1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_MATH64_H
3#define _LINUX_MATH64_H
4
5#include <linux/types.h>
6#include <linux/math.h>
7#include <vdso/math64.h>
8#include <asm/div64.h>
9
10#if BITS_PER_LONG == 64
11
12#define div64_long(x, y) div64_s64((x), (y))
13#define div64_ul(x, y) div64_u64((x), (y))
14
15/**
16 * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
17 * @dividend: unsigned 64bit dividend
18 * @divisor: unsigned 32bit divisor
19 * @remainder: pointer to unsigned 32bit remainder
20 *
21 * Return: sets ``*remainder``, then returns dividend / divisor
22 *
23 * This is commonly provided by 32bit archs to provide an optimized 64bit
24 * divide.
25 */
26static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
27{
28 *remainder = dividend % divisor;
29 return dividend / divisor;
30}
31
32/**
33 * div_s64_rem - signed 64bit divide with 32bit divisor with remainder
34 * @dividend: signed 64bit dividend
35 * @divisor: signed 32bit divisor
36 * @remainder: pointer to signed 32bit remainder
37 *
38 * Return: sets ``*remainder``, then returns dividend / divisor
39 */
40static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
41{
42 *remainder = dividend % divisor;
43 return dividend / divisor;
44}
45
46/**
47 * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
48 * @dividend: unsigned 64bit dividend
49 * @divisor: unsigned 64bit divisor
50 * @remainder: pointer to unsigned 64bit remainder
51 *
52 * Return: sets ``*remainder``, then returns dividend / divisor
53 */
54static inline u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
55{
56 *remainder = dividend % divisor;
57 return dividend / divisor;
58}
59
60/**
61 * div64_u64 - unsigned 64bit divide with 64bit divisor
62 * @dividend: unsigned 64bit dividend
63 * @divisor: unsigned 64bit divisor
64 *
65 * Return: dividend / divisor
66 */
67static inline u64 div64_u64(u64 dividend, u64 divisor)
68{
69 return dividend / divisor;
70}
71
72/**
73 * div64_s64 - signed 64bit divide with 64bit divisor
74 * @dividend: signed 64bit dividend
75 * @divisor: signed 64bit divisor
76 *
77 * Return: dividend / divisor
78 */
79static inline s64 div64_s64(s64 dividend, s64 divisor)
80{
81 return dividend / divisor;
82}
83
84#elif BITS_PER_LONG == 32
85
86#define div64_long(x, y) div_s64((x), (y))
87#define div64_ul(x, y) div_u64((x), (y))
88
89#ifndef div_u64_rem
90static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
91{
92 *remainder = do_div(dividend, divisor);
93 return dividend;
94}
95#endif
96
97#ifndef div_s64_rem
98extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
99#endif
100
101#ifndef div64_u64_rem
102extern u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder);
103#endif
104
105#ifndef div64_u64
106extern u64 div64_u64(u64 dividend, u64 divisor);
107#endif
108
109#ifndef div64_s64
110extern s64 div64_s64(s64 dividend, s64 divisor);
111#endif
112
113#endif /* BITS_PER_LONG */
114
115/**
116 * div_u64 - unsigned 64bit divide with 32bit divisor
117 * @dividend: unsigned 64bit dividend
118 * @divisor: unsigned 32bit divisor
119 *
120 * This is the most common 64bit divide and should be used if possible,
121 * as many 32bit archs can optimize this variant better than a full 64bit
122 * divide.
123 *
124 * Return: dividend / divisor
125 */
126#ifndef div_u64
127static inline u64 div_u64(u64 dividend, u32 divisor)
128{
129 u32 remainder;
130 return div_u64_rem(dividend, divisor, remainder: &remainder);
131}
132#endif
133
134/**
135 * div_s64 - signed 64bit divide with 32bit divisor
136 * @dividend: signed 64bit dividend
137 * @divisor: signed 32bit divisor
138 *
139 * Return: dividend / divisor
140 */
141#ifndef div_s64
142static inline s64 div_s64(s64 dividend, s32 divisor)
143{
144 s32 remainder;
145 return div_s64_rem(dividend, divisor, remainder: &remainder);
146}
147#endif
148
149u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
150
151#ifndef mul_u32_u32
152/*
153 * Many a GCC version messes this up and generates a 64x64 mult :-(
154 */
155static inline u64 mul_u32_u32(u32 a, u32 b)
156{
157 return (u64)a * b;
158}
159#endif
160
161#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
162
163#ifndef mul_u64_u32_shr
164static __always_inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
165{
166 return (u64)(((unsigned __int128)a * mul) >> shift);
167}
168#endif /* mul_u64_u32_shr */
169
170#ifndef mul_u64_u64_shr
171static __always_inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift)
172{
173 return (u64)(((unsigned __int128)a * mul) >> shift);
174}
175#endif /* mul_u64_u64_shr */
176
177#else
178
179#ifndef mul_u64_u32_shr
180static __always_inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
181{
182 u32 ah, al;
183 u64 ret;
184
185 al = a;
186 ah = a >> 32;
187
188 ret = mul_u32_u32(al, mul) >> shift;
189 if (ah)
190 ret += mul_u32_u32(ah, mul) << (32 - shift);
191
192 return ret;
193}
194#endif /* mul_u64_u32_shr */
195
196#ifndef mul_u64_u64_shr
197static inline u64 mul_u64_u64_shr(u64 a, u64 b, unsigned int shift)
198{
199 union {
200 u64 ll;
201 struct {
202#ifdef __BIG_ENDIAN
203 u32 high, low;
204#else
205 u32 low, high;
206#endif
207 } l;
208 } rl, rm, rn, rh, a0, b0;
209 u64 c;
210
211 a0.ll = a;
212 b0.ll = b;
213
214 rl.ll = mul_u32_u32(a0.l.low, b0.l.low);
215 rm.ll = mul_u32_u32(a0.l.low, b0.l.high);
216 rn.ll = mul_u32_u32(a0.l.high, b0.l.low);
217 rh.ll = mul_u32_u32(a0.l.high, b0.l.high);
218
219 /*
220 * Each of these lines computes a 64-bit intermediate result into "c",
221 * starting at bits 32-95. The low 32-bits go into the result of the
222 * multiplication, the high 32-bits are carried into the next step.
223 */
224 rl.l.high = c = (u64)rl.l.high + rm.l.low + rn.l.low;
225 rh.l.low = c = (c >> 32) + rm.l.high + rn.l.high + rh.l.low;
226 rh.l.high = (c >> 32) + rh.l.high;
227
228 /*
229 * The 128-bit result of the multiplication is in rl.ll and rh.ll,
230 * shift it right and throw away the high part of the result.
231 */
232 if (shift == 0)
233 return rl.ll;
234 if (shift < 64)
235 return (rl.ll >> shift) | (rh.ll << (64 - shift));
236 return rh.ll >> (shift & 63);
237}
238#endif /* mul_u64_u64_shr */
239
240#endif
241
242#ifndef mul_s64_u64_shr
243static inline u64 mul_s64_u64_shr(s64 a, u64 b, unsigned int shift)
244{
245 u64 ret;
246
247 /*
248 * Extract the sign before the multiplication and put it back
249 * afterwards if needed.
250 */
251 ret = mul_u64_u64_shr(abs(a), mul: b, shift);
252
253 if (a < 0)
254 ret = -((s64) ret);
255
256 return ret;
257}
258#endif /* mul_s64_u64_shr */
259
260#ifndef mul_u64_u32_div
261static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor)
262{
263 union {
264 u64 ll;
265 struct {
266#ifdef __BIG_ENDIAN
267 u32 high, low;
268#else
269 u32 low, high;
270#endif
271 } l;
272 } u, rl, rh;
273
274 u.ll = a;
275 rl.ll = mul_u32_u32(u.l.low, mul);
276 rh.ll = mul_u32_u32(u.l.high, mul) + rl.l.high;
277
278 /* Bits 32-63 of the result will be in rh.l.low. */
279 rl.l.high = do_div(rh.ll, divisor);
280
281 /* Bits 0-31 of the result will be in rl.l.low. */
282 do_div(rl.ll, divisor);
283
284 rl.l.high = rh.l.low;
285 return rl.ll;
286}
287#endif /* mul_u64_u32_div */
288
289u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div);
290
291/**
292 * DIV64_U64_ROUND_UP - unsigned 64bit divide with 64bit divisor rounded up
293 * @ll: unsigned 64bit dividend
294 * @d: unsigned 64bit divisor
295 *
296 * Divide unsigned 64bit dividend by unsigned 64bit divisor
297 * and round up.
298 *
299 * Return: dividend / divisor rounded up
300 */
301#define DIV64_U64_ROUND_UP(ll, d) \
302 ({ u64 _tmp = (d); div64_u64((ll) + _tmp - 1, _tmp); })
303
304/**
305 * DIV64_U64_ROUND_CLOSEST - unsigned 64bit divide with 64bit divisor rounded to nearest integer
306 * @dividend: unsigned 64bit dividend
307 * @divisor: unsigned 64bit divisor
308 *
309 * Divide unsigned 64bit dividend by unsigned 64bit divisor
310 * and round to closest integer.
311 *
312 * Return: dividend / divisor rounded to nearest integer
313 */
314#define DIV64_U64_ROUND_CLOSEST(dividend, divisor) \
315 ({ u64 _tmp = (divisor); div64_u64((dividend) + _tmp / 2, _tmp); })
316
317/**
318 * DIV_U64_ROUND_CLOSEST - unsigned 64bit divide with 32bit divisor rounded to nearest integer
319 * @dividend: unsigned 64bit dividend
320 * @divisor: unsigned 32bit divisor
321 *
322 * Divide unsigned 64bit dividend by unsigned 32bit divisor
323 * and round to closest integer.
324 *
325 * Return: dividend / divisor rounded to nearest integer
326 */
327#define DIV_U64_ROUND_CLOSEST(dividend, divisor) \
328 ({ u32 _tmp = (divisor); div_u64((u64)(dividend) + _tmp / 2, _tmp); })
329
330/**
331 * DIV_S64_ROUND_CLOSEST - signed 64bit divide with 32bit divisor rounded to nearest integer
332 * @dividend: signed 64bit dividend
333 * @divisor: signed 32bit divisor
334 *
335 * Divide signed 64bit dividend by signed 32bit divisor
336 * and round to closest integer.
337 *
338 * Return: dividend / divisor rounded to nearest integer
339 */
340#define DIV_S64_ROUND_CLOSEST(dividend, divisor)( \
341{ \
342 s64 __x = (dividend); \
343 s32 __d = (divisor); \
344 ((__x > 0) == (__d > 0)) ? \
345 div_s64((__x + (__d / 2)), __d) : \
346 div_s64((__x - (__d / 2)), __d); \
347} \
348)
349#endif /* _LINUX_MATH64_H */
350

source code of linux/include/linux/math64.h