libc/sysdeps/linux/m68k/fpu_control.h

   1 /* 68k FPU control word definitions.
   2    Copyright (C) 1996, 1997, 1998 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _FPU_CONTROL_H
  20 #define _FPU_CONTROL_H
  21
  22 /*
  23  * Motorola floating point control register bits.
  24  *
  25  * 31-16  -> reserved (read as 0, ignored on write)
  26  * 15     -> enable trap for BSUN exception
  27  * 14     -> enable trap for SNAN exception
  28  * 13     -> enable trap for OPERR exception
  29  * 12     -> enable trap for OVFL exception
  30  * 11     -> enable trap for UNFL exception
  31  * 10     -> enable trap for DZ exception
  32  *  9     -> enable trap for INEX2 exception
  33  *  8     -> enable trap for INEX1 exception
  34  *  7-6   -> Precision Control
  35  *  5-4   -> Rounding Control
  36  *  3-0   -> zero (read as 0, write as 0)
  37  *
  38  *
  39  * Precision Control:
  40  * 00 - round to extended precision
  41  * 01 - round to single precision
  42  * 10 - round to double precision
  43  * 11 - undefined
  44  *
  45  * Rounding Control:
  46  * 00 - rounding to nearest (RN)
  47  * 01 - rounding toward zero (RZ)
  48  * 10 - rounding (down)toward minus infinity (RM)
  49  * 11 - rounding (up) toward plus infinity (RP)
  50  *
  51  * The hardware default is 0x0000. I choose 0x5400.
  52  */
  53
  54 #include <features.h>
  55
  56 /* masking of interrupts */
  57 #define _FPU_MASK_BSUN  0x8000
  58 #define _FPU_MASK_SNAN  0x4000
  59 #define _FPU_MASK_OPERR 0x2000
  60 #define _FPU_MASK_OVFL  0x1000
  61 #define _FPU_MASK_UNFL  0x0800
  62 #define _FPU_MASK_DZ    0x0400
  63 #define _FPU_MASK_INEX1 0x0200
  64 #define _FPU_MASK_INEX2 0x0100
  65
  66 /* precision control */
  67 #define _FPU_EXTENDED 0x00   /* RECOMMENDED */
  68 #define _FPU_DOUBLE   0x80
  69 #define _FPU_SINGLE   0x40     /* DO NOT USE */
  70
  71 /* rounding control */
  72 #define _FPU_RC_NEAREST 0x00    /* RECOMMENDED */
  73 #define _FPU_RC_ZERO    0x10
  74 #define _FPU_RC_DOWN    0x20
  75 #define _FPU_RC_UP      0x30
  76
  77 #define _FPU_RESERVED 0xFFFF000F  /* Reserved bits in fpucr */
  78
  79
  80 /* Now two recommended fpucr */
  81
  82 /* The fdlibm code requires no interrupts for exceptions.  Don't
  83    change the rounding mode, it would break long double I/O!  */
  84 #define _FPU_DEFAULT  0x00000000
  85
  86 /* IEEE:  same as above, but exceptions.  We must make it non-zero so
  87    that __setfpucw works.  This bit will be ignored.  */
  88 #define _FPU_IEEE     0x00000001
  89
  90 /* Type of the control word.  */
  91 typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__SI__)));
  92
  93 /* Macros for accessing the hardware control word.  */
  94 #define _FPU_GETCW(cw) __asm__ ("fmove%.l %!, %0" : "=dm" (cw))
  95 #define _FPU_SETCW(cw) __asm__ __volatile__ ("fmove%.l %0, %!" : : "dm" (cw))
  96
  97 #if 0
  98 /* Default control word set at startup.  */
  99 extern fpu_control_t __fpu_control;
 100 #endif
 101
 102 #endif /* _M68K_FPU_CONTROL_H */