CODEWITHSUNDEEP
specificationsbit
user773737
user773737

Reputation:

What is this table called and how do I read it?

I'm reading the powerpoint specification and I came across a table like this:

enter image description here

Do tables like these have a name? How do I read this?

I'm pretty sure it means that the first 4 bits identifies the recVer and the next 12 identifies the recInstance, but what about recLen? Do all 32 bits pull double-duty and identify the recLen or does that mean the next 32 bits do that?

Upvotes: 0

Views: 59

Answers (3)

Amit
Amit

Reputation: 46351

Not sure about an official/standard name, but this looks like a record layout map.

You read it left to right, every box is a single bit.

The record is composed of

  1. 4 bits recVer
  2. 12 bits recInstance
  3. 16 bits recType
  4. 32 bits recLen

Upvotes: 0

hookenz
hookenz

Reputation: 38967

This is just part of the binary format for the powerpoint file. the 0,1,2 etc are the bit numbers. So you can see bit's 0 - 3 inclusive are the recVer etc.

The specification will tell you want recVer, recInstance and recType mean. I think recLen should be obvious but it'll be in the spec.

To read it, you'd read in the bytes and then do bit manipulation to decode those fields. You don't say what language you'll be using but you can do bit manipulation in a number of languages.

Upvotes: 0

clcto
clcto

Reputation: 9648

It looks like some type of packet header. The numbers at the top are the bit position. It is read left to right, top to bottom, so it is telling you that the header is made up of 4 bits interpreted as the recVer, followed by 12 bits that is interpreted as recInstance, followed by 16 bits that is the recType, followed by 32 bits which is the recLen.

This is a common way to show the header structure, as can be seen on Wikipedia's TCP page.

Upvotes: 2

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