CBOR Negative Integer Initial Argument Tool

Description

Return CBOR’s exact unsigned argument for one supported negative integer.

CBOR combines a three-bit major type with additional information in an initial byte. Negative integers use an unsigned argument related by -1-n, while simple values and break markers have distinct meanings.

Return CBOR’s exact unsigned argument for one supported negative integer.

When to use this tool

Use CBOR Negative Integer Initial Argument when checking one CBOR initial-byte, simple-value or negative-integer argument.

How to use the tool and how it works

Enter integer. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read argument. Use the output convention below.

Parse an exact negative decimal integer n in [-18446744073709551616,-1]. Return argument = -1-n as exact decimal text.^[1]

CBOR type and argument conventions determine the encoded value. Constructing one argument or initial byte does not validate a full item.^[2]

Input field	Meaning and units	Accepted input
integer	Integer	Required. Text; maximum UTF-16 length 8192. Integer syntax: optional + or - and 1-128 decimal digits; leading zeros accepted. Apply the sign restriction above.

Output field	Interpretation	Returned shape
argument	Argument	Required. Text; maximum UTF-16 length 8192.

json

{
  "input": {
    "integer": "-25"
  },
  "output": {
    "argument": "24"
  }
}

Limitations and assumptions

This returns the unsigned argument for CBOR major type 1, not the integer's absolute value or its complete byte encoding. Larger negative bignums need a different representation.
Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.

Alternative or Complementary methods

Use a complete CBOR encoder or decoder to check type-specific validity, following arguments and complete item structure.

References

Calculation and input contract: encode/cbor-negative-integer-initial-argument — tool.io
Concise Binary Object Representation: RFC 8949 — Internet Engineering Task Force

Similar or alternative tools

CBOR Small Integer Initial Octet
Return octet = value+(negative ? 32 : 0).
CBOR Simple Value Initial Octet
Encode a CBOR simple-value code while rejecting reserved values 24 through 31.