fpu_control.h 3.3 KB

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  1. /* FPU control word bits. Alpha-mapped-to-Intel version.
  2. Copyright (C) 1996, 1998, 2000, 2002 Free Software Foundation, Inc.
  3. This file is part of the GNU C Library.
  4. Contributed by Olaf Flebbe.
  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. The GNU C Library is distributed in the hope that it will be useful,
  10. but WITHOUT ANY WARRANTY; without even the implied warranty of
  11. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  12. Lesser General Public License for more details.
  13. You should have received a copy of the GNU Lesser General Public
  14. License along with the GNU C Library; if not, write to the Free
  15. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  16. 02111-1307 USA. */
  17. #ifndef _ALPHA_FPU_CONTROL_H
  18. #define _ALPHA_FPU_CONTROL_H
  19. /*
  20. * Since many programs seem to hardcode the values passed to __setfpucw()
  21. * (rather than using the manifest constants) we emulate the x87 interface
  22. * here (at least where this makes sense).
  23. *
  24. * 15-13 12 11-10 9-8 7-6 5 4 3 2 1 0
  25. * | reserved | IC | RC | PC | reserved | PM | UM | OM | ZM | DM | IM
  26. *
  27. * IM: Invalid operation mask
  28. * DM: Denormalized operand mask
  29. * ZM: Zero-divide mask
  30. * OM: Overflow mask
  31. * UM: Underflow mask
  32. * PM: Precision (inexact result) mask
  33. *
  34. * Mask bit is 1 means no interrupt.
  35. *
  36. * PC: Precision control
  37. * 11 - round to extended precision
  38. * 10 - round to double precision
  39. * 00 - round to single precision
  40. *
  41. * RC: Rounding control
  42. * 00 - rounding to nearest
  43. * 01 - rounding down (toward - infinity)
  44. * 10 - rounding up (toward + infinity)
  45. * 11 - rounding toward zero
  46. *
  47. * IC: Infinity control
  48. * That is for 8087 and 80287 only.
  49. *
  50. * The hardware default is 0x037f. I choose 0x1372.
  51. */
  52. #include <features.h>
  53. /* masking of interrupts */
  54. #define _FPU_MASK_IM 0x01
  55. #define _FPU_MASK_DM 0x02
  56. #define _FPU_MASK_ZM 0x04
  57. #define _FPU_MASK_OM 0x08
  58. #define _FPU_MASK_UM 0x10
  59. #define _FPU_MASK_PM 0x20
  60. /* precision control -- without effect on Alpha */
  61. #define _FPU_EXTENDED 0x300 /* RECOMMENDED */
  62. #define _FPU_DOUBLE 0x200
  63. #define _FPU_SINGLE 0x0 /* DO NOT USE */
  64. /*
  65. * rounding control---notice that on the Alpha this affects only
  66. * instructions with the dynamic rounding mode qualifier (/d).
  67. */
  68. #define _FPU_RC_NEAREST 0x000 /* RECOMMENDED */
  69. #define _FPU_RC_DOWN 0x400
  70. #define _FPU_RC_UP 0x800
  71. #define _FPU_RC_ZERO 0xC00
  72. #define _FPU_RESERVED 0xF0C0 /* Reserved bits in cw */
  73. /* Now two recommended cw */
  74. /* Linux default:
  75. - extended precision
  76. - rounding to positive infinity. There is no /p instruction
  77. qualifier. By setting the dynamic rounding mode to +infinity,
  78. one can use /d to get round to +infinity with no extra overhead
  79. (so long as the default isn't changed, of course...)
  80. - no exceptions enabled. */
  81. #define _FPU_DEFAULT 0x137f
  82. /* IEEE: same as above. */
  83. #define _FPU_IEEE 0x137f
  84. /* Type of the control word. */
  85. typedef unsigned int fpu_control_t;
  86. #if 0
  87. /* Default control word set at startup. */
  88. extern fpu_control_t __fpu_control;
  89. #endif
  90. #endif /* _ALPHA_FPU_CONTROL */