63 lines
1.5 KiB
C
63 lines
1.5 KiB
C
#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 __always_inline unsigned int __arch_hweight32(unsigned int w)
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{
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unsigned int res = w - ((w >> 1) & 0x55555555);
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res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
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res = (res + (res >> 4)) & 0x0F0F0F0F;
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res = res + (res >> 8);
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return (res + (res >> 16)) & 0x000000FF;
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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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#ifdef CONFIG_X86_32
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static inline unsigned long __arch_hweight64(__u64 w)
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{
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return __arch_hweight32((u32)w) +
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__arch_hweight32((u32)(w >> 32));
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}
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#else
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static __always_inline unsigned long __arch_hweight64(__u64 w)
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{
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unsigned long res = 0;
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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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return res;
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}
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#endif /* CONFIG_X86_32 */
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#endif
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