49 lines
1.2 KiB
C
49 lines
1.2 KiB
C
#ifndef __I386_DIV64
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#define __I386_DIV64
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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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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):"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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/*
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* (long)X = ((long long)divs) / (long)div
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* (long)rem = ((long long)divs) % (long)div
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*
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* Warning, this will do an exception if X overflows.
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*/
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#define div_long_long_rem(a,b,c) div_ll_X_l_rem(a,b,c)
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extern inline long
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div_ll_X_l_rem(long long divs, long div, long *rem)
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{
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long dum2;
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__asm__("divl %2":"=a"(dum2), "=d"(*rem)
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: "rm"(div), "A"(divs));
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return dum2;
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}
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#endif
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