arch/x86/include/asm/arch_hweight.h

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