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