Random Contiguous Bit Burst Mask

Description

Choose one uniform nonwrapping contiguous positive bit burst start; the mask is left-to-right text, not an encoded integer.

A random construction is defined by its sampling support: positions, permutations, complete tilings, proposal sequences or another explicit set. Uniform choices at one stage do not necessarily make final visible outcomes uniform. A replay seed gives a deterministic sequence; equal values can hide different sampled positions. These tools are for reproducible synthetic examples rather than cryptographic entropy.

Choose one uniform nonwrapping contiguous positive bit burst start; the mask is left-to-right text, not an encoded integer.

When to use this tool

Use this tool to choose one uniform nonwrapping contiguous positive bit burst start; the mask is left-to-right text, not an encoded integer.

How to use the tool and how it works

Enter width, burst, seed using the definitions below.
Run the operation. Resolve input-format errors before interpreting an output.
Read result.seed, result.start, result.mask, using the stated boundary, ordering, sign and absence conventions.

Draw start uniformly in 0…width−burst and set exactly the contiguous interval [start,start+burst) to one in a width-character mask.^[1]

Input field	Meaning and units	Accepted input
width	Integer width, 1–128, in the positions/cells described above.	Finite safe integer satisfying the stated bounds.
burst	Positive contiguous one-bit burst length no greater than width.	Finite safe integer satisfying the stated bounds.
seed	Nonblank replay seed, at most 256 UTF-16 code units; an injected source overrides seeded draws.	Text, at most 8,192 UTF-16 code units; narrower grammar/range rules also apply.

Output field	Interpretation
result	Object containing the fields below.
result.seed	Original supplied seed string; injected-source replay additionally requires that source’s state.
result.start	Inclusive selected interval start or original ring-start index.
result.mask	Left-to-right 0/1 text mask of the requested width.

json

{
  "input": {
    "width": 5,
    "burst": 2,
    "seed": "batch56"
  },
  "output": {
    "result": {
      "seed": "batch56",
      "start": 2,
      "mask": "00110"
    }
  }
}

Limitations and assumptions

width is 1–128 and burst 1–width. This is a fixed-length nonwrapping burst, not independent bit errors.
A nonblank seed of at most 256 UTF-16 code units is required. With ordinary use the seed initializes one deterministic advancing source; an application-injected random source takes precedence and the seed alone then cannot replay the result. Uniformity statements assume independent uniform source draws in [0,1). Source calls are bounded and degenerate injected sources can fail a rejection budget. This is not cryptographically secure.
Every declared outer field is required and unknown outer fields are rejected. Strings and JSON text have size limits, lists are bounded to 128 entries, and JSON nesting/node counts are bounded. Tighter operation-specific bounds stated above take precedence.
Ordinary numeric outputs must be finite and within safe-integer magnitude. Exact large lengths/counts use decimal strings. Original record indexes and code-unit positions are zero-based; span ends are exclusive unless stated otherwise.

Alternative or Complementary methods

Choose a generator whose support matches the intended experiment and retain source-position provenance. Use a separate statistically justified process model or cryptographic source where those properties matter.

References

Tool behavior and example: Random Contiguous Bit Burst Mask — tool.io

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