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 |
