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 <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  */
  26 static 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  */
  40 static 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  */
  54 static 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  */
  67 static 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  */
  79 static 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
  90 static 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
  98 extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
  99 #endif
 100
 101 #ifndef div64_u64_rem
 102 extern u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder);
 103 #endif
 104
 105 #ifndef div64_u64
 106 extern u64 div64_u64(u64 dividend, u64 divisor);
 107 #endif
 108
 109 #ifndef div64_s64
 110 extern 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 #ifndef div_u64
 125 static inline u64 div_u64(u64 dividend, u32 divisor)
 126 {
 127         u32 remainder;
 128         return div_u64_rem(dividend, divisor, &remainder);
 129 }
 130 #endif
 131
 132 /**
 133  * div_s64 - signed 64bit divide with 32bit divisor
 134  * @dividend: signed 64bit dividend
 135  * @divisor: signed 32bit divisor
 136  */
 137 #ifndef div_s64
 138 static inline s64 div_s64(s64 dividend, s32 divisor)
 139 {
 140         s32 remainder;
 141         return div_s64_rem(dividend, divisor, &remainder);
 142 }
 143 #endif
 144
 145 u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
 146
 147 #ifndef mul_u32_u32
 148 /*
 149  * Many a GCC version messes this up and generates a 64x64 mult :-(
 150  */
 151 static inline u64 mul_u32_u32(u32 a, u32 b)
 152 {
 153         return (u64)a * b;
 154 }
 155 #endif
 156
 157 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
 158
 159 #ifndef mul_u64_u32_shr
 160 static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
 161 {
 162         return (u64)(((unsigned __int128)a * mul) >> shift);
 163 }
 164 #endif /* mul_u64_u32_shr */
 165
 166 #ifndef mul_u64_u64_shr
 167 static inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift)
 168 {
 169         return (u64)(((unsigned __int128)a * mul) >> shift);
 170 }
 171 #endif /* mul_u64_u64_shr */
 172
 173 #else
 174
 175 #ifndef mul_u64_u32_shr
 176 static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
 177 {
 178         u32 ah, al;
 179         u64 ret;
 180
 181         al = a;
 182         ah = a >> 32;
 183
 184         ret = mul_u32_u32(al, mul) >> shift;
 185         if (ah)
 186                 ret += mul_u32_u32(ah, mul) << (32 - shift);
 187
 188         return ret;
 189 }
 190 #endif /* mul_u64_u32_shr */
 191
 192 #ifndef mul_u64_u64_shr
 193 static inline u64 mul_u64_u64_shr(u64 a, u64 b, unsigned int shift)
 194 {
 195         union {
 196                 u64 ll;
 197                 struct {
 198 #ifdef __BIG_ENDIAN
 199                         u32 high, low;
 200 #else
 201                         u32 low, high;
 202 #endif
 203                 } l;
 204         } rl, rm, rn, rh, a0, b0;
 205         u64 c;
 206
 207         a0.ll = a;
 208         b0.ll = b;
 209
 210         rl.ll = mul_u32_u32(a0.l.low, b0.l.low);
 211         rm.ll = mul_u32_u32(a0.l.low, b0.l.high);
 212         rn.ll = mul_u32_u32(a0.l.high, b0.l.low);
 213         rh.ll = mul_u32_u32(a0.l.high, b0.l.high);
 214
 215         /*
 216          * Each of these lines computes a 64-bit intermediate result into "c",
 217          * starting at bits 32-95.  The low 32-bits go into the result of the
 218          * multiplication, the high 32-bits are carried into the next step.
 219          */
 220         rl.l.high = c = (u64)rl.l.high + rm.l.low + rn.l.low;
 221         rh.l.low = c = (c >> 32) + rm.l.high + rn.l.high + rh.l.low;
 222         rh.l.high = (c >> 32) + rh.l.high;
 223
 224         /*
 225          * The 128-bit result of the multiplication is in rl.ll and rh.ll,
 226          * shift it right and throw away the high part of the result.
 227          */
 228         if (shift == 0)
 229                 return rl.ll;
 230         if (shift < 64)
 231                 return (rl.ll >> shift) | (rh.ll << (64 - shift));
 232         return rh.ll >> (shift & 63);
 233 }
 234 #endif /* mul_u64_u64_shr */
 235
 236 #endif
 237
 238 #ifndef mul_s64_u64_shr
 239 static inline u64 mul_s64_u64_shr(s64 a, u64 b, unsigned int shift)
 240 {
 241         u64 ret;
 242
 243         /*
 244          * Extract the sign before the multiplication and put it back
 245          * afterwards if needed.
 246          */
 247         ret = mul_u64_u64_shr(abs(a), b, shift);
 248
 249         if (a < 0)
 250                 ret = -((s64) ret);
 251
 252         return ret;
 253 }
 254 #endif /* mul_s64_u64_shr */
 255
 256 #ifndef mul_u64_u32_div
 257 static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor)
 258 {
 259         union {
 260                 u64 ll;
 261                 struct {
 262 #ifdef __BIG_ENDIAN
 263                         u32 high, low;
 264 #else
 265                         u32 low, high;
 266 #endif
 267                 } l;
 268         } u, rl, rh;
 269
 270         u.ll = a;
 271         rl.ll = mul_u32_u32(u.l.low, mul);
 272         rh.ll = mul_u32_u32(u.l.high, mul) + rl.l.high;
 273
 274         /* Bits 32-63 of the result will be in rh.l.low. */
 275         rl.l.high = do_div(rh.ll, divisor);
 276
 277         /* Bits 0-31 of the result will be in rl.l.low. */
 278         do_div(rl.ll, divisor);
 279
 280         rl.l.high = rh.l.low;
 281         return rl.ll;
 282 }
 283 #endif /* mul_u64_u32_div */
 284
 285 u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div);
 286
 287 #define DIV64_U64_ROUND_UP(ll, d)       \
 288         ({ u64 _tmp = (d); div64_u64((ll) + _tmp - 1, _tmp); })
 289
 290 /**
 291  * DIV64_U64_ROUND_CLOSEST - unsigned 64bit divide with 64bit divisor rounded to nearest integer
 292  * @dividend: unsigned 64bit dividend
 293  * @divisor: unsigned 64bit divisor
 294  *
 295  * Divide unsigned 64bit dividend by unsigned 64bit divisor
 296  * and round to closest integer.
 297  *
 298  * Return: dividend / divisor rounded to nearest integer
 299  */
 300 #define DIV64_U64_ROUND_CLOSEST(dividend, divisor)      \
 301         ({ u64 _tmp = (divisor); div64_u64((dividend) + _tmp / 2, _tmp); })
 302
 303 /*
 304  * DIV_S64_ROUND_CLOSEST - signed 64bit divide with 32bit divisor rounded to nearest integer
 305  * @dividend: signed 64bit dividend
 306  * @divisor: signed 32bit divisor
 307  *
 308  * Divide signed 64bit dividend by signed 32bit divisor
 309  * and round to closest integer.
 310  *
 311  * Return: dividend / divisor rounded to nearest integer
 312  */
 313 #define DIV_S64_ROUND_CLOSEST(dividend, divisor)(       \
 314 {                                                       \
 315         s64 __x = (dividend);                           \
 316         s32 __d = (divisor);                            \
 317         ((__x > 0) == (__d > 0)) ?                      \
 318                 div_s64((__x + (__d / 2)), __d) :       \
 319                 div_s64((__x - (__d / 2)), __d);        \
 320 }                                                       \
 321 )
 322 #endif /* _LINUX_MATH64_H */