Protocol Buffers Zigzag Signed Scalar Tool

Description

Map one exact signed integer to its unsigned ZigZag value under a declared bit width.

Protocol Buffer integer fields separate a numeric key, signed-value mapping and byte representation. Varint groups carry seven payload bits plus continuation, while ZigZag and sign-extended integer types represent negative values differently.

Map one exact signed integer to its unsigned ZigZag value under a declared bit width.

When to use this tool

Use Protocol Buffers Zigzag Signed Scalar when inspecting one supplied protobuf integer or key-encoding component.

How to use the tool and how it works

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

Require whole bits in [1,64] and an exact signed decimal integer within [-2^(bits-1),2^(bits-1)-1]. Return unsignedDecimal = 2*n for n >= 0, otherwise -2*n-1, as exact decimal text.^[1]

Protobuf separates keys, varints, fixed-width payloads and signed mappings. A local field transformation does not encode a complete message.^[2]

Input field	Meaning and units	Accepted input
signedDecimal	Exact signed integer text, with its range determined by bits.	Required. Text; maximum UTF-16 length 8192. Integer syntax: optional + or - and 1-128 decimal digits; leading zeros accepted. Apply the sign restriction above.
bits	Signed bit width from one through 64.	Required. Safe integer; minimum 1; maximum 64.

Output field	Interpretation	Returned shape
unsignedDecimal	Unsigned Decimal	Required. Text; maximum UTF-16 length 8192.

json

{
  "input": {
    "signedDecimal": "-2",
    "bits": 32
  },
  "output": {
    "unsignedDecimal": "3"
  }
}

Limitations and assumptions

This is ZigZag mapping only, not the subsequent varint bytes. The declared signed width is enforced; numeric floating-point input is not substituted for decimal text.
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.
Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Use a conforming complete serializer and message schema for full wire encoding, payload validation and interoperability.

References

Calculation and input contract: encode/protobuf-zigzag-signed-scalar — tool.io
Protocol Buffers wire encoding — Protocol Buffers

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