reactos/lib/rtl/i386/uallshr_asm.s

   1 /*
   2  * COPYRIGHT:         See COPYING in the top level directory
   3  * PROJECT:           ReactOS kernel
   4  * PURPOSE:           Run-Time Library
   5  * FILE:              lib/rtl/i386/ullshr.S
   6  * PROGRAMER:         Alex Ionescu (alex@relsoft.net)
   7  *                    Eric Kohl (ekohl@rz-online.de)
   8  *
   9  * Copyright (C) 2002 Michael Ringgaard.
  10  * All rights reserved.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  *
  16  * 1. Redistributions of source code must retain the above copyright
  17  *    notice, this list of conditions and the following disclaimer.
  18  * 2. Redistributions in binary form must reproduce the above copyright
  19  *    notice, this list of conditions and the following disclaimer in the
  20  *    documentation and/or other materials provided with the distribution.
  21  * 3. Neither the name of the project nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24
  25  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES// LOSS OF USE, DATA, OR PROFITS// OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  */
  37
  38 .globl __ullshr
  39
  40  /* DATA ********************************************************************/
  41
  42 fzero:
  43         .long   0                       // Floating point zero
  44         .long   0                       // Floating point zero
  45
  46 __fltused:
  47         .long 0x9875
  48
  49 .intel_syntax noprefix
  50
  51 /* FUNCTIONS ***************************************************************/
  52
  53 //
  54 // ullshr - long shift right
  55 //
  56 // Purpose:
  57 //       Does a unsigned Long Shift Right
  58 //       Shifts a long right any number of bits.
  59 //
  60 // Entry:
  61 //       EDX:EAX - long value to be shifted
  62 //       CL      - number of bits to shift by
  63 //
  64 // Exit:
  65 //       EDX:EAX - shifted value
  66 //
  67 // Uses:
  68 //       CL is destroyed.
  69 //
  70
  71 __aullshr:
  72
  73 //
  74 // Handle shifts of 64 bits or more (if shifting 64 bits or more, the result
  75 // depends only on the high order bit of edx).
  76 //
  77         cmp     cl,64
  78         jae     short ..RETZERO
  79
  80 //
  81 // Handle shifts of between 0 and 31 bits
  82 //
  83         cmp     cl, 32
  84         jae     short ..MORE32
  85         shrd    eax,edx,cl
  86         shr     edx,cl
  87         ret
  88
  89 //
  90 // Handle shifts of between 32 and 63 bits
  91 //
  92 ..MORE32:
  93         mov     eax,edx
  94         xor     edx,edx
  95         and     cl,31
  96         shr     eax,cl
  97         ret
  98
  99 //
 100 // return 0 in edx:eax
 101 //
 102 ..RETZERO:
 103         xor     eax,eax
 104         xor     edx,edx
 105         ret