sysdeps/mips/fpu_control.h

   1 /* FPU control word bits.  Mips version.
   2    Copyright (C) 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Olaf Flebbe and Ralf Baechle.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #ifndef _FPU_CONTROL_H
  22 #define _FPU_CONTROL_H
  23
  24 /* MIPS FPU floating point control register bits.
  25  *
  26  * 31-25  -> floating point conditions code bits 7-1.  These bits are only
  27  *           available in MIPS IV.
  28  * 24     -> flush denormalized results to zero instead of
  29  *           causing unimplemented operation exception.  This bit is only
  30  *           available for MIPS III and newer.
  31  * 23     -> Condition bit
  32  * 22-18  -> reserved (read as 0, write with 0)
  33  * 17     -> cause bit for unimplemented operation
  34  * 16     -> cause bit for invalid exception
  35  * 15     -> cause bit for division by zero exception
  36  * 14     -> cause bit for overflow exception
  37  * 13     -> cause bit for underflow exception
  38  * 12     -> cause bit for inexact exception
  39  * 11     -> enable exception for invalid exception
  40  * 10     -> enable exception for division by zero exception
  41  *  9     -> enable exception for overflow exception
  42  *  8     -> enable exception for underflow exception
  43  *  7     -> enable exception for inexact exception
  44  *  6     -> flag invalid exception
  45  *  5     -> flag division by zero exception
  46  *  4     -> flag overflow exception
  47  *  3     -> flag underflow exception
  48  *  2     -> flag inexact exception
  49  *  1-0   -> rounding control
  50  *
  51  *
  52  * Rounding Control:
  53  * 00 - rounding to nearest (RN)
  54  * 01 - rounding toward zero (RZ)
  55  * 10 - rounding (up) toward plus infinity (RP)
  56  * 11 - rounding (down)toward minus infinity (RM)
  57  */
  58
  59 #include <features.h>
  60
  61 /* masking of interrupts */
  62 #define _FPU_MASK_V     0x0800  /* Invalid operation */
  63 #define _FPU_MASK_Z     0x0400  /* Division by zero  */
  64 #define _FPU_MASK_O     0x0200  /* Overflow          */
  65 #define _FPU_MASK_U     0x0100  /* Underflow         */
  66 #define _FPU_MASK_I     0x0080  /* Inexact operation */
  67
  68 /* flush denormalized numbers to zero */
  69 #define _FPU_FLUSH_TZ   0x1000000
  70
  71 /* rounding control */
  72 #define _FPU_RC_NEAREST 0x0     /* RECOMMENDED */
  73 #define _FPU_RC_ZERO    0x1
  74 #define _FPU_RC_UP      0x2
  75 #define _FPU_RC_DOWN    0x3
  76
  77 #define _FPU_RESERVED 0xfe3c0000  /* Reserved bits in cw */
  78
  79
  80 /* The fdlibm code requires strict IEEE double precision arithmetic,
  81    and no interrupts for exceptions, rounding to nearest.  */
  82
  83 #define _FPU_DEFAULT  0x00000000
  84
  85 /* IEEE:  same as above, but exceptions */
  86 #define _FPU_IEEE     0x00000F80
  87
  88 /* Type of the control word.  */
  89 typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__SI__)));
  90
  91 /* Macros for accessing the hardware control word.  */
  92 #define _FPU_GETCW(cw) __asm__ ("cfc1 %0,$31" : "=r" (cw))
  93 #define _FPU_SETCW(cw) __asm__ ("ctc1 %0,$31" : : "r" (cw))
  94
  95 /* Default control word set at startup.  */
  96 extern fpu_control_t __fpu_control;
  97
  98 #endif  /* fpu_control.h */