All,

I have referred the following link ... 0820210412

in this link :

Internal floating point
+ 1234
43 4D 20 00

- 1234
C3 4D 20 00

+ 1234
43 4D 20 00 00 00 00 00

- 1234
C3 4D 20 00 00 00 00 00

I want to know how the conversion happened?
The hexvalue of 1234 is 4D2. How did the 43 4D 20 00 got generated. Please explain
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Re: COMP-1 And Comp-2 representation


Re: COMP-1 And Comp-2 representation

Postby enrico-sorichetti » Sat Jun 05, 2010 7:15 pm

how do You expect to make a career in it with such a lack of ingenuity :D

please reread and uderstand the manual or better a bit of number representation theory
comp-1 and comp-2 as the manual says are floating point representations

see the pattern for binary representation of a positive 1234 ,
search for a similar pattern in the comp-1 representation
and meditate on the meaning of mantissa and exponent for floating point representation
When I tell somebody to RTFM or STFW I usually have the page open in another tab/window of my browser,
so that I am sure that the information requested can be reached with a very small effort
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Re: COMP-1 And Comp-2 representation

Postby Robert Sample » Sat Jun 05, 2010 8:01 pm

From the very manual that you have a link to in your post: Internal floating-point (COMP-1 and COMP-2) items

COMP-1 refers to short floating-point format and COMP-2 refers to long floating-point format, which occupy 4 and 8 bytes of storage, respectively. The leftmost bit contains the sign and the next 7 bits contain the exponent; the remaining 3 or 7 bytes contain the mantissa.

COMP-1 and COMP-2 data items are stored in zSeries® hexadecimal format.
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