From bb8985586b7a906e116db835c64773b7a7d51663 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 17 Aug 2008 21:05:42 -0400 Subject: x86, um: ... and asm-x86 move Signed-off-by: Al Viro Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/div64.h | 60 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100644 arch/x86/include/asm/div64.h (limited to 'arch/x86/include/asm/div64.h') diff --git a/arch/x86/include/asm/div64.h b/arch/x86/include/asm/div64.h new file mode 100644 index 00000000000..f9530f23f1d --- /dev/null +++ b/arch/x86/include/asm/div64.h @@ -0,0 +1,60 @@ +#ifndef ASM_X86__DIV64_H +#define ASM_X86__DIV64_H + +#ifdef CONFIG_X86_32 + +#include + +/* + * 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; \ +}) + +static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) +{ + union { + u64 v64; + u32 v32[2]; + } d = { dividend }; + u32 upper; + + upper = d.v32[1]; + d.v32[1] = 0; + if (upper >= divisor) { + d.v32[1] = upper / divisor; + upper %= divisor; + } + asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) : + "rm" (divisor), "0" (d.v32[0]), "1" (upper)); + return d.v64; +} +#define div_u64_rem div_u64_rem + +#else +# include +#endif /* CONFIG_X86_32 */ + +#endif /* ASM_X86__DIV64_H */ -- cgit v1.2.3 From 1965aae3c98397aad957412413c07e97b1bd4e64 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Wed, 22 Oct 2008 22:26:29 -0700 Subject: x86: Fix ASM_X86__ header guards Change header guards named "ASM_X86__*" to "_ASM_X86_*" since: a. the double underscore is ugly and pointless. b. no leading underscore violates namespace constraints. Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/div64.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/x86/include/asm/div64.h') diff --git a/arch/x86/include/asm/div64.h b/arch/x86/include/asm/div64.h index f9530f23f1d..9a2d644c08e 100644 --- a/arch/x86/include/asm/div64.h +++ b/arch/x86/include/asm/div64.h @@ -1,5 +1,5 @@ -#ifndef ASM_X86__DIV64_H -#define ASM_X86__DIV64_H +#ifndef _ASM_X86_DIV64_H +#define _ASM_X86_DIV64_H #ifdef CONFIG_X86_32 @@ -57,4 +57,4 @@ static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) # include #endif /* CONFIG_X86_32 */ -#endif /* ASM_X86__DIV64_H */ +#endif /* _ASM_X86_DIV64_H */ -- cgit v1.2.3