f8bd2258e2
x86 is the only arch right now, which provides an optimized for div_long_long_rem and it has the downside that one has to be very careful that the divide doesn't overflow. The API is a little akward, as the arguments for the unsigned divide are signed. The signed version also doesn't handle a negative divisor and produces worse code on 64bit archs. There is little incentive to keep this API alive, so this converts the few users to the new API. Signed-off-by: Roman Zippel <zippel@linux-m68k.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: john stultz <johnstul@us.ibm.com> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
60 lines
1.4 KiB
C
60 lines
1.4 KiB
C
#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 */
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