lib/math/div64.c

1 // SPDX-License-Identifier: GPL-2.0
5  * Based on former do_div() implementation from asm-parisc/div64.h:
6  *	Copyright (C) 1999 Hewlett-Packard Co
7  *	Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
10  * Generic C version of 64bit/32bit division and modulo, with
11  * 64bit result and 32bit remainder.
16  * for some CPUs. __div64_32() can be overridden by linking arch-specific
27 /* Not needed on 64bit architectures */
38 	/* Reduce the thing a bit first */  in __div64_32()
43 		rem -= (uint64_t) (high*base) << 32;  in __div64_32()
53 			rem -= b;  in __div64_32()
72 		quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);  in div_s64_rem()
73 		*remainder = -*remainder;  in div_s64_rem()
75 			quotient = -quotient;  in div_s64_rem()
79 			quotient = -quotient;  in div_s64_rem()
87  * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
88  * @dividend:	64bit dividend
89  * @divisor:	64bit divisor
90  * @remainder:  64bit remainder
94  * is kept distinct to avoid slowing down the div64_u64 operation on 32bit
112 			quot--;  in div64_u64_rem()
114 		*remainder = dividend - quot * divisor;  in div64_u64_rem()
117 			*remainder -= divisor;  in div64_u64_rem()
127  * div64_u64 - unsigned 64bit divide with 64bit divisor
128  * @dividend:	64bit dividend
129  * @divisor:	64bit divisor
150 			quot--;  in div64_u64()
151 		if ((dividend - quot * divisor) >= divisor)  in div64_u64()
168 	return (quot ^ t) - t;  in div64_s64()
212 		shift = ilog2(a) + ilog2(b) - 62;  in mul_u64_u64_div_u64()