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 #ifndef mul_u32_u32
 137 /*
 138  * Many a GCC version messes this up and generates a 64x64 mult :-(
 139  */
 140 static inline u64 mul_u32_u32(u32 a, u32 b)
 141 {
 142         return (u64)a * b;
 143 }
 144 #endif
 145
 146 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
 147
 148 #ifndef mul_u64_u32_shr
 149 static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
 150 {
 151         return (u64)(((unsigned __int128)a * mul) >> shift);
 152 }
 153 #endif /* mul_u64_u32_shr */
 154
 155 #ifndef mul_u64_u64_shr
 156 static inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift)
 157 {
 158         return (u64)(((unsigned __int128)a * mul) >> shift);
 159 }
 160 #endif /* mul_u64_u64_shr */
 161
 162 #else
 163
 164 #ifndef mul_u64_u32_shr
 165 static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
 166 {
 167         u32 ah, al;
 168         u64 ret;
 169
 170         al = a;
 171         ah = a >> 32;
 172
 173         ret = mul_u32_u32(al, mul) >> shift;
 174         if (ah)
 175                 ret += mul_u32_u32(ah, mul) << (32 - shift);
 176
 177         return ret;
 178 }
 179 #endif /* mul_u64_u32_shr */
 180
 181 #ifndef mul_u64_u64_shr
 182 static inline u64 mul_u64_u64_shr(u64 a, u64 b, unsigned int shift)
 183 {
 184         union {
 185                 u64 ll;
 186                 struct {
 187 #ifdef __BIG_ENDIAN
 188                         u32 high, low;
 189 #else
 190                         u32 low, high;
 191 #endif
 192                 } l;
 193         } rl, rm, rn, rh, a0, b0;
 194         u64 c;
 195
 196         a0.ll = a;
 197         b0.ll = b;
 198
 199         rl.ll = mul_u32_u32(a0.l.low, b0.l.low);
 200         rm.ll = mul_u32_u32(a0.l.low, b0.l.high);
 201         rn.ll = mul_u32_u32(a0.l.high, b0.l.low);
 202         rh.ll = mul_u32_u32(a0.l.high, b0.l.high);
 203
 204         /*
 205          * Each of these lines computes a 64-bit intermediate result into "c",
 206          * starting at bits 32-95.  The low 32-bits go into the result of the
 207          * multiplication, the high 32-bits are carried into the next step.
 208          */
 209         rl.l.high = c = (u64)rl.l.high + rm.l.low + rn.l.low;
 210         rh.l.low = c = (c >> 32) + rm.l.high + rn.l.high + rh.l.low;
 211         rh.l.high = (c >> 32) + rh.l.high;
 212
 213         /*
 214          * The 128-bit result of the multiplication is in rl.ll and rh.ll,
 215          * shift it right and throw away the high part of the result.
 216          */
 217         if (shift == 0)
 218                 return rl.ll;
 219         if (shift < 64)
 220                 return (rl.ll >> shift) | (rh.ll << (64 - shift));
 221         return rh.ll >> (shift & 63);
 222 }
 223 #endif /* mul_u64_u64_shr */
 224
 225 #endif
 226
 227 #ifndef mul_u64_u32_div
 228 static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor)
 229 {
 230         union {
 231                 u64 ll;
 232                 struct {
 233 #ifdef __BIG_ENDIAN
 234                         u32 high, low;
 235 #else
 236                         u32 low, high;
 237 #endif
 238                 } l;
 239         } u, rl, rh;
 240
 241         u.ll = a;
 242         rl.ll = mul_u32_u32(u.l.low, mul);
 243         rh.ll = mul_u32_u32(u.l.high, mul) + rl.l.high;
 244
 245         /* Bits 32-63 of the result will be in rh.l.low. */
 246         rl.l.high = do_div(rh.ll, divisor);
 247
 248         /* Bits 0-31 of the result will be in rl.l.low. */
 249         do_div(rl.ll, divisor);
 250
 251         rl.l.high = rh.l.low;
 252         return rl.ll;
 253 }
 254 #endif /* mul_u64_u32_div */
 255
 256 #endif /* _LINUX_MATH64_H */