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

  • Committer: Bazaar Package Importer
  • Author(s): Mathieu Poirier
  • Date: 2011-02-18 09:43:31 UTC
  • Revision ID: james.westby@ubuntu.com-20110218094331-eyubsja4f9k0yhmq
Tags: 2.6.35-1.1
Initial release.

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arch/x86/include/asm/arch_hweight.h
 
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#ifndef _ASM_X86_HWEIGHT_H
 
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#define _ASM_X86_HWEIGHT_H
 
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#ifdef CONFIG_64BIT
 
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/* popcnt %edi, %eax -- redundant REX prefix for alignment */
 
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#define POPCNT32 ".byte 0xf3,0x40,0x0f,0xb8,0xc7"
 
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/* popcnt %rdi, %rax */
 
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#define POPCNT64 ".byte 0xf3,0x48,0x0f,0xb8,0xc7"
 
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#define REG_IN "D"
 
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#define REG_OUT "a"
 
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#else
 
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/* popcnt %eax, %eax */
 
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#define POPCNT32 ".byte 0xf3,0x0f,0xb8,0xc0"
 
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#define REG_IN "a"
 
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#define REG_OUT "a"
 
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#endif
 
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/*
 
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 * __sw_hweightXX are called from within the alternatives below
 
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 * and callee-clobbered registers need to be taken care of. See
 
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 * ARCH_HWEIGHT_CFLAGS in <arch/x86/Kconfig> for the respective
 
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 * compiler switches.
 
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 */
 
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static inline unsigned int __arch_hweight32(unsigned int w)
 
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{
 
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        unsigned int res = 0;
 
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        asm (ALTERNATIVE("call __sw_hweight32", POPCNT32, X86_FEATURE_POPCNT)
 
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                     : "="REG_OUT (res)
 
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                     : REG_IN (w));
 
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        return res;
 
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}
 
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static inline unsigned int __arch_hweight16(unsigned int w)
 
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{
 
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        return __arch_hweight32(w & 0xffff);
 
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}
 
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static inline unsigned int __arch_hweight8(unsigned int w)
 
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{
 
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        return __arch_hweight32(w & 0xff);
 
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}
 
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static inline unsigned long __arch_hweight64(__u64 w)
 
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{
 
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        unsigned long res = 0;
 
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#ifdef CONFIG_X86_32
 
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        return  __arch_hweight32((u32)w) +
 
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                __arch_hweight32((u32)(w >> 32));
 
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#else
 
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        asm (ALTERNATIVE("call __sw_hweight64", POPCNT64, X86_FEATURE_POPCNT)
 
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                     : "="REG_OUT (res)
 
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                     : REG_IN (w));
 
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#endif /* CONFIG_X86_32 */
 
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        return res;
 
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}
 
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#endif