sysdeps/mips/fpu_control.h

   1 /* FPU control word bits.  Mips version.
   2    Copyright (C) 1996-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _FPU_CONTROL_H
  20 #define _FPU_CONTROL_H
  21
  22 /* MIPS FPU floating point control register bits.
  23  *
  24  * 31-25  -> floating point conditions code bits 7-1.  These bits are only
  25  *           available in MIPS IV.
  26  * 24     -> flush denormalized results to zero instead of
  27  *           causing unimplemented operation exception.  This bit is only
  28  *           available for MIPS III and newer.
  29  * 23     -> Condition bit
  30  * 22-21  -> reserved for architecture implementers
  31  * 20     -> reserved (read as 0, write with 0)
  32  * 19     -> IEEE 754-2008 non-arithmetic ABS.fmt and NEG.fmt enable
  33  * 18     -> IEEE 754-2008 recommended NaN encoding enable
  34  * 17     -> cause bit for unimplemented operation
  35  * 16     -> cause bit for invalid exception
  36  * 15     -> cause bit for division by zero exception
  37  * 14     -> cause bit for overflow exception
  38  * 13     -> cause bit for underflow exception
  39  * 12     -> cause bit for inexact exception
  40  * 11     -> enable exception for invalid exception
  41  * 10     -> enable exception for division by zero exception
  42  *  9     -> enable exception for overflow exception
  43  *  8     -> enable exception for underflow exception
  44  *  7     -> enable exception for inexact exception
  45  *  6     -> flag invalid exception
  46  *  5     -> flag division by zero exception
  47  *  4     -> flag overflow exception
  48  *  3     -> flag underflow exception
  49  *  2     -> flag inexact exception
  50  *  1-0   -> rounding control
  51  *
  52  *
  53  * Rounding Control:
  54  * 00 - rounding to nearest (RN)
  55  * 01 - rounding toward zero (RZ)
  56  * 10 - rounding (up) toward plus infinity (RP)
  57  * 11 - rounding (down)toward minus infinity (RM)
  58  */
  59
  60 #include <features.h>
  61
  62 #ifdef __mips_soft_float
  63
  64 #define _FPU_RESERVED 0xffffffff
  65 #define _FPU_DEFAULT  0x00000000
  66 typedef unsigned int fpu_control_t;
  67 #define _FPU_GETCW(cw) (cw) = 0
  68 #define _FPU_SETCW(cw) (void) (cw)
  69 extern fpu_control_t __fpu_control;
  70
  71 #else /* __mips_soft_float */
  72
  73 /* Masks for interrupts.  */
  74 #define _FPU_MASK_V     0x0800  /* Invalid operation */
  75 #define _FPU_MASK_Z     0x0400  /* Division by zero  */
  76 #define _FPU_MASK_O     0x0200  /* Overflow          */
  77 #define _FPU_MASK_U     0x0100  /* Underflow         */
  78 #define _FPU_MASK_I     0x0080  /* Inexact operation */
  79
  80 /* Flush denormalized numbers to zero.  */
  81 #define _FPU_FLUSH_TZ   0x1000000
  82
  83 /* IEEE 754-2008 compliance control.  */
  84 #define _FPU_ABS2008    0x80000
  85 #define _FPU_NAN2008    0x40000
  86
  87 /* Rounding control.  */
  88 #define _FPU_RC_NEAREST 0x0     /* RECOMMENDED */
  89 #define _FPU_RC_ZERO    0x1
  90 #define _FPU_RC_UP      0x2
  91 #define _FPU_RC_DOWN    0x3
  92 /* Mask for rounding control.  */
  93 #define _FPU_RC_MASK    0x3
  94
  95 #define _FPU_RESERVED 0xfe8c0000  /* Reserved bits in cw, incl ABS/NAN2008.  */
  96
  97
  98 /* The fdlibm code requires strict IEEE double precision arithmetic,
  99    and no interrupts for exceptions, rounding to nearest.  */
 100 #ifdef __mips_nan2008
 101 # define _FPU_DEFAULT 0x000C0000
 102 #else
 103 # define _FPU_DEFAULT 0x00000000
 104 #endif
 105
 106 /* IEEE: same as above, but exceptions.  */
 107 #ifdef __mips_nan2008
 108 # define _FPU_IEEE    0x000C0F80
 109 #else
 110 # define _FPU_IEEE    0x00000F80
 111 #endif
 112
 113 /* Type of the control word.  */
 114 typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__SI__)));
 115
 116 /* Macros for accessing the hardware control word.  */
 117 extern fpu_control_t __mips_fpu_getcw (void) __THROW;
 118 extern void __mips_fpu_setcw (fpu_control_t) __THROW;
 119 #ifdef __mips16
 120 # define _FPU_GETCW(cw) do { (cw) = __mips_fpu_getcw (); } while (0)
 121 # define _FPU_SETCW(cw) __mips_fpu_setcw (cw)
 122 #else
 123 # define _FPU_GETCW(cw) __asm__ volatile ("cfc1 %0,$31" : "=r" (cw))
 124 # define _FPU_SETCW(cw) __asm__ volatile ("ctc1 %0,$31" : : "r" (cw))
 125 #endif
 126
 127 /* Default control word set at startup.  */
 128 extern fpu_control_t __fpu_control;
 129
 130 #endif /* __mips_soft_float */
 131
 132 #endif  /* fpu_control.h */