1*4882a593Smuzhiyun /* Copyright (C) 1992, 1997 Free Software Foundation, Inc.
2*4882a593Smuzhiyun This file is part of the GNU C Library.
3*4882a593Smuzhiyun
4*4882a593Smuzhiyun * SPDX-License-Identifier: LGPL-2.0+
5*4882a593Smuzhiyun */
6*4882a593Smuzhiyun
7*4882a593Smuzhiyun typedef struct {
8*4882a593Smuzhiyun long quot;
9*4882a593Smuzhiyun long rem;
10*4882a593Smuzhiyun } ldiv_t;
11*4882a593Smuzhiyun /* Return the `ldiv_t' representation of NUMER over DENOM. */
12*4882a593Smuzhiyun ldiv_t
ldiv(long int numer,long int denom)13*4882a593Smuzhiyun ldiv (long int numer, long int denom)
14*4882a593Smuzhiyun {
15*4882a593Smuzhiyun ldiv_t result;
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun result.quot = numer / denom;
18*4882a593Smuzhiyun result.rem = numer % denom;
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun /* The ANSI standard says that |QUOT| <= |NUMER / DENOM|, where
21*4882a593Smuzhiyun NUMER / DENOM is to be computed in infinite precision. In
22*4882a593Smuzhiyun other words, we should always truncate the quotient towards
23*4882a593Smuzhiyun zero, never -infinity. Machine division and remainer may
24*4882a593Smuzhiyun work either way when one or both of NUMER or DENOM is
25*4882a593Smuzhiyun negative. If only one is negative and QUOT has been
26*4882a593Smuzhiyun truncated towards -infinity, REM will have the same sign as
27*4882a593Smuzhiyun DENOM and the opposite sign of NUMER; if both are negative
28*4882a593Smuzhiyun and QUOT has been truncated towards -infinity, REM will be
29*4882a593Smuzhiyun positive (will have the opposite sign of NUMER). These are
30*4882a593Smuzhiyun considered `wrong'. If both are NUM and DENOM are positive,
31*4882a593Smuzhiyun RESULT will always be positive. This all boils down to: if
32*4882a593Smuzhiyun NUMER >= 0, but REM < 0, we got the wrong answer. In that
33*4882a593Smuzhiyun case, to get the right answer, add 1 to QUOT and subtract
34*4882a593Smuzhiyun DENOM from REM. */
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun if (numer >= 0 && result.rem < 0)
37*4882a593Smuzhiyun {
38*4882a593Smuzhiyun ++result.quot;
39*4882a593Smuzhiyun result.rem -= denom;
40*4882a593Smuzhiyun }
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun return result;
43*4882a593Smuzhiyun }
44