div64.h

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#ifndef __I386_DIV64
#define __I386_DIV64

/*
 * do_div() is NOT a C function. It wants to return
 * two values (the quotient and the remainder), but
 * since that doesn't work very well in C, what it
 * does is:
 *
 * - modifies the 64-bit dividend _in_place_
 * - returns the 32-bit remainder
 *
 * This ends up being the most efficient "calling
 * convention" on x86.
 */
#define do_div(n,base) ({ \
        unsigned long __upper, __low, __high, __mod, __base; \
        __base = (base); \
        asm("":"=a" (__low), "=d" (__high):"A" (n)); \
        __upper = __high; \
        if (__high) { \
                __upper = __high % (__base); \
                __high = __high / (__base); \
        } \
        asm("divl %2":"=a" (__low), "=d" (__mod):"rm" (__base), "0" (__low), "1" (__upper)); \
        asm("":"=A" (n):"a" (__low),"d" (__high)); \
        __mod; \
})

/*
 * (long)X = ((long long)divs) / (long)div
 * (long)rem = ((long long)divs) % (long)div
 *
 * Warning, this will do an exception if X overflows.
 */
#define div_long_long_rem(a,b,c) div_ll_X_l_rem(a,b,c)

extern inline long
div_ll_X_l_rem(long long divs, long div, long *rem)
{
        long dum2;
      __asm__("divl %2":"=a"(dum2), "=d"(*rem)
      : "rm"(div), "A"(divs));

        return dum2;

}
#endif

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