BlockEncoder

class iced_x86.BlockEncoder

Encodes instructions

Encoder can only encode one instruction at a time. This class can encode any number of instructions and can also fix short branches if the target is too far away.

It will fail if there’s an instruction with an RIP-relative operand ([rip+123h]) and the target is too far away. A workaround is to use a new base RIP of the encoded instructions that is close (+/-2GB) to the original location.

Parameters:

• bitness (int) – 16, 32 or 64

• fix_branches (bool) – (default = True) Fix branches (eg. convert short to near branches if the target is too far away)

Raises:

ValueError – If bitness is invalid

Examples:

from iced_x86 import *

data = b"\x86\x64\x32\x16\xF0\xF2\x83\x00\x5A\x62\xC1\xFE\xCB\x6F\xD3"
decoder = Decoder(64, data, ip=0x1234_5678)

instrs = [instr for instr in decoder]

encoder = BlockEncoder(64)
# Add an instruction
encoder.add(instrs[0])
# Add more instructions
encoder.add_many(instrs[1:])
try:
    # Encode all added instructions and get the raw bytes
    raw_data = encoder.encode(0x3456_789A)
except ValueError as ex:
    print("Could not encode all instructions")
    raise

# It has no IP-relative instructions (eg. branches or [rip+xxx] ops)
# so the result should be identical to the original code.
assert data == raw_data

add(instruction)

Adds an instruction that will be encoded when BlockEncoder.encode is called.

The input instruction can be a decoded instruction or an instruction created by the user, eg. Instruction.create*() methods.

Parameters:

instruction (Instruction) – Next instruction to encode

add_many(instructions)

Adds instructions that will be encoded when BlockEncoder.encode is called.

Parameters:

instructions (List[Instruction]) – Next instructions to encode

encode(rip)

Encodes all instructions added by BlockEncoder.add/BlockEncoder.add_many and returns the raw bytes

Parameters:

rip (int) – (u64) Base IP of all encoded instructions

Returns:

All encoded instructions

Return type:

bytes

Raises:

ValueError – If one or more instructions couldn’t be encoded