Bit String Cyclic Window
Extract a bounded circular bit window from a signed starting position, allowing repeated cycles; empty source permits only an empty window.
Description
Extract a bounded circular bit window from a signed starting position, allowing repeated cycles; empty source permits only an empty window.
A cyclic bit window can extend beyond the source's end and repeat its contents. Negative starts wrap through the same cycle.
When to use this tool
Extract a bounded circular bit window from a signed starting position, allowing repeated cycles; empty source permits only an empty window.
- Prepare the supplied bits, start, length 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 bits, start, length. 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.bits. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.
For length from 0 to 128, read source position (start plus j) modulo source length for each output bit, using nonnegative modulo. Empty source is allowed only for zero output length.1
| Input field | Meaning and representation | Accepted input |
|---|---|---|
| bits | bits. | Binary text containing only 0 and 1; at most 128 characters |
| start | start. | Integer from -1e9 to 1e9 inclusive |
| length | length. | Integer from 0 to 128 inclusive |
| Output field | Interpretation |
|---|---|
| result | Object containing the named outputs below. |
| result.bits | The bits value under the stated formula or text convention. |
{
"input": {
"bits": "101",
"start": -1,
"length": 5
},
"output": {
"result": {
"bits": "11011"
}
}
}Limitations and assumptions
- This repeats literal bits without changing their representation. start is bounded to plus or minus one billion.
- Every bitstring is at most 128 characters and contains only literal zero and one.
- 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
Choose a packed-integer or textual-bit representation deliberately before combining operations. Preserve the documented index direction, width and exclusive boundaries; do not substitute a rank query for select.
References
Similar or alternative tools
- Bit String Circular One Runs
Inventory circular one-bit runs with modular starting positions and lengths; all-ones has one full-cycle run and empty/all-zero strings have none.
- Bit String Contained Mask Check
Check exact equal-width bit-mask left containment in right at each string position; no implicit padding or integer coercion.