reactos/lib/sdk/crt/math/amd64/floorf.S

   1 /*
   2  * COPYRIGHT:         See COPYING in the top level directory
   3  * PROJECT:           ReactOS system libraries
   4  * PURPOSE:           Implementation of tan
   5  * FILE:              lib/sdk/crt/math/amd64/floorf.S
   6  * PROGRAMMER:        Timo Kreuzer (timo.kreuzer@reactos.org)
   7  */
   8
   9 /* INCLUDES ******************************************************************/
  10
  11 #include <reactos/asm.h>
  12 #include <ndk/amd64/asm.h>
  13
  14 /* FUNCTIONS ****************************************************************/
  15
  16 .code64
  17
  18 PUBLIC floorf
  19 floorf:
  20     /* Put parameter on the stack */
  21     movss [rsp - 0x10], xmm0
  22     fld   dword ptr [rsp]
  23
  24     /* Change fpu control word to round down */
  25     fstcw [rsp - 0x10]
  26     mov   eax, [rsp - 0x10]
  27     or    eax, 0x00400
  28     and   eax, 0x0f7ff
  29     mov   [rsp - 0x08], eax
  30     fldcw [rsp - 0x08]
  31
  32     /* Round to integer */
  33     frndint
  34
  35     /* Restore fpu control word */
  36     fldcw [rsp - 0x10]
  37
  38     fstp  dword ptr [rsp - 0x10]
  39     movss xmm0, [rsp - 0x10]
  40     ret