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.
13  * The fast case for (n>>32 == 0) is handled inline by do_div().
16  * for some CPUs. __div64_32() can be overridden by linking arch-specific
28 /* Not needed on 64bit architectures */
29 #if BITS_PER_LONG == 32
37 	uint32_t high = rem >> 32;  in __div64_32()
39 	/* Reduce the thing a bit first */  in __div64_32()
43 		res = (uint64_t) high << 32;  in __div64_32()
44 		rem -= (uint64_t) (high*base) << 32;  in __div64_32()
54 			rem -= b;  in __div64_32()
73 		quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);  in div_s64_rem()
74 		*remainder = -*remainder;  in div_s64_rem()
76 			quotient = -quotient;  in div_s64_rem()
80 			quotient = -quotient;  in div_s64_rem()
88  * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
89  * @dividend:	64bit dividend
90  * @divisor:	64bit divisor
91  * @remainder:  64bit remainder
95  * is kept distinct to avoid slowing down the div64_u64 operation on 32bit
101 	u32 high = divisor >> 32;  in div64_u64_rem()
113 			quot--;  in div64_u64_rem()
115 		*remainder = dividend - quot * divisor;  in div64_u64_rem()
118 			*remainder -= divisor;  in div64_u64_rem()
128  * div64_u64 - unsigned 64bit divide with 64bit divisor
129  * @dividend:	64bit dividend
130  * @divisor:	64bit divisor
141 	u32 high = divisor >> 32;  in div64_u64()
151 			quot--;  in div64_u64()
152 		if ((dividend - quot * divisor) >= divisor)  in div64_u64()
169 	return (quot ^ t) - t;  in div64_s64()
174 #endif /* BITS_PER_LONG == 32 */
201 	u32 a_lo = a, a_hi = a >> 32, b_lo = b, b_hi = b >> 32;  in mul_u64_u64_div_u64()
205 	y = (u64)a_lo * b_hi + (u32)(x >> 32);  in mul_u64_u64_div_u64()
206 	z = (u64)a_hi * b_hi + (u32)(y >> 32);  in mul_u64_u64_div_u64()
208 	z += (u32)(y >> 32);  in mul_u64_u64_div_u64()
209 	x = (y << 32) + (u32)x;  in mul_u64_u64_div_u64()
217 #pragma GCC diagnostic ignored "-Wdiv-by-zero"  in mul_u64_u64_div_u64()
226 		u64 n = shift ? (n_lo >> shift) | (n_hi << (64 - shift)) : n_lo;  in mul_u64_u64_div_u64()
232 		 *   rem = (rem << shift) + (n_lo - (n << shift));  in mul_u64_u64_div_u64()
238 		return -1;  in mul_u64_u64_div_u64()
255 		p -= shift;  in mul_u64_u64_div_u64()
257 		n_hi |= n_lo >> (64 - shift);  in mul_u64_u64_div_u64()
260 			n_hi -= c;  in mul_u64_u64_div_u64()