specification/protocol/p2p/compact__int.md

A "compact int" is serialized as follows:

*If the number < 253, store it in 1 byte *If the number fits in 16 bits: store a 1 byte value 253, and the 2 byte little-endian number.

0	1	2
0xfd	val&255	val>>8

• If the number fits in 32 bits (but not 8 or 16): store a 1 byte value 254, and the 4 byte little-endian number

0	1	2	3	4
0xfe	val&255	(val>>8)&255	(val>>16)&255	(val>>24)&255

• If the number fits in 64 bits (but not 8, 16, or 32): store a 1 byte value 255 and the 8 byte little-endian number

0	1	2	3	4	5	6	7	8
0xff	val&255	val>>8	val>>16	val>>24	val>>32	val>>40	val>>48	val>>56