include/linux/math64.h

   1 #ifndef _LINUX_MATH64_H
   2 #define _LINUX_MATH64_H
   3
   4 #include <linux/types.h>
   5 #include <asm/div64.h>
   6
   7 #if BITS_PER_LONG == 64
   8
   9 #define div64_long(x, y) div64_s64((x), (y))
  10 #define div64_ul(x, y)   div64_u64((x), (y))
  11
  12 /**
  13  * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
  14  *
  15  * This is commonly provided by 32bit archs to provide an optimized 64bit
  16  * divide.
  17  */
  18 static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
  19 {
  20         *remainder = dividend % divisor;
  21         return dividend / divisor;
  22 }
  23
  24 /**
  25  * div_s64_rem - signed 64bit divide with 32bit divisor with remainder
  26  */
  27 static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
  28 {
  29         *remainder = dividend % divisor;
  30         return dividend / divisor;
  31 }
  32
  33 /**
  34  * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
  35  */
  36 static inline u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
  37 {
  38         *remainder = dividend % divisor;
  39         return dividend / divisor;
  40 }
  41
  42 /**
  43  * div64_u64 - unsigned 64bit divide with 64bit divisor
  44  */
  45 static inline u64 div64_u64(u64 dividend, u64 divisor)
  46 {
  47         return dividend / divisor;
  48 }
  49
  50 /**
  51  * div64_s64 - signed 64bit divide with 64bit divisor
  52  */
  53 static inline s64 div64_s64(s64 dividend, s64 divisor)
  54 {
  55         return dividend / divisor;
  56 }
  57
  58 #elif BITS_PER_LONG == 32
  59
  60 #define div64_long(x, y) div_s64((x), (y))
  61 #define div64_ul(x, y)   div_u64((x), (y))
  62
  63 #ifndef div_u64_rem
  64 static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
  65 {
  66         *remainder = do_div(dividend, divisor);
  67         return dividend;
  68 }
  69 #endif
  70
  71 #ifndef div_s64_rem
  72 extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
  73 #endif
  74
  75 #ifndef div64_u64_rem
  76 extern u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder);
  77 #endif
  78
  79 #ifndef div64_u64
  80 extern u64 div64_u64(u64 dividend, u64 divisor);
  81 #endif
  82
  83 #ifndef div64_s64
  84 extern s64 div64_s64(s64 dividend, s64 divisor);
  85 #endif
  86
  87 #endif /* BITS_PER_LONG */
  88
  89 /**
  90  * div_u64 - unsigned 64bit divide with 32bit divisor
  91  *
  92  * This is the most common 64bit divide and should be used if possible,
  93  * as many 32bit archs can optimize this variant better than a full 64bit
  94  * divide.
  95  */
  96 #ifndef div_u64
  97 static inline u64 div_u64(u64 dividend, u32 divisor)
  98 {
  99         u32 remainder;
 100         return div_u64_rem(dividend, divisor, &remainder);
 101 }
 102 #endif
 103
 104 /**
 105  * div_s64 - signed 64bit divide with 32bit divisor
 106  */
 107 #ifndef div_s64
 108 static inline s64 div_s64(s64 dividend, s32 divisor)
 109 {
 110         s32 remainder;
 111         return div_s64_rem(dividend, divisor, &remainder);
 112 }
 113 #endif
 114
 115 u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
 116
 117 static __always_inline u32
 118 __iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
 119 {
 120         u32 ret = 0;
 121
 122         while (dividend >= divisor) {
 123                 /* The following asm() prevents the compiler from
 124                    optimising this loop into a modulo operation.  */
 125                 asm("" : "+rm"(dividend));
 126
 127                 dividend -= divisor;
 128                 ret++;
 129         }
 130
 131         *remainder = dividend;
 132
 133         return ret;
 134 }
 135
 136 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
 137
 138 #ifndef mul_u64_u32_shr
 139 static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
 140 {
 141         return (u64)(((unsigned __int128)a * mul) >> shift);
 142 }
 143 #endif /* mul_u64_u32_shr */
 144
 145 #ifndef mul_u64_u64_shr
 146 static inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift)
 147 {
 148         return (u64)(((unsigned __int128)a * mul) >> shift);
 149 }
 150 #endif /* mul_u64_u64_shr */
 151
 152 #else
 153
 154 #ifndef mul_u64_u32_shr
 155 static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
 156 {
 157         u32 ah, al;
 158         u64 ret;
 159
 160         al = a;
 161         ah = a >> 32;
 162
 163         ret = ((u64)al * mul) >> shift;
 164         if (ah)
 165                 ret += ((u64)ah * mul) << (32 - shift);
 166
 167         return ret;
 168 }
 169 #endif /* mul_u64_u32_shr */
 170
 171 #ifndef mul_u64_u64_shr
 172 static inline u64 mul_u64_u64_shr(u64 a, u64 b, unsigned int shift)
 173 {
 174         union {
 175                 u64 ll;
 176                 struct {
 177 #ifdef __BIG_ENDIAN
 178                         u32 high, low;
 179 #else
 180                         u32 low, high;
 181 #endif
 182                 } l;
 183         } rl, rm, rn, rh, a0, b0;
 184         u64 c;
 185
 186         a0.ll = a;
 187         b0.ll = b;
 188
 189         rl.ll = (u64)a0.l.low * b0.l.low;
 190         rm.ll = (u64)a0.l.low * b0.l.high;
 191         rn.ll = (u64)a0.l.high * b0.l.low;
 192         rh.ll = (u64)a0.l.high * b0.l.high;
 193
 194         /*
 195          * Each of these lines computes a 64-bit intermediate result into "c",
 196          * starting at bits 32-95.  The low 32-bits go into the result of the
 197          * multiplication, the high 32-bits are carried into the next step.
 198          */
 199         rl.l.high = c = (u64)rl.l.high + rm.l.low + rn.l.low;
 200         rh.l.low = c = (c >> 32) + rm.l.high + rn.l.high + rh.l.low;
 201         rh.l.high = (c >> 32) + rh.l.high;
 202
 203         /*
 204          * The 128-bit result of the multiplication is in rl.ll and rh.ll,
 205          * shift it right and throw away the high part of the result.
 206          */
 207         if (shift == 0)
 208                 return rl.ll;
 209         if (shift < 64)
 210                 return (rl.ll >> shift) | (rh.ll << (64 - shift));
 211         return rh.ll >> (shift & 63);
 212 }
 213 #endif /* mul_u64_u64_shr */
 214
 215 #endif
 216
 217 #ifndef mul_u64_u32_div
 218 static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor)
 219 {
 220         union {
 221                 u64 ll;
 222                 struct {
 223 #ifdef __BIG_ENDIAN
 224                         u32 high, low;
 225 #else
 226                         u32 low, high;
 227 #endif
 228                 } l;
 229         } u, rl, rh;
 230
 231         u.ll = a;
 232         rl.ll = (u64)u.l.low * mul;
 233         rh.ll = (u64)u.l.high * mul + rl.l.high;
 234
 235         /* Bits 32-63 of the result will be in rh.l.low. */
 236         rl.l.high = do_div(rh.ll, divisor);
 237
 238         /* Bits 0-31 of the result will be in rl.l.low. */
 239         do_div(rl.ll, divisor);
 240
 241         rl.l.high = rh.l.low;
 242         return rl.ll;
 243 }
 244 #endif /* mul_u64_u32_div */
 245
 246 #endif /* _LINUX_MATH64_H */