Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0 */
       2             : #ifndef _ASM_X86_DIV64_H
       3             : #define _ASM_X86_DIV64_H
       4             : 
       5             : #ifdef CONFIG_X86_32
       6             : 
       7             : #include <linux/types.h>
       8             : #include <linux/log2.h>
       9             : 
      10             : /*
      11             :  * do_div() is NOT a C function. It wants to return
      12             :  * two values (the quotient and the remainder), but
      13             :  * since that doesn't work very well in C, what it
      14             :  * does is:
      15             :  *
      16             :  * - modifies the 64-bit dividend _in_place_
      17             :  * - returns the 32-bit remainder
      18             :  *
      19             :  * This ends up being the most efficient "calling
      20             :  * convention" on x86.
      21             :  */
      22             : #define do_div(n, base)                                         \
      23             : ({                                                              \
      24             :         unsigned long __upper, __low, __high, __mod, __base;    \
      25             :         __base = (base);                                        \
      26             :         if (__builtin_constant_p(__base) && is_power_of_2(__base)) { \
      27             :                 __mod = n & (__base - 1);                   \
      28             :                 n >>= ilog2(__base);                              \
      29             :         } else {                                                \
      30             :                 asm("" : "=a" (__low), "=d" (__high) : "A" (n));\
      31             :                 __upper = __high;                               \
      32             :                 if (__high) {                                   \
      33             :                         __upper = __high % (__base);            \
      34             :                         __high = __high / (__base);             \
      35             :                 }                                               \
      36             :                 asm("divl %2" : "=a" (__low), "=d" (__mod)        \
      37             :                         : "rm" (__base), "0" (__low), "1" (__upper));     \
      38             :                 asm("" : "=A" (n) : "a" (__low), "d" (__high)); \
      39             :         }                                                       \
      40             :         __mod;                                                  \
      41             : })
      42             : 
      43             : static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
      44             : {
      45             :         union {
      46             :                 u64 v64;
      47             :                 u32 v32[2];
      48             :         } d = { dividend };
      49             :         u32 upper;
      50             : 
      51             :         upper = d.v32[1];
      52             :         d.v32[1] = 0;
      53             :         if (upper >= divisor) {
      54             :                 d.v32[1] = upper / divisor;
      55             :                 upper %= divisor;
      56             :         }
      57             :         asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
      58             :                 "rm" (divisor), "0" (d.v32[0]), "1" (upper));
      59             :         return d.v64;
      60             : }
      61             : #define div_u64_rem     div_u64_rem
      62             : 
      63             : static inline u64 mul_u32_u32(u32 a, u32 b)
      64             : {
      65             :         u32 high, low;
      66             : 
      67             :         asm ("mull %[b]" : "=a" (low), "=d" (high)
      68             :                          : [a] "a" (a), [b] "rm" (b) );
      69             : 
      70             :         return low | ((u64)high) << 32;
      71             : }
      72             : #define mul_u32_u32 mul_u32_u32
      73             : 
      74             : #else
      75             : # include <asm-generic/div64.h>
      76             : 
      77             : /*
      78             :  * Will generate an #DE when the result doesn't fit u64, could fix with an
      79             :  * __ex_table[] entry when it becomes an issue.
      80             :  */
      81         205 : static inline u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div)
      82             : {
      83         205 :         u64 q;
      84             : 
      85         205 :         asm ("mulq %2; divq %3" : "=a" (q)
      86             :                                 : "a" (a), "rm" (mul), "rm" (div)
      87             :                                 : "rdx");
      88             : 
      89         205 :         return q;
      90             : }
      91             : #define mul_u64_u64_div_u64 mul_u64_u64_div_u64
      92             : 
      93           0 : static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 div)
      94             : {
      95           0 :         return mul_u64_u64_div_u64(a, mul, div);
      96             : }
      97             : #define mul_u64_u32_div mul_u64_u32_div
      98             : 
      99             : #endif /* CONFIG_X86_32 */
     100             : 
     101             : #endif /* _ASM_X86_DIV64_H */