modsi

Modsi is a term encountered in programming to denote a function or macro that computes the modulo of a signed integer, or more generally a signed-int variant of the modulo operation. It is not a standardized function defined by language specifications; its exact behavior depends on the codebase or library in which it appears. The naming convention often uses “si” to indicate signed integer.

In mathematical terms, modulus returns a non-negative remainder when dividing by a positive modulus. For signed integers, some languages define a remainder that can be negative, so modsi implementations typically adjust the result to be within the range [0, m). A common approach is to compute r = a % m and, if r is negative, return r + m (assuming m > 0). For example, in C-like pseudocode: int modsi(int a, int m) { int r = a % m; if (r < 0) r += m; return r; }

Usage considerations include ensuring the modulus m is nonzero and understanding platform-specific behavior of the remainder operator for negative operands. Edge cases, such as when a is at the limits of the integer range or when m is negative, may require additional handling or explicit documentation in the codebase. Because modsi is not a standard library function, its exact semantics can vary between projects, so developers should consult local documentation or source code to confirm its intended behavior.

Etymology-wise, the suffix “si” commonly signals signed integer in programming naming conventions. Modsi is typically part of a family of helpers that implement portable modular arithmetic, contrasting with the plain remainder operator or with unsigned versions of modulus functions. See also modulus operation, remainder, and signed integer arithmetic.