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 <asm/div64.h>
7
8 #if BITS_PER_LONG == 64
9
10 #define div64_long(x, y) div64_s64((x), (y))
11 #define div64_ul(x, y) div64_u64((x), (y))
12
13 /**
14 * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
15 * @dividend: unsigned 64bit dividend
16 * @divisor: unsigned 32bit divisor
17 * @remainder: pointer to unsigned 32bit remainder
18 *
19 * Return: sets ``*remainder``, then returns dividend / divisor
20 *
21 * This is commonly provided by 32bit archs to provide an optimized 64bit
22 * divide.
23 */
div_u64_rem(u64 dividend,u32 divisor,u32 * remainder)24 static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
25 {
26 *remainder = dividend % divisor;
27 return dividend / divisor;
28 }
29
30 /**
31 * div_s64_rem - signed 64bit divide with 32bit divisor with remainder
32 * @dividend: signed 64bit dividend
33 * @divisor: signed 32bit divisor
34 * @remainder: pointer to signed 32bit remainder
35 *
36 * Return: sets ``*remainder``, then returns dividend / divisor
37 */
div_s64_rem(s64 dividend,s32 divisor,s32 * remainder)38 static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
39 {
40 *remainder = dividend % divisor;
41 return dividend / divisor;
42 }
43
44 /**
45 * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
46 * @dividend: unsigned 64bit dividend
47 * @divisor: unsigned 64bit divisor
48 * @remainder: pointer to unsigned 64bit remainder
49 *
50 * Return: sets ``*remainder``, then returns dividend / divisor
51 */
div64_u64_rem(u64 dividend,u64 divisor,u64 * remainder)52 static inline u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
53 {
54 *remainder = dividend % divisor;
55 return dividend / divisor;
56 }
57
58 /**
59 * div64_u64 - unsigned 64bit divide with 64bit divisor
60 * @dividend: unsigned 64bit dividend
61 * @divisor: unsigned 64bit divisor
62 *
63 * Return: dividend / divisor
64 */
div64_u64(u64 dividend,u64 divisor)65 static inline u64 div64_u64(u64 dividend, u64 divisor)
66 {
67 return dividend / divisor;
68 }
69
70 /**
71 * div64_s64 - signed 64bit divide with 64bit divisor
72 * @dividend: signed 64bit dividend
73 * @divisor: signed 64bit divisor
74 *
75 * Return: dividend / divisor
76 */
div64_s64(s64 dividend,s64 divisor)77 static inline s64 div64_s64(s64 dividend, s64 divisor)
78 {
79 return dividend / divisor;
80 }
81
82 #elif BITS_PER_LONG == 32
83
84 #define div64_long(x, y) div_s64((x), (y))
85 #define div64_ul(x, y) div_u64((x), (y))
86
87 #ifndef div_u64_rem
div_u64_rem(u64 dividend,u32 divisor,u32 * remainder)88 static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
89 {
90 *remainder = do_div(dividend, divisor);
91 return dividend;
92 }
93 #endif
94
95 #ifndef div_s64_rem
96 extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
97 #endif
98
99 #ifndef div64_u64_rem
100 extern u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder);
101 #endif
102
103 #ifndef div64_u64
104 extern u64 div64_u64(u64 dividend, u64 divisor);
105 #endif
106
107 #ifndef div64_s64
108 extern s64 div64_s64(s64 dividend, s64 divisor);
109 #endif
110
111 #endif /* BITS_PER_LONG */
112
113 /**
114 * div_u64 - unsigned 64bit divide with 32bit divisor
115 * @dividend: unsigned 64bit dividend
116 * @divisor: unsigned 32bit divisor
117 *
118 * This is the most common 64bit divide and should be used if possible,
119 * as many 32bit archs can optimize this variant better than a full 64bit
120 * divide.
121 */
122 #ifndef div_u64
div_u64(u64 dividend,u32 divisor)123 static inline u64 div_u64(u64 dividend, u32 divisor)
124 {
125 u32 remainder;
126 return div_u64_rem(dividend, divisor, &remainder);
127 }
128 #endif
129
130 /**
131 * div_s64 - signed 64bit divide with 32bit divisor
132 * @dividend: signed 64bit dividend
133 * @divisor: signed 32bit divisor
134 */
135 #ifndef div_s64
div_s64(s64 dividend,s32 divisor)136 static inline s64 div_s64(s64 dividend, s32 divisor)
137 {
138 s32 remainder;
139 return div_s64_rem(dividend, divisor, &remainder);
140 }
141 #endif
142
143 u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
144
145 static __always_inline u32
__iter_div_u64_rem(u64 dividend,u32 divisor,u64 * remainder)146 __iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
147 {
148 u32 ret = 0;
149
150 while (dividend >= divisor) {
151 /* The following asm() prevents the compiler from
152 optimising this loop into a modulo operation. */
153 asm("" : "+rm"(dividend));
154
155 dividend -= divisor;
156 ret++;
157 }
158
159 *remainder = dividend;
160
161 return ret;
162 }
163
164 #ifndef mul_u32_u32
165 /*
166 * Many a GCC version messes this up and generates a 64x64 mult :-(
167 */
mul_u32_u32(u32 a,u32 b)168 static inline u64 mul_u32_u32(u32 a, u32 b)
169 {
170 return (u64)a * b;
171 }
172 #endif
173
174 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
175
176 #ifndef mul_u64_u32_shr
mul_u64_u32_shr(u64 a,u32 mul,unsigned int shift)177 static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
178 {
179 return (u64)(((unsigned __int128)a * mul) >> shift);
180 }
181 #endif /* mul_u64_u32_shr */
182
183 #ifndef mul_u64_u64_shr
mul_u64_u64_shr(u64 a,u64 mul,unsigned int shift)184 static inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift)
185 {
186 return (u64)(((unsigned __int128)a * mul) >> shift);
187 }
188 #endif /* mul_u64_u64_shr */
189
190 #else
191
192 #ifndef mul_u64_u32_shr
mul_u64_u32_shr(u64 a,u32 mul,unsigned int shift)193 static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
194 {
195 u32 ah, al;
196 u64 ret;
197
198 al = a;
199 ah = a >> 32;
200
201 ret = mul_u32_u32(al, mul) >> shift;
202 if (ah)
203 ret += mul_u32_u32(ah, mul) << (32 - shift);
204
205 return ret;
206 }
207 #endif /* mul_u64_u32_shr */
208
209 #ifndef mul_u64_u64_shr
mul_u64_u64_shr(u64 a,u64 b,unsigned int shift)210 static inline u64 mul_u64_u64_shr(u64 a, u64 b, unsigned int shift)
211 {
212 union {
213 u64 ll;
214 struct {
215 #ifdef __BIG_ENDIAN
216 u32 high, low;
217 #else
218 u32 low, high;
219 #endif
220 } l;
221 } rl, rm, rn, rh, a0, b0;
222 u64 c;
223
224 a0.ll = a;
225 b0.ll = b;
226
227 rl.ll = mul_u32_u32(a0.l.low, b0.l.low);
228 rm.ll = mul_u32_u32(a0.l.low, b0.l.high);
229 rn.ll = mul_u32_u32(a0.l.high, b0.l.low);
230 rh.ll = mul_u32_u32(a0.l.high, b0.l.high);
231
232 /*
233 * Each of these lines computes a 64-bit intermediate result into "c",
234 * starting at bits 32-95. The low 32-bits go into the result of the
235 * multiplication, the high 32-bits are carried into the next step.
236 */
237 rl.l.high = c = (u64)rl.l.high + rm.l.low + rn.l.low;
238 rh.l.low = c = (c >> 32) + rm.l.high + rn.l.high + rh.l.low;
239 rh.l.high = (c >> 32) + rh.l.high;
240
241 /*
242 * The 128-bit result of the multiplication is in rl.ll and rh.ll,
243 * shift it right and throw away the high part of the result.
244 */
245 if (shift == 0)
246 return rl.ll;
247 if (shift < 64)
248 return (rl.ll >> shift) | (rh.ll << (64 - shift));
249 return rh.ll >> (shift & 63);
250 }
251 #endif /* mul_u64_u64_shr */
252
253 #endif
254
255 #ifndef mul_u64_u32_div
mul_u64_u32_div(u64 a,u32 mul,u32 divisor)256 static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor)
257 {
258 union {
259 u64 ll;
260 struct {
261 #ifdef __BIG_ENDIAN
262 u32 high, low;
263 #else
264 u32 low, high;
265 #endif
266 } l;
267 } u, rl, rh;
268
269 u.ll = a;
270 rl.ll = mul_u32_u32(u.l.low, mul);
271 rh.ll = mul_u32_u32(u.l.high, mul) + rl.l.high;
272
273 /* Bits 32-63 of the result will be in rh.l.low. */
274 rl.l.high = do_div(rh.ll, divisor);
275
276 /* Bits 0-31 of the result will be in rl.l.low. */
277 do_div(rl.ll, divisor);
278
279 rl.l.high = rh.l.low;
280 return rl.ll;
281 }
282 #endif /* mul_u64_u32_div */
283
284 #define DIV64_U64_ROUND_UP(ll, d) \
285 ({ u64 _tmp = (d); div64_u64((ll) + _tmp - 1, _tmp); })
286
287 #endif /* _LINUX_MATH64_H */
288