integers

panel 1:

To decode bytes as integers, we need to know 3 things: 1. the integer’s size (8 bit, 16 bit, 32 bit, or 64 bit) 2. is it little or big endian? 3. is it signed or unsigned?

panel 2:

how signed integers work is the hardest part) to understand (I only learned how it works a couple months ago!). Just knowing that unsigned and signed integers are different will take you a long way.

2 bytes, 3 interpretations

254 | 0

We could interpret these 2 bytes as: 1. 254 (little endian) 2. 65024 (big endian, unsigned) 3. -512 (big endian, signed)

how you decode bytes depends on the context

• in a program’s memory, the type of the variable tells you the integer’s size and if it’s signed/unsigned
• your CPU determines if integers are big or little endian (you don’t have a choice)
• for a binary network protocol (like DNS), the specification (for DNS, that’s RFC 1035) will tell you how to decode the bytes

examples of types

• in Rust, an i64 is a signed 64-bit integer
• in Go, a uint32 is an unsigned 32-bit integer
• in C, a short is usually a signed 16-bit integer, depending on the platform