Ones Complement Dual Zero Equality Tool

Description

Compare one's-complement words with dual-zero equality.

A fixed-width bit pattern and the number it represents are different concepts. Unsigned, two's-complement, one's-complement, sign-magnitude and biased encodings use different sign and zero conventions, so a bit-preserving transformation need not preserve numerical meaning.

Compare one's-complement words with dual-zero equality.

When to use this tool

Use Ones Complement Dual Zero Equality when checking the stated fixed-width representation or encoding convention.

How to use the tool and how it works

Enter left, right, width. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read equal, zero. Inspect equal, zero before interpreting the associated values.

Compare one's-complement words with dual-zero equality. Require width 1..128 and bounded exact operands; equal means identical patterns or both zero/all-ones zero forms, zero flags the dual-zero case.^[1]

One's-complement checksum arithmetic uses end-around carry and has two zero encodings. A single word operation is only part of a complete message checksum.^[2]

Input field	Meaning and units	Accepted input
left	Left	Required. Text; maximum UTF-16 length 8192. Integer syntax: optional + or - and 1-128 decimal digits; leading zeros accepted. Apply the sign restriction above.
right	Right	Required. Text; maximum UTF-16 length 8192. Integer syntax: optional + or - and 1-128 decimal digits; leading zeros accepted. Apply the sign restriction above.
width	Width under the stated bit, interval or geometry convention; apply the field-specific units and bounds.	Required. Safe integer; minimum 1; maximum 128.

Output field	Interpretation	Returned shape
equal	Equal	Required. Boolean.
zero	Zero	Required. Boolean.

json

{
  "input": {
    "left": "0",
    "right": "255",
    "width": 8
  },
  "output": {
    "equal": true,
    "zero": true
  }
}

Limitations and assumptions

Nonzero values still compare literal words; no signed-magnitude or two's-complement equality rule is applied.
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

Choose an explicit representation and width, validate the complete encoded value and use the matching signed or unsigned conversion for the intended numerical interpretation.

References

Calculation and input contract: bitwise/ones-complement-dual-zero-equality — tool.io
Computing the Internet Checksum, RFC 1071 — Internet Engineering Task Force

Similar or alternative tools

Ones Complement Checksum Zero Canonicalizer
Canonicalize either one's-complement zero pattern.
Ones Complement End Around Carry Step
Apply one end-around-carry addition step.