include/linux/kernel.h

   1 #ifndef _LINUX_KERNEL_H
   2 #define _LINUX_KERNEL_H
   3
   4
   5 #include <linux/types.h>
   6
   7 #define USHRT_MAX       ((u16)(~0U))
   8 #define SHRT_MAX        ((s16)(USHRT_MAX>>1))
   9 #define SHRT_MIN        ((s16)(-SHRT_MAX - 1))
  10 #define INT_MAX         ((int)(~0U>>1))
  11 #define INT_MIN         (-INT_MAX - 1)
  12 #define UINT_MAX        (~0U)
  13 #define LONG_MAX        ((long)(~0UL>>1))
  14 #define LONG_MIN        (-LONG_MAX - 1)
  15 #define ULONG_MAX       (~0UL)
  16 #define LLONG_MAX       ((long long)(~0ULL>>1))
  17 #define LLONG_MIN       (-LLONG_MAX - 1)
  18 #define ULLONG_MAX      (~0ULL)
  19 #ifndef SIZE_MAX
  20 #define SIZE_MAX        (~(size_t)0)
  21 #endif
  22
  23 #define U8_MAX          ((u8)~0U)
  24 #define S8_MAX          ((s8)(U8_MAX>>1))
  25 #define S8_MIN          ((s8)(-S8_MAX - 1))
  26 #define U16_MAX         ((u16)~0U)
  27 #define S16_MAX         ((s16)(U16_MAX>>1))
  28 #define S16_MIN         ((s16)(-S16_MAX - 1))
  29 #define U32_MAX         ((u32)~0U)
  30 #define S32_MAX         ((s32)(U32_MAX>>1))
  31 #define S32_MIN         ((s32)(-S32_MAX - 1))
  32 #define U64_MAX         ((u64)~0ULL)
  33 #define S64_MAX         ((s64)(U64_MAX>>1))
  34 #define S64_MIN         ((s64)(-S64_MAX - 1))
  35
  36 #define STACK_MAGIC     0xdeadbeef
  37
  38 #define REPEAT_BYTE(x)  ((~0ul / 0xff) * (x))
  39
  40 #define ALIGN(x,a)              __ALIGN_MASK((x),(typeof(x))(a)-1)
  41 #define __ALIGN_MASK(x,mask)    (((x)+(mask))&~(mask))
  42 #define PTR_ALIGN(p, a)         ((typeof(p))ALIGN((unsigned long)(p), (a)))
  43 #define IS_ALIGNED(x, a)                (((x) & ((typeof(x))(a) - 1)) == 0)
  44
  45 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
  46
  47 /*
  48  * This looks more complex than it should be. But we need to
  49  * get the type for the ~ right in round_down (it needs to be
  50  * as wide as the result!), and we want to evaluate the macro
  51  * arguments just once each.
  52  */
  53 #define __round_mask(x, y) ((__typeof__(x))((y)-1))
  54 #define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
  55 #define round_down(x, y) ((x) & ~__round_mask(x, y))
  56
  57 #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
  58 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
  59
  60 #if BITS_PER_LONG == 32
  61 # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
  62 #else
  63 # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP(ll,d)
  64 #endif
  65
  66 /* The `const' in roundup() prevents gcc-3.3 from calling __divdi3 */
  67 #define roundup(x, y) (                                 \
  68 {                                                       \
  69         const typeof(y) __y = y;                        \
  70         (((x) + (__y - 1)) / __y) * __y;                \
  71 }                                                       \
  72 )
  73 #define rounddown(x, y) (                               \
  74 {                                                       \
  75         typeof(x) __x = (x);                            \
  76         __x - (__x % (y));                              \
  77 }                                                       \
  78 )
  79
  80 /*
  81  * Divide positive or negative dividend by positive divisor and round
  82  * to closest integer. Result is undefined for negative divisors and
  83  * for negative dividends if the divisor variable type is unsigned.
  84  */
  85 #define DIV_ROUND_CLOSEST(x, divisor)(                  \
  86 {                                                       \
  87         typeof(x) __x = x;                              \
  88         typeof(divisor) __d = divisor;                  \
  89         (((typeof(x))-1) > 0 ||                         \
  90          ((typeof(divisor))-1) > 0 || (__x) > 0) ?      \
  91                 (((__x) + ((__d) / 2)) / (__d)) :       \
  92                 (((__x) - ((__d) / 2)) / (__d));        \
  93 }                                                       \
  94 )
  95
  96 /*
  97  * Multiplies an integer by a fraction, while avoiding unnecessary
  98  * overflow or loss of precision.
  99  */
 100 #define mult_frac(x, numer, denom)(                     \
 101 {                                                       \
 102         typeof(x) quot = (x) / (denom);                 \
 103         typeof(x) rem  = (x) % (denom);                 \
 104         (quot * (numer)) + ((rem * (numer)) / (denom)); \
 105 }                                                       \
 106 )
 107
 108 /**
 109  * upper_32_bits - return bits 32-63 of a number
 110  * @n: the number we're accessing
 111  *
 112  * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
 113  * the "right shift count >= width of type" warning when that quantity is
 114  * 32-bits.
 115  */
 116 #define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
 117
 118 /**
 119  * lower_32_bits - return bits 0-31 of a number
 120  * @n: the number we're accessing
 121  */
 122 #define lower_32_bits(n) ((u32)(n))
 123
 124 /*
 125  * abs() handles unsigned and signed longs, ints, shorts and chars.  For all
 126  * input types abs() returns a signed long.
 127  * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64()
 128  * for those.
 129  */
 130 #define abs(x) ({                                               \
 131                 long ret;                                       \
 132                 if (sizeof(x) == sizeof(long)) {                \
 133                         long __x = (x);                         \
 134                         ret = (__x < 0) ? -__x : __x;           \
 135                 } else {                                        \
 136                         int __x = (x);                          \
 137                         ret = (__x < 0) ? -__x : __x;           \
 138                 }                                               \
 139                 ret;                                            \
 140         })
 141
 142 #define abs64(x) ({                             \
 143                 s64 __x = (x);                  \
 144                 (__x < 0) ? -__x : __x;         \
 145         })
 146
 147 /*
 148  * min()/max()/clamp() macros that also do
 149  * strict type-checking.. See the
 150  * "unnecessary" pointer comparison.
 151  */
 152 #define min(x, y) ({                            \
 153         typeof(x) _min1 = (x);                  \
 154         typeof(y) _min2 = (y);                  \
 155         (void) (&_min1 == &_min2);              \
 156         _min1 < _min2 ? _min1 : _min2; })
 157
 158 #define max(x, y) ({                            \
 159         typeof(x) _max1 = (x);                  \
 160         typeof(y) _max2 = (y);                  \
 161         (void) (&_max1 == &_max2);              \
 162         _max1 > _max2 ? _max1 : _max2; })
 163
 164 #define min3(x, y, z) min((typeof(x))min(x, y), z)
 165 #define max3(x, y, z) max((typeof(x))max(x, y), z)
 166
 167 /**
 168  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
 169  * @x: value1
 170  * @y: value2
 171  */
 172 #define min_not_zero(x, y) ({                   \
 173         typeof(x) __x = (x);                    \
 174         typeof(y) __y = (y);                    \
 175         __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
 176
 177 /**
 178  * clamp - return a value clamped to a given range with strict typechecking
 179  * @val: current value
 180  * @lo: lowest allowable value
 181  * @hi: highest allowable value
 182  *
 183  * This macro does strict typechecking of lo/hi to make sure they are of the
 184  * same type as val.  See the unnecessary pointer comparisons.
 185  */
 186 #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
 187
 188 /*
 189  * ..and if you can't take the strict
 190  * types, you can specify one yourself.
 191  *
 192  * Or not use min/max/clamp at all, of course.
 193  */
 194 #define min_t(type, x, y) ({                    \
 195         type __min1 = (x);                      \
 196         type __min2 = (y);                      \
 197         __min1 < __min2 ? __min1: __min2; })
 198
 199 #define max_t(type, x, y) ({                    \
 200         type __max1 = (x);                      \
 201         type __max2 = (y);                      \
 202         __max1 > __max2 ? __max1: __max2; })
 203
 204 /**
 205  * clamp_t - return a value clamped to a given range using a given type
 206  * @type: the type of variable to use
 207  * @val: current value
 208  * @lo: minimum allowable value
 209  * @hi: maximum allowable value
 210  *
 211  * This macro does no typechecking and uses temporary variables of type
 212  * 'type' to make all the comparisons.
 213  */
 214 #define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
 215
 216 /**
 217  * clamp_val - return a value clamped to a given range using val's type
 218  * @val: current value
 219  * @lo: minimum allowable value
 220  * @hi: maximum allowable value
 221  *
 222  * This macro does no typechecking and uses temporary variables of whatever
 223  * type the input argument 'val' is.  This is useful when val is an unsigned
 224  * type and min and max are literals that will otherwise be assigned a signed
 225  * integer type.
 226  */
 227 #define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
 228
 229
 230 /*
 231  * swap - swap value of @a and @b
 232  */
 233 #define swap(a, b) \
 234         do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 235
 236 /**
 237  * container_of - cast a member of a structure out to the containing structure
 238  * @ptr:        the pointer to the member.
 239  * @type:       the type of the container struct this is embedded in.
 240  * @member:     the name of the member within the struct.
 241  *
 242  */
 243 #define container_of(ptr, type, member) ({                      \
 244         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 245         (type *)( (char *)__mptr - offsetof(type,member) );})
 246
 247 #endif