Description
Fill low bits through the least-significant set bit.
Bit positions are usually counted from the least-significant bit, while a displayed binary string has its own left-to-right indexing convention. Masks, fields and parity predicates describe a selected region or pattern; local agreement does not validate a complete encoded record.
Fill low bits through the least-significant set bit.
When to use this tool
Use Bitmask Trailing Run Fill when checking the stated mask, field, parity or bit-index convention.
How to use the tool and how it works
- Enter word, width. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read value. Use the output convention below.
Fill low bits through the least-significant set bit. Require width 1..32 and bounded word; value = (word OR (word-1)) AND width mask.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| word | Word | Required. Safe integer; minimum 0. |
| width | Width under the stated bit, interval or geometry convention; apply the field-specific units and bounds. | Required. Safe integer; minimum 1; maximum 32. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| value | word OR its wrapped predecessor; a zero word produces an all-one result. | Required. Safe integer. |
{
"input": {
"word": 40,
"width": 8
},
"output": {
"value": 47
}
}Limitations and assumptions
- For input zero the wrapped predecessor yields all ones, an explicit edge convention rather than no change.
- 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 bit order, word width and missing-position policy; use the complete record format and appropriate parsing or checksum methods for full validation.
References
Similar or alternative tools
- Bitmask Run Start Boundary Mask
Return low boundaries of one-bit runs.
- Bitmask Run End Boundary Mask
Return high boundaries of one-bit runs.