Description
Sign-extend a word from source width to target width.
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.
Sign-extend a word from source width to target width.
When to use this tool
Use Signed Word Sign Extension Gap when checking the stated fixed-width representation or encoding convention.
How to use the tool and how it works
- Enter wordDecimal, sourceWidth, targetWidth. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read extendedDecimal, addedBitValueDecimal. Use the output convention below.
Sign-extend a word from source width to target width. Require 1 <= sourceWidth <= targetWidth <= 256 and bounded exact decimal word; if source sign bit set, add 2^targetWidth-2^sourceWidth, returning extended and added-bit values as decimal text.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| wordDecimal | Word Decimal | Required. Text; maximum UTF-16 length 8192. Integer syntax: optional + or - and 1-128 decimal digits; leading zeros accepted. Apply the sign restriction above. |
| sourceWidth | Source Width | Required. Safe integer; minimum 1; maximum 256. |
| targetWidth | Target Width | Required. Safe integer; maximum 256. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| extendedDecimal | Extended Decimal | Required. Text; maximum UTF-16 length 8192. |
| addedBitValueDecimal | Added Bit Value Decimal | Required. Text; maximum UTF-16 length 8192. |
{
"input": {
"wordDecimal": "255",
"sourceWidth": 8,
"targetWidth": 16
},
"output": {
"extendedDecimal": "65535",
"addedBitValueDecimal": "65280"
}
}Limitations and assumptions
- The result is the unsigned pattern of the extended signed word; this is not zero extension or a byte-order transformation.
- 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
Similar or alternative tools
- Signed Word Negation Fixed Point
Check fixed points of modular signed negation.
- Signed Magnitude Add Sign Conflict
Compare signed-magnitude operands for opposing nonzero signs.