Fixed Point Division and Rescale

Exact raw fixed-point division and rescaling, truncating toward zero while retaining signed remainder evidence.

Description

Exact raw fixed-point division and rescaling, truncating toward zero while retaining signed remainder evidence.

Dividing stored fixed-point integers requires restoring one factor of the fractional scale. Integer division also needs a sign convention.

When to use this tool

Exact raw fixed-point division and rescaling, truncating toward zero while retaining signed remainder evidence.

  • Prepare the supplied left, right, fractionalBits 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

  1. Enter left, right, fractionalBits. Use the exact text syntax, units and index conventions explained below.
  2. Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
  3. Read result.integer, result.remainder, result.divisor. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.

Parse left/right as exact integers, require nonzero right and fractionalBits 0 to 128. Divide left*2^fractionalBits by right, returning quotient integer, signed remainder and divisor as decimal text.1

Input fieldMeaning and representationAccepted input
leftExact decimal integer text; keep it quoted in JSON rather than converting through a floating-point number.Optional leading + or - and 1 to 256 decimal digits; no whitespace
rightExact decimal integer text; keep it quoted in JSON rather than converting through a floating-point number.Optional leading + or - and 1 to 256 decimal digits; no whitespace
fractionalBitsfractional bits.Integer from 0 to 128 inclusive
Output fieldInterpretation
resultObject containing the named outputs below.
result.integerExact decimal integer text under the operation described above.
result.remainderThe remainder value under the stated formula or text convention.
result.divisorThe divisor value under the stated formula or text convention.
json
{
  "input": {
    "left": "6",
    "right": "3",
    "fractionalBits": 2
  },
  "output": {
    "result": {
      "integer": "8",
      "remainder": "0",
      "divisor": "3"
    }
  }
}

Limitations and assumptions

  • Division truncates toward zero; remainder follows the scaled numerator's sign. No rounding, saturation or output-width overflow policy is applied.
  • Exact decimal-spelling operations require digits before the optional decimal point and allow a signed exponent. Decimal text is bounded to 256 code units and effective scale to minus 256 through 256; integer-string fields allow a sign and up to 256 digits.
  • Every declared top-level field is required and unexpected fields are rejected. Numeric inputs must be finite; ordinary text fields are bounded to 8,192 UTF-16 code units, with tighter operation-specific limits where stated.
  • Lists are limited to 128 entries. JSON text must meet bounded size and depth checks, and numeric outputs beyond the safe finite magnitude are rejected. Exact large integers use decimal strings.
  • Indexes are zero-based and spans have an exclusive end unless explicitly stated otherwise. A valid false, null or empty-list result is distinct from malformed input.

Alternative or Complementary methods

Preserve decimal and integer strings when exact comparisons matter. Select signedness, scale, rounding and overflow policies separately, and use the matching encoder/decoder rather than a floating-point approximation.

References

  1. Tool behavior and example: Fixed Point Division and Rescale — tool.io

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