Length Field Frame Splitter

Split a complete length-field byte stream with explicit 1–4 byte unsigned payload lengths and byte order; truncation is rejected, no checksum or sync inference.

Description

Split a complete length-field byte stream with explicit 1–4 byte unsigned payload lengths and byte order; truncation is rejected, no checksum or sync inference.

Length-prefixed frame splitting reads consecutive complete records under a declared width and byte order.

When to use this tool

Split a complete length-field byte stream with explicit 1–4 byte unsigned payload lengths and byte order; truncation is rejected, no checksum or sync inference.

Prepare the supplied bytes, lengthBytes, littleEndian fields for this operation.
Compare the complete example with the representation used by your own input before carrying the result into another step.

How to use the tool and how it works

Enter bytes, lengthBytes, littleEndian. Use the exact text syntax, units and index conventions explained below.
Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
Read result.frames. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.

With lengthBytes from 1 to 4, read an unsigned length at the cursor, require the complete payload, append it and repeat to the exact end. Truncated prefixes or payloads are errors.^[1]

Input field	Meaning and representation	Accepted input
bytes	bytes.	List of integers from 0 to 255; at most 128 bytes
lengthBytes	length bytes.	Integer from 1 to 4 inclusive
littleEndian	Explicit choice for little endian; supply a boolean rather than a text label.	true or false

Output field	Interpretation
result	Object containing the named outputs below.
result.frames	The frames list in the ordering and representation described above.

json

{
  "input": {
    "bytes": [
      2,
      1,
      2,
      1,
      3
    ],
    "lengthBytes": 1,
    "littleEndian": false
  },
  "output": {
    "result": {
      "frames": [
        [
          1,
          2
        ],
        [
          3
        ]
      ]
    }
  }
}

Limitations and assumptions

The length excludes its own prefix. No incomplete carry is retained, no trailer is assumed and no I/O or checksum validation occurs.
All declared input fields are required and unexpected top-level fields are rejected. Numbers must be finite; lists are limited to 128 entries and ordinary text fields to 8,192 UTF-16 code units, with tighter limits where stated.
JSON text inputs must parse within bounded nesting and size limits. Numeric outputs outside the safe finite range are rejected; large exact integer results use decimal strings. Indexes and half-open spans are zero-based unless a rank is explicitly described as one-based.

Alternative or Complementary methods

Use a stateful protocol parser when processing partial streams or validating complete packets. Retain the declared prefix width, byte order and payload-versus-frame boundary convention when composing these operations.

References

Tool behavior and example: Length Field Frame Splitter — tool.io

Similar or alternative tools

Length Field Frame Joiner
Join bounded byte payload frames with explicit unsigned length prefixes and byte order; output stream is limited to 128 bytes.
Byte Frame Prefix Length Audit
Compare a leading unsigned byte length field against the complete remaining frame payload; mismatch is evidence, not a thrown truncation error.