def write_uvarint(w: Writer, n: int) -> None:
ensure(0 <= n <= 0xFFFF_FFFF_FFFF_FFFF)
shifted = 1
while shifted:
shifted = n >> 7
byte = (n & 0x7F) | (0x80 if shifted else 0x00)
w.append(byte)
n = shifted
def write_uint64_be(w: Writer, n: int) -> int:
ensure(0 <= n <= 0xFFFFFFFFFFFFFFFF)
w.append((n >> 56) & 0xFF)
w.append((n >> 48) & 0xFF)
w.append((n >> 40) & 0xFF)
w.append((n >> 32) & 0xFF)
w.append((n >> 24) & 0xFF)
w.append((n >> 16) & 0xFF)
w.append((n >> 8) & 0xFF)
w.append(n & 0xFF)
return 8
def write_int(w: Writer, number: bytes) -> None:
i = 0
while i < len(number) and number[i] == 0:
i += 1
length = len(number) - i
w.append(0x02)
if length == 0 or number[i] >= 0x80:
w.extend(encode_length(length + 1))
w.append(0x00)
else:
w.extend(encode_length(length))
w.extend(memoryview(number)[i:])
def write_header(
w: Writer,
length: int,
header_byte: int,
data_start: bytes | None = None,
) -> None:
if length == 1 and data_start is not None and data_start[0] <= 0x7F:
# no header when encoding one byte below 0x80
pass
elif length <= 55:
w.append(header_byte + length)
else:
encoded_length = int_to_bytes(length)
w.append(header_byte + 55 + len(encoded_length))
w.extend(encoded_length)
def write_varint(w: Writer, val: int) -> None:
"""
Implements variable-length int encoding from Ripple.
See: https://ripple.com/wiki/Binary_Format#Variable_Length_Data_Encoding
"""
if val < 0:
raise ValueError("Only non-negative integers are supported")
elif val < 192:
w.append(val)
elif val <= 12480:
val -= 193
w.append(193 + rshift(val, 8))
w.append(val & 0xFF)
elif val <= 918744:
val -= 12481
w.append(241 + rshift(val, 16))
w.append(rshift(val, 8) & 0xFF)
w.append(val & 0xFF)
else:
raise ValueError("Value is too large")
def write_compact_size(w: Writer, n: int) -> None:
ensure(0 <= n <= 0xFFFF_FFFF)
if n < 253:
w.append(n & 0xFF)
elif n < 0x1_0000:
w.append(253)
write_uint16_le(w, n)
elif n < 0x1_0000_0000:
w.append(254)
write_uint32_le(w, n)
else:
w.append(255)
write_uint64_le(w, n)
def write_uint32_be(w: Writer, n: int) -> int:
ensure(0 <= n <= 0xFFFFFFFF)
w.append((n >> 24) & 0xFF)
w.append((n >> 16) & 0xFF)
w.append((n >> 8) & 0xFF)
w.append(n & 0xFF)
return 4
def write_type(w: Writer, field: RippleField) -> None:
if field.key <= 0xF:
w.append((field.type << 4) | field.key)
else:
# this concerns two-bytes fields such as lastLedgerSequence
w.append(field.type << 4)
w.append(field.key)
def write_uint16_le(w: Writer, n: int) -> int:
ensure(0 <= n <= 0xFFFF)
w.append(n & 0xFF)
w.append((n >> 8) & 0xFF)
return 2
def write_uint8(w: Writer, n: int) -> int:
ensure(0 <= n <= 0xFF)
w.append(n)
return 1
def write_bitcoin_varint(w: Writer, n: int) -> None:
ensure(0 <= n <= 0xFFFF_FFFF)
if n < 253:
w.append(n & 0xFF)
elif n < 0x1_0000:
w.append(253)
w.append(n & 0xFF)
w.append((n >> 8) & 0xFF)
else:
w.append(254)
w.append(n & 0xFF)
w.append((n >> 8) & 0xFF)
w.append((n >> 16) & 0xFF)
w.append((n >> 24) & 0xFF)
