rfcs/0023-dao-deposit-withdraw.md at master · nervosnetwork/rfcs · GitHub says the field encodes 4 integers, how to extract them?
As the chapter Calculation in the RFC23 says, the DAO field packs 4 integers. Each integer is encoded as an unsigned 64-bit little-endian number. That’s 8 bytes for each integer. The DAO field has 32 bytes, so it just concatenates the integers, in this order: C_i , AR_i, S_i, and U_i.
For example, in the mainnet, the DAO field of the genesis block is 0x8874337e541ea12e0000c16ff286230029bfa3320800000000710b00c0fefe06.
We’ll get the serialized integers by splitting it into 4 groups, where each group has 8 bytes. These groups corresponds to C_i, AR_i, S_i, and U_i from left to right.
-
C_i:0x8874337e541ea12e -
AR_i:0x0000c16ff2862300 -
S_i:0x29bfa33208000000 -
U_i:0x00710b00c0fefe06
Then we can decode integers from the binaries, which gives us:
-
C_i: 3360000145238488200 Shannons, which is about 33.6 billion issued CKB (1 CKB = 10^8 Shannons). -
AR_i: 10000000000000000, which is the original value 1 multiplying 10^{16}. -
S_i: 35209330473 Shannons -
U_i: 504120308900000000 Shannons, which is about 5 billion bytes occupied in the genesis block (1 byte = 1 CKB = 10^8 Shannons).
Following is the example Python code to extract the values:
import struct
# The format string `<4q` means:
# < - little endian
# 4 - there are 4 integers
# q - each having 8 bytes
print(struct.unpack('<4q', bytes.fromhex('8874337e541ea12e0000c16ff286230029bfa3320800000000710b00c0fefe06')))
# => (3360000145238488200, 10000000000000000, 35209330473, 504120308900000000)
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