ArmPkg/Library/CompilerIntrinsicsLib/Arm/ctzsi2.S

   1 #------------------------------------------------------------------------------
   2 #
   3 # Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
   4 #
   5 # This program and the accompanying materials
   6 # are licensed and made available under the terms and conditions of the BSD License
   7 # which accompanies this distribution.  The full text of the license may be found at
   8 # http://opensource.org/licenses/bsd-license.php
   9 #
  10 # THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12 #
  13 #------------------------------------------------------------------------------
  14
  15 #include <AsmMacroIoLib.h>
  16
  17 ASM_FUNC(__ctzsi2)
  18   uxth  r3, r0
  19   cmp  r3, #0
  20   moveq  ip, #16
  21   movne  ip, #0
  22   @ lr needed for prologue
  23   mov  r0, r0, lsr ip
  24   tst  r0, #255
  25   movne  r3, #0
  26   moveq  r3, #8
  27   mov  r0, r0, lsr r3
  28   tst  r0, #15
  29   movne  r1, #0
  30   moveq  r1, #4
  31   add  r3, r3, ip
  32   mov  r0, r0, lsr r1
  33   tst  r0, #3
  34   movne  r2, #0
  35   moveq  r2, #2
  36   add  r3, r3, r1
  37   mov  r0, r0, lsr r2
  38   and  r0, r0, #3
  39   add  r2, r3, r2
  40   eor  r3, r0, #1
  41   mov  r0, r0, lsr #1
  42   ands  r3, r3, #1
  43   mvnne  r3, #0
  44   rsb  r0, r0, #2
  45   and  r0, r3, r0
  46   add  r0, r2, r0
  47   bx  lr