include/linux/math64.h

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