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