Class CScriptNum

test/functional/test_framework/script.py:472–509

# This is used, eg, for blockchain heights in coinbase scripts (bip34)
class CScriptNum:
    __slots__ = ("value",)

    def __init__(self, d=0):
        self.value = d

    @staticmethod
    def encode(obj):
        val = obj.value
        r = bytearray(0)
        if val == 0:
            return bytes(r)
        neg = val < 0
        absvalue = -val if neg else val
        while (absvalue):
            r.append(absvalue & 0xff)
            absvalue >>= 8
        if r[-1] & 0x80:
            r.append(0x80 if neg else 0)
        elif neg:
            r[-1] |= 0x80
        return bytes([len(r)]) + r

    @staticmethod
    def decode(vch):
        result = 0
        # We assume valid push_size and minimal encoding
        value = vch[1:]
        if len(value) == 0:
            return result
        for i, byte in enumerate(value):
            result |= int(byte) << 8 * i
        if value[-1] >= 0x80:
            # Mask for all but the highest result bit
            num_mask = (2**(len(value) * 8) - 1) >> 1
            result &= num_mask
            result *= -1
        return result

class CScript(bytes):
    """Serialized script