Bitwise: Word Shift Out Bit Mask Tool

Description

Return bits shifted out of one word.

Fixed-width arithmetic can wrap, saturate, shift in sign bits or expose discarded bits. Carry, borrow and signed overflow describe different conditions; a local rounding decision or guard/sticky triplet is one part of an arithmetic operation rather than a complete floating-point result.

Return bits shifted out of one word.

When to use this tool

Use Bitwise: Word Shift Out Bit Mask when evaluating the stated shift, arithmetic flag or rounding convention.

How to use the tool and how it works

Enter word, width, shift, direction. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read result. Expand result to inspect the returned fields.

Return bits shifted out of one word. Validate bounded word and shift in [0,width]; left takes the highest shift bits, right takes the lowest shift bits; return the compacted decimal word and shiftedOutCount = shift.^[1]

Input field	Meaning and units	Accepted input
word	Word	Required. Text. Integer syntax: optional + or - and 1-128 decimal digits; leading zeros accepted. Apply the sign restriction above. Implementation limit: 8192 Unicode code points and 16384 UTF-16 code units. Word value must satisfy 0 <= value < 2^width.
width	Width under the stated bit, interval or geometry convention; apply the field-specific units and bounds.	Required. Safe integer. Fixed-word implementation domain: whole width 1-128 bits.
shift	Shift	Required. Safe integer. Calculation range: 0 through width, inclusive.
direction	Direction	Required. Text; one of "left", "right". Implementation limit: 8192 Unicode code points and 16384 UTF-16 code units.

Output field	Interpretation	Returned shape
result	Returned calculated value or nested object under the stated output convention.	Required. Object.
result.shiftedOutWord	Compact discarded low-bit value, not a mask retaining original bit positions.	Calculated result member: string.
result.shiftedOutCount	Shifted Out Count	Calculated result member: number.

json

{
  "input": {
    "word": "129",
    "width": 8,
    "shift": 2,
    "direction": "left"
  },
  "output": {
    "result": {
      "shiftedOutWord": "2",
      "shiftedOutCount": 2
    }
  }
}

Limitations and assumptions

The output does not preserve original bit positions or apply the shift to the remaining word; zero and full-width shifts are allowed.
Outputs are nested inside result. 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

Use a complete arithmetic operation with explicit width, signedness, overflow and rounding policy; keep exact integer text when values exceed ordinary numeric precision.

References

Calculation and input contract: bitwise/word-shift-out-bit-mask — tool.io

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