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   1 /* MN10300 64-bit division
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11 #ifndef _ASM_DIV64
  12 #define _ASM_DIV64
  13
  14 #include <linux/types.h>
  15
  16 extern void ____unhandled_size_in_do_div___(void);
  17
  18 /*
  19  * divide n by base, leaving the result in n and returning the remainder
  20  * - we can do this quite efficiently on the MN10300 by cascading the divides
  21  *   through the MDR register
  22  */
  23 #define do_div(n, base)                                                 \
  24 ({                                                                      \
  25         unsigned __rem = 0;                                             \
  26         if (sizeof(n) <= 4) {                                           \
  27                 asm("mov        %1,mdr  \n"                             \
  28                     "divu       %2,%0   \n"                             \
  29                     "mov        mdr,%1  \n"                             \
  30                     : "+r"(n), "=d"(__rem)                              \
  31                     : "r"(base), "1"(__rem)                             \
  32                     : "cc"                                              \
  33                     );                                                  \
  34         } else if (sizeof(n) <= 8) {                                    \
  35                 union {                                                 \
  36                         unsigned long long l;                           \
  37                         u32 w[2];                                       \
  38                 } __quot;                                               \
  39                 __quot.l = n;                                           \
  40                 asm("mov        %0,mdr  \n"     /* MDR = 0 */           \
  41                     "divu       %3,%1   \n"                             \
  42                     /* __quot.MSL = __div.MSL / base, */                \
  43                     /* MDR = MDR:__div.MSL % base */                    \
  44                     "divu       %3,%2   \n"                             \
  45                     /* __quot.LSL = MDR:__div.LSL / base, */            \
  46                     /* MDR = MDR:__div.LSL % base */                    \
  47                     "mov        mdr,%0  \n"                             \
  48                     : "=d"(__rem), "=r"(__quot.w[1]), "=r"(__quot.w[0]) \
  49                     : "r"(base), "0"(__rem), "1"(__quot.w[1]),          \
  50                       "2"(__quot.w[0])                                  \
  51                     : "cc"                                              \
  52                     );                                                  \
  53                 n = __quot.l;                                           \
  54         } else {                                                        \
  55                 ____unhandled_size_in_do_div___();                      \
  56         }                                                               \
  57         __rem;                                                          \
  58 })
  59
  60 /*
  61  * do an unsigned 32-bit multiply and divide with intermediate 64-bit product
  62  * so as not to lose accuracy
  63  * - we use the MDR register to hold the MSW of the product
  64  */
  65 static inline __attribute__((const))
  66 unsigned __muldiv64u(unsigned val, unsigned mult, unsigned div)
  67 {
  68         unsigned result;
  69
  70         asm("mulu       %2,%0   \n"     /* MDR:val = val*mult */
  71             "divu       %3,%0   \n"     /* val = MDR:val/div;
  72                                          * MDR = MDR:val%div */
  73             : "=r"(result)
  74             : "0"(val), "ir"(mult), "r"(div)
  75             );
  76
  77         return result;
  78 }
  79
  80 /*
  81  * do a signed 32-bit multiply and divide with intermediate 64-bit product so
  82  * as not to lose accuracy
  83  * - we use the MDR register to hold the MSW of the product
  84  */
  85 static inline __attribute__((const))
  86 signed __muldiv64s(signed val, signed mult, signed div)
  87 {
  88         signed result;
  89
  90         asm("mul        %2,%0   \n"     /* MDR:val = val*mult */
  91             "div        %3,%0   \n"     /* val = MDR:val/div;
  92                                          * MDR = MDR:val%div */
  93             : "=r"(result)
  94             : "0"(val), "ir"(mult), "r"(div)
  95             );
  96
  97         return result;
  98 }
  99
 100 #endif /* _ASM_DIV64 */