Leftshifted

Leftshifted is a term used to describe data or values that have undergone a left shift operation, typically in computing or digital logic. It can refer to the resulting bit pattern as well as the act of shifting. The concept is common in low-level programming, hardware design, and data encoding.

In fixed-width binary representations, a left shift moves each bit to a higher-significance position by a specified number of places. Bits that move past the most-significant end are discarded, and the vacated least-significant positions are filled with zeros. For example, shifting the 8-bit value 00101101 left by 2 results in 10110100. For unsigned integers, a left shift by n is equivalent to multiplying by 2^n modulo the width of the type. For signed integers, the behavior can involve overflow, and multiple languages treat such overflow differently (some define wraparound, others treat it as undefined).

Left shifting is distinct from right shifting, where bits are moved toward lower significance and can be either logical (zero-fill) or arithmetic (sign-extension) depending on the language. There is no separate arithmetic left shift in common terminology; the left-shift operation is generally the same for signed and unsigned values, with overflow handling governed by language rules.

Applications for leftshifted data include fast multiplication by powers of two, bit packing and field alignment, and efficient data encoding or transformation in both software and hardware. When applying left shifts, it is important to consider the data width and potential overflow, as these factors determine the validity and safety of the operation. See also: right shift, bitwise operations, bit masking.