File: /Users/paulross/dev/linux/linux-3.13/arch/x86/include/asm/arch_hweight.h

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       1: #ifndef _ASM_X86_HWEIGHT_H
       2: #define _ASM_X86_HWEIGHT_H
       3: 
       4: #ifdef CONFIG_64BIT
       5: /* popcnt %edi, %eax -- redundant REX prefix for alignment */
       6: #define POPCNT32 ".byte 0xf3,0x40,0x0f,0xb8,0xc7"
       7: /* popcnt %rdi, %rax */
       8: #define POPCNT64 ".byte 0xf3,0x48,0x0f,0xb8,0xc7"
       9: #define REG_IN "D"
      10: #define REG_OUT "a"
      11: #else
      12: /* popcnt %eax, %eax */
      13: #define POPCNT32 ".byte 0xf3,0x0f,0xb8,0xc0"
      14: #define REG_IN "a"
      15: #define REG_OUT "a"
      16: #endif
      17: 
      18: /*
      19:  * __sw_hweightXX are called from within the alternatives below
      20:  * and callee-clobbered registers need to be taken care of. See
      21:  * ARCH_HWEIGHT_CFLAGS in <arch/x86/Kconfig> for the respective
      22:  * compiler switches.
      23:  */
      24: static inline unsigned int __arch_hweight32(unsigned int w)
      25: {
      26:     unsigned int res = 0;
      27: 
      28:     asm (ALTERNATIVE("call __sw_hweight32", POPCNT32, X86_FEATURE_POPCNT)
      29:              : "="REG_OUT (res)
      30:              : REG_IN (w));
      31: 
      32:     return res;
      33: }
      34: 
      35: static inline unsigned int __arch_hweight16(unsigned int w)
      36: {
      37:     return __arch_hweight32(w & 0xffff);
      38: }
      39: 
      40: static inline unsigned int __arch_hweight8(unsigned int w)
      41: {
      42:     return __arch_hweight32(w & 0xff);
      43: }
      44: 
      45: static inline unsigned long __arch_hweight64(__u64 w)
      46: {
      47:     unsigned long res = 0;
      48: 
      49: #ifdef CONFIG_X86_32
      50:     return  __arch_hweight32((u32)w) +
      51:         __arch_hweight32((u32)(w >> 32));
      52: #else
      53:     asm (ALTERNATIVE("call __sw_hweight64", POPCNT64, X86_FEATURE_POPCNT)
      54:              : "="REG_OUT (res)
      55:              : REG_IN (w));
      56: #endif /* CONFIG_X86_32 */
      57: 
      58:     return res;
      59: }
      60: 
      61: #endif
      62: