strrev

0000000000000000 <strrev>:
   0:   31 c0                   xor    eax,eax
   2:   48 8d 48 ff             lea    rcx,[rax-0x1]
   6:   48 89 fe                mov    rsi,rdi
   9:   f2 ae                   repnz scas al,BYTE PTR es:[rdi]
   b:   48 f7 d1                not    rcx
   e:   48 d1 e9                shr    rcx,1
  11:   48 ff cf                dec    rdi
  14:   48 ff cf                dec    rdi
  17:   ac                      lods   al,BYTE PTR ds:[rsi]
  18:   86 07                   xchg   BYTE PTR [rdi],al
  1a:   88 46 ff                mov    BYTE PTR [rsi-0x1],al
  1d:   e2 f5                   loop   14 <strrev+0x14>
  1f:   c3                      ret