/* * Copyright (c) 1990, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Chris Torek. * * %sccs.include.redist.c% */ #if defined(LIBC_SCCS) && !defined(lint) static char sccsid[] = "@(#)div.c 8.1 (Berkeley) 06/04/93"; #endif /* LIBC_SCCS and not lint */ #include /* div_t */ div_t div(num, denom) int num, denom; { div_t r; r.quot = num / denom; r.rem = num % denom; /* * The ANSI standard says that |r.quot| <= |n/d|, where * n/d is to be computed in infinite precision. In other * words, we should always truncate the quotient towards * 0, never -infinity. * * Machine division and remainer may work either way when * one or both of n or d is negative. If only one is * negative and r.quot has been truncated towards -inf, * r.rem will have the same sign as denom and the opposite * sign of num; if both are negative and r.quot has been * truncated towards -inf, r.rem will be positive (will * have the opposite sign of num). These are considered * `wrong'. * * If both are num and denom are positive, r will always * be positive. * * This all boils down to: * if num >= 0, but r.rem < 0, we got the wrong answer. * In that case, to get the right answer, add 1 to r.quot and * subtract denom from r.rem. */ if (num >= 0 && r.rem < 0) { r.quot++; r.rem -= denom; } return (r); }