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5270 | serge | 1 | #ifndef _ASM_X86_DIV64_H |
2 | #define _ASM_X86_DIV64_H |
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3 | |||
4 | #ifdef CONFIG_X86_32 |
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5 | |||
6 | #include |
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7 | #include |
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8 | |||
9 | /* |
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10 | * do_div() is NOT a C function. It wants to return |
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11 | * two values (the quotient and the remainder), but |
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12 | * since that doesn't work very well in C, what it |
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13 | * does is: |
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14 | * |
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15 | * - modifies the 64-bit dividend _in_place_ |
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16 | * - returns the 32-bit remainder |
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17 | * |
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18 | * This ends up being the most efficient "calling |
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19 | * convention" on x86. |
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20 | */ |
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21 | #define do_div(n, base) \ |
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22 | ({ \ |
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23 | unsigned long __upper, __low, __high, __mod, __base; \ |
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24 | __base = (base); \ |
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25 | if (__builtin_constant_p(__base) && is_power_of_2(__base)) { \ |
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26 | __mod = n & (__base - 1); \ |
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27 | n >>= ilog2(__base); \ |
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28 | } else { \ |
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29 | asm("" : "=a" (__low), "=d" (__high) : "A" (n));\ |
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30 | __upper = __high; \ |
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31 | if (__high) { \ |
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32 | __upper = __high % (__base); \ |
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33 | __high = __high / (__base); \ |
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34 | } \ |
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35 | asm("divl %2" : "=a" (__low), "=d" (__mod) \ |
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36 | : "rm" (__base), "0" (__low), "1" (__upper)); \ |
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37 | asm("" : "=A" (n) : "a" (__low), "d" (__high)); \ |
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38 | } \ |
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39 | __mod; \ |
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40 | }) |
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41 | |||
42 | static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) |
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43 | { |
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44 | union { |
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45 | u64 v64; |
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46 | u32 v32[2]; |
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47 | } d = { dividend }; |
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48 | u32 upper; |
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49 | |||
50 | upper = d.v32[1]; |
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51 | d.v32[1] = 0; |
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52 | if (upper >= divisor) { |
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53 | d.v32[1] = upper / divisor; |
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54 | upper %= divisor; |
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55 | } |
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56 | asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) : |
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57 | "rm" (divisor), "0" (d.v32[0]), "1" (upper)); |
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58 | return d.v64; |
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59 | } |
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60 | #define div_u64_rem div_u64_rem |
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61 | |||
62 | #else |
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63 | # include |
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64 | #endif /* CONFIG_X86_32 */ |
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65 | |||
66 | #endif /* _ASM_X86_DIV64_H */ |