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110 lines
4.1 KiB
C
110 lines
4.1 KiB
C
/* Software floating-point emulation.
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Basic eight-word fraction declaration and manipulation.
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Copyright (C) 1997,1998,1999,2006 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Richard Henderson (rth@cygnus.com),
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Jakub Jelinek (jj@ultra.linux.cz) and
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Peter Maydell (pmaydell@chiark.greenend.org.uk).
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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In addition to the permissions in the GNU Lesser General Public
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License, the Free Software Foundation gives you unlimited
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permission to link the compiled version of this file into
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combinations with other programs, and to distribute those
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combinations without any restriction coming from the use of this
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file. (The Lesser General Public License restrictions do apply in
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other respects; for example, they cover modification of the file,
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and distribution when not linked into a combine executable.)
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* We need just a few things from here for op-4, if we ever need some
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other macros, they can be added. */
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#define _FP_FRAC_DECL_8(X) _FP_W_TYPE X##_f[8]
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#define _FP_FRAC_HIGH_8(X) (X##_f[7])
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#define _FP_FRAC_LOW_8(X) (X##_f[0])
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#define _FP_FRAC_WORD_8(X,w) (X##_f[w])
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#define _FP_FRAC_SLL_8(X,N) \
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do { \
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_FP_I_TYPE _up, _down, _skip, _i; \
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_skip = (N) / _FP_W_TYPE_SIZE; \
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_up = (N) % _FP_W_TYPE_SIZE; \
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_down = _FP_W_TYPE_SIZE - _up; \
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if (!_up) \
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for (_i = 7; _i >= _skip; --_i) \
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X##_f[_i] = X##_f[_i-_skip]; \
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else \
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{ \
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for (_i = 7; _i > _skip; --_i) \
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X##_f[_i] = X##_f[_i-_skip] << _up \
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| X##_f[_i-_skip-1] >> _down; \
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X##_f[_i--] = X##_f[0] << _up; \
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} \
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for (; _i >= 0; --_i) \
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X##_f[_i] = 0; \
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} while (0)
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#define _FP_FRAC_SRL_8(X,N) \
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do { \
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_FP_I_TYPE _up, _down, _skip, _i; \
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_skip = (N) / _FP_W_TYPE_SIZE; \
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_down = (N) % _FP_W_TYPE_SIZE; \
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_up = _FP_W_TYPE_SIZE - _down; \
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if (!_down) \
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for (_i = 0; _i <= 7-_skip; ++_i) \
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X##_f[_i] = X##_f[_i+_skip]; \
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else \
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{ \
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for (_i = 0; _i < 7-_skip; ++_i) \
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X##_f[_i] = X##_f[_i+_skip] >> _down \
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| X##_f[_i+_skip+1] << _up; \
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X##_f[_i++] = X##_f[7] >> _down; \
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} \
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for (; _i < 8; ++_i) \
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X##_f[_i] = 0; \
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} while (0)
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/* Right shift with sticky-lsb.
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* What this actually means is that we do a standard right-shift,
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* but that if any of the bits that fall off the right hand side
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* were one then we always set the LSbit.
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*/
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#define _FP_FRAC_SRS_8(X,N,size) \
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do { \
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_FP_I_TYPE _up, _down, _skip, _i; \
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_FP_W_TYPE _s; \
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_skip = (N) / _FP_W_TYPE_SIZE; \
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_down = (N) % _FP_W_TYPE_SIZE; \
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_up = _FP_W_TYPE_SIZE - _down; \
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for (_s = _i = 0; _i < _skip; ++_i) \
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_s |= X##_f[_i]; \
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if (!_down) \
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for (_i = 0; _i <= 7-_skip; ++_i) \
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X##_f[_i] = X##_f[_i+_skip]; \
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else \
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{ \
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_s |= X##_f[_i] << _up; \
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for (_i = 0; _i < 7-_skip; ++_i) \
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X##_f[_i] = X##_f[_i+_skip] >> _down \
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| X##_f[_i+_skip+1] << _up; \
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X##_f[_i++] = X##_f[7] >> _down; \
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} \
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for (; _i < 8; ++_i) \
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X##_f[_i] = 0; \
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/* don't fix the LSB until the very end when we're sure f[0] is stable */ \
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X##_f[0] |= (_s != 0); \
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} while (0)
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