BITLSHIFT

What it does

BITLSHIFT(number, shift_amount)

BITLSHIFT(number, shift_amount) moves an integer’s binary digits left. A negative count reverses the direction. The ordinary left shift corresponds to multiplication by a power of two.

Try it

=BITLSHIFT(13,2) returns 52. Binary 1101 becomes 110100 after appending two zeros. A count of -2 shifts right.

Quirks

The number must be an integer in 0..2^48-1; fractional numbers give #NUM!. The count is truncated. Documentation rejects count magnitudes above 53. Recorded build-20430 rules add exceptions: zero bypasses the finite count-range check, and admitted counts of magnitude 49 through 53 return zero in either direction.

How to implement

Validate the number first and require a finite count. Return zero immediately for a zero number. Otherwise truncate the count and reject magnitudes above 53; magnitudes 49 through 53 return zero. Convert the function and count sign to a left/right direction. Before a left shift of k, check number <= (2^48-1)>>k; reject overflow with #NUM!. A right shift discards the low bits. Return the resulting integer as a worksheet number. These shortcuts are recorded compatibility behaviour, and should not be replaced by a host language’s masked shift-count semantics.

Rust code

23 bitlshift "BITLSHIFT" (2, 2) [V "number", V "shift_amount"] |s, a, sv| {
    bits(s, a, k::bitlshift_fn::bitlshift_kernel)
}

pub fn bitlshift_kernel(number: f64, shift: f64) -> Result<f64, WorksheetErrorCode> {
    bit_shift_kernel(number, shift, true)
}

No implementation has been published with a Handbook test suite for this function.

Version differences

The recorded environments below distinguish a reading from a same-input comparison. Counts describe captured inputs in each environment; overlapping captures and comparisons are not totals of unique worksheet calls.

The record contains no same-input comparison between these environments. Reading different inputs on different builds does not establish either a version change or cross-build agreement.

Recorded environments and comparison details.

Alternatives

BITRSHIFT changes the default direction. BITAND extracts a bit field after shifting.

Named variants

No named variants are recorded yet.