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Viewing changes to arch/x86/include/asm/div64.h

  • Committer: Package Import Robot
  • Author(s): Alessio Igor Bogani
  • Date: 2011-10-26 11:13:05 UTC
  • Revision ID: package-import@ubuntu.com-20111026111305-tz023xykf0i6eosh
Tags: upstream-3.2.0
Import upstream version 3.2.0

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arch/x86/include/asm/div64.h
 
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#ifndef _ASM_X86_DIV64_H
 
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#define _ASM_X86_DIV64_H
 
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#ifdef CONFIG_X86_32
 
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#include <linux/types.h>
 
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/*
 
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 * do_div() is NOT a C function. It wants to return
 
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 * two values (the quotient and the remainder), but
 
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 * since that doesn't work very well in C, what it
 
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 * does is:
 
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 *
 
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 * - modifies the 64-bit dividend _in_place_
 
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 * - returns the 32-bit remainder
 
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 *
 
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 * This ends up being the most efficient "calling
 
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 * convention" on x86.
 
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 */
 
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#define do_div(n, base)                                         \
 
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({                                                              \
 
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        unsigned long __upper, __low, __high, __mod, __base;    \
 
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        __base = (base);                                        \
 
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        asm("":"=a" (__low), "=d" (__high) : "A" (n));          \
 
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        __upper = __high;                                       \
 
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        if (__high) {                                           \
 
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                __upper = __high % (__base);                    \
 
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                __high = __high / (__base);                     \
 
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        }                                                       \
 
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        asm("divl %2":"=a" (__low), "=d" (__mod)                \
 
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            : "rm" (__base), "0" (__low), "1" (__upper));       \
 
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        asm("":"=A" (n) : "a" (__low), "d" (__high));           \
 
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        __mod;                                                  \
 
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})
 
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static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
 
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{
 
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        union {
 
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                u64 v64;
 
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                u32 v32[2];
 
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        } d = { dividend };
 
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        u32 upper;
 
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        upper = d.v32[1];
 
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        d.v32[1] = 0;
 
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        if (upper >= divisor) {
 
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                d.v32[1] = upper / divisor;
 
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                upper %= divisor;
 
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        }
 
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        asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
 
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                "rm" (divisor), "0" (d.v32[0]), "1" (upper));
 
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        return d.v64;
 
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}
 
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#define div_u64_rem     div_u64_rem
 
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#else
 
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# include <asm-generic/div64.h>
 
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#endif /* CONFIG_X86_32 */
 
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#endif /* _ASM_X86_DIV64_H */