linux/include/math-emu/op-1.h
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   1/* Software floating-point emulation.
   2   Basic one-word fraction declaration and manipulation.
   3   Copyright (C) 1997,1998,1999 Free Software Foundation, Inc.
   4   This file is part of the GNU C Library.
   5   Contributed by Richard Henderson (rth@cygnus.com),
   6                  Jakub Jelinek (jj@ultra.linux.cz),
   7                  David S. Miller (davem@redhat.com) and
   8                  Peter Maydell (pmaydell@chiark.greenend.org.uk).
   9
  10   The GNU C Library is free software; you can redistribute it and/or
  11   modify it under the terms of the GNU Library General Public License as
  12   published by the Free Software Foundation; either version 2 of the
  13   License, or (at your option) any later version.
  14
  15   The GNU C Library is distributed in the hope that it will be useful,
  16   but WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18   Library General Public License for more details.
  19
  20   You should have received a copy of the GNU Library General Public
  21   License along with the GNU C Library; see the file COPYING.LIB.  If
  22   not, write to the Free Software Foundation, Inc.,
  23   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  24
  25#ifndef    __MATH_EMU_OP_1_H__
  26#define    __MATH_EMU_OP_1_H__
  27
  28#define _FP_FRAC_DECL_1(X)      _FP_W_TYPE X##_f=0
  29#define _FP_FRAC_COPY_1(D,S)    (D##_f = S##_f)
  30#define _FP_FRAC_SET_1(X,I)     (X##_f = I)
  31#define _FP_FRAC_HIGH_1(X)      (X##_f)
  32#define _FP_FRAC_LOW_1(X)       (X##_f)
  33#define _FP_FRAC_WORD_1(X,w)    (X##_f)
  34
  35#define _FP_FRAC_ADDI_1(X,I)    (X##_f += I)
  36#define _FP_FRAC_SLL_1(X,N)                     \
  37  do {                                          \
  38    if (__builtin_constant_p(N) && (N) == 1)    \
  39      X##_f += X##_f;                           \
  40    else                                        \
  41      X##_f <<= (N);                            \
  42  } while (0)
  43#define _FP_FRAC_SRL_1(X,N)     (X##_f >>= N)
  44
  45/* Right shift with sticky-lsb.  */
  46#define _FP_FRAC_SRS_1(X,N,sz)  __FP_FRAC_SRS_1(X##_f, N, sz)
  47
  48#define __FP_FRAC_SRS_1(X,N,sz)                                         \
  49   (X = (X >> (N) | (__builtin_constant_p(N) && (N) == 1                \
  50                     ? X & 1 : (X << (_FP_W_TYPE_SIZE - (N))) != 0)))
  51
  52#define _FP_FRAC_ADD_1(R,X,Y)   (R##_f = X##_f + Y##_f)
  53#define _FP_FRAC_SUB_1(R,X,Y)   (R##_f = X##_f - Y##_f)
  54#define _FP_FRAC_DEC_1(X,Y)     (X##_f -= Y##_f)
  55#define _FP_FRAC_CLZ_1(z, X)    __FP_CLZ(z, X##_f)
  56
  57/* Predicates */
  58#define _FP_FRAC_NEGP_1(X)      ((_FP_WS_TYPE)X##_f < 0)
  59#define _FP_FRAC_ZEROP_1(X)     (X##_f == 0)
  60#define _FP_FRAC_OVERP_1(fs,X)  (X##_f & _FP_OVERFLOW_##fs)
  61#define _FP_FRAC_CLEAR_OVERP_1(fs,X)    (X##_f &= ~_FP_OVERFLOW_##fs)
  62#define _FP_FRAC_EQ_1(X, Y)     (X##_f == Y##_f)
  63#define _FP_FRAC_GE_1(X, Y)     (X##_f >= Y##_f)
  64#define _FP_FRAC_GT_1(X, Y)     (X##_f > Y##_f)
  65
  66#define _FP_ZEROFRAC_1          0
  67#define _FP_MINFRAC_1           1
  68#define _FP_MAXFRAC_1           (~(_FP_WS_TYPE)0)
  69
  70/*
  71 * Unpack the raw bits of a native fp value.  Do not classify or
  72 * normalize the data.
  73 */
  74
  75#define _FP_UNPACK_RAW_1(fs, X, val)                            \
  76  do {                                                          \
  77    union _FP_UNION_##fs _flo; _flo.flt = (val);                \
  78                                                                \
  79    X##_f = _flo.bits.frac;                                     \
  80    X##_e = _flo.bits.exp;                                      \
  81    X##_s = _flo.bits.sign;                                     \
  82  } while (0)
  83
  84#define _FP_UNPACK_RAW_1_P(fs, X, val)                          \
  85  do {                                                          \
  86    union _FP_UNION_##fs *_flo =                                \
  87      (union _FP_UNION_##fs *)(val);                            \
  88                                                                \
  89    X##_f = _flo->bits.frac;                                    \
  90    X##_e = _flo->bits.exp;                                     \
  91    X##_s = _flo->bits.sign;                                    \
  92  } while (0)
  93
  94/*
  95 * Repack the raw bits of a native fp value.
  96 */
  97
  98#define _FP_PACK_RAW_1(fs, val, X)                              \
  99  do {                                                          \
 100    union _FP_UNION_##fs _flo;                                  \
 101                                                                \
 102    _flo.bits.frac = X##_f;                                     \
 103    _flo.bits.exp  = X##_e;                                     \
 104    _flo.bits.sign = X##_s;                                     \
 105                                                                \
 106    (val) = _flo.flt;                                           \
 107  } while (0)
 108
 109#define _FP_PACK_RAW_1_P(fs, val, X)                            \
 110  do {                                                          \
 111    union _FP_UNION_##fs *_flo =                                \
 112      (union _FP_UNION_##fs *)(val);                            \
 113                                                                \
 114    _flo->bits.frac = X##_f;                                    \
 115    _flo->bits.exp  = X##_e;                                    \
 116    _flo->bits.sign = X##_s;                                    \
 117  } while (0)
 118
 119
 120/*
 121 * Multiplication algorithms:
 122 */
 123
 124/* Basic.  Assuming the host word size is >= 2*FRACBITS, we can do the
 125   multiplication immediately.  */
 126
 127#define _FP_MUL_MEAT_1_imm(wfracbits, R, X, Y)                          \
 128  do {                                                                  \
 129    R##_f = X##_f * Y##_f;                                              \
 130    /* Normalize since we know where the msb of the multiplicands       \
 131       were (bit B), we know that the msb of the of the product is      \
 132       at either 2B or 2B-1.  */                                        \
 133    _FP_FRAC_SRS_1(R, wfracbits-1, 2*wfracbits);                        \
 134  } while (0)
 135
 136/* Given a 1W * 1W => 2W primitive, do the extended multiplication.  */
 137
 138#define _FP_MUL_MEAT_1_wide(wfracbits, R, X, Y, doit)                   \
 139  do {                                                                  \
 140    _FP_W_TYPE _Z_f0, _Z_f1;                                            \
 141    doit(_Z_f1, _Z_f0, X##_f, Y##_f);                                   \
 142    /* Normalize since we know where the msb of the multiplicands       \
 143       were (bit B), we know that the msb of the of the product is      \
 144       at either 2B or 2B-1.  */                                        \
 145    _FP_FRAC_SRS_2(_Z, wfracbits-1, 2*wfracbits);                       \
 146    R##_f = _Z_f0;                                                      \
 147  } while (0)
 148
 149/* Finally, a simple widening multiply algorithm.  What fun!  */
 150
 151#define _FP_MUL_MEAT_1_hard(wfracbits, R, X, Y)                         \
 152  do {                                                                  \
 153    _FP_W_TYPE _xh, _xl, _yh, _yl, _z_f0, _z_f1, _a_f0, _a_f1;          \
 154                                                                        \
 155    /* split the words in half */                                       \
 156    _xh = X##_f >> (_FP_W_TYPE_SIZE/2);                                 \
 157    _xl = X##_f & (((_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2)) - 1);         \
 158    _yh = Y##_f >> (_FP_W_TYPE_SIZE/2);                                 \
 159    _yl = Y##_f & (((_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2)) - 1);         \
 160                                                                        \
 161    /* multiply the pieces */                                           \
 162    _z_f0 = _xl * _yl;                                                  \
 163    _a_f0 = _xh * _yl;                                                  \
 164    _a_f1 = _xl * _yh;                                                  \
 165    _z_f1 = _xh * _yh;                                                  \
 166                                                                        \
 167    /* reassemble into two full words */                                \
 168    if ((_a_f0 += _a_f1) < _a_f1)                                       \
 169      _z_f1 += (_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2);                    \
 170    _a_f1 = _a_f0 >> (_FP_W_TYPE_SIZE/2);                               \
 171    _a_f0 = _a_f0 << (_FP_W_TYPE_SIZE/2);                               \
 172    _FP_FRAC_ADD_2(_z, _z, _a);                                         \
 173                                                                        \
 174    /* normalize */                                                     \
 175    _FP_FRAC_SRS_2(_z, wfracbits - 1, 2*wfracbits);                     \
 176    R##_f = _z_f0;                                                      \
 177  } while (0)
 178
 179
 180/*
 181 * Division algorithms:
 182 */
 183
 184/* Basic.  Assuming the host word size is >= 2*FRACBITS, we can do the
 185   division immediately.  Give this macro either _FP_DIV_HELP_imm for
 186   C primitives or _FP_DIV_HELP_ldiv for the ISO function.  Which you
 187   choose will depend on what the compiler does with divrem4.  */
 188
 189#define _FP_DIV_MEAT_1_imm(fs, R, X, Y, doit)           \
 190  do {                                                  \
 191    _FP_W_TYPE _q, _r;                                  \
 192    X##_f <<= (X##_f < Y##_f                            \
 193               ? R##_e--, _FP_WFRACBITS_##fs            \
 194               : _FP_WFRACBITS_##fs - 1);               \
 195    doit(_q, _r, X##_f, Y##_f);                         \
 196    R##_f = _q | (_r != 0);                             \
 197  } while (0)
 198
 199/* GCC's longlong.h defines a 2W / 1W => (1W,1W) primitive udiv_qrnnd
 200   that may be useful in this situation.  This first is for a primitive
 201   that requires normalization, the second for one that does not.  Look
 202   for UDIV_NEEDS_NORMALIZATION to tell which your machine needs.  */
 203
 204#define _FP_DIV_MEAT_1_udiv_norm(fs, R, X, Y)                           \
 205  do {                                                                  \
 206    _FP_W_TYPE _nh, _nl, _q, _r, _y;                                    \
 207                                                                        \
 208    /* Normalize Y -- i.e. make the most significant bit set.  */       \
 209    _y = Y##_f << _FP_WFRACXBITS_##fs;                                  \
 210                                                                        \
 211    /* Shift X op correspondingly high, that is, up one full word.  */  \
 212    if (X##_f < Y##_f)                                                  \
 213      {                                                                 \
 214        R##_e--;                                                        \
 215        _nl = 0;                                                        \
 216        _nh = X##_f;                                                    \
 217      }                                                                 \
 218    else                                                                \
 219      {                                                                 \
 220        _nl = X##_f << (_FP_W_TYPE_SIZE - 1);                           \
 221        _nh = X##_f >> 1;                                               \
 222      }                                                                 \
 223                                                                        \
 224    udiv_qrnnd(_q, _r, _nh, _nl, _y);                                   \
 225    R##_f = _q | (_r != 0);                                             \
 226  } while (0)
 227
 228#define _FP_DIV_MEAT_1_udiv(fs, R, X, Y)                \
 229  do {                                                  \
 230    _FP_W_TYPE _nh, _nl, _q, _r;                        \
 231    if (X##_f < Y##_f)                                  \
 232      {                                                 \
 233        R##_e--;                                        \
 234        _nl = X##_f << _FP_WFRACBITS_##fs;              \
 235        _nh = X##_f >> _FP_WFRACXBITS_##fs;             \
 236      }                                                 \
 237    else                                                \
 238      {                                                 \
 239        _nl = X##_f << (_FP_WFRACBITS_##fs - 1);        \
 240        _nh = X##_f >> (_FP_WFRACXBITS_##fs + 1);       \
 241      }                                                 \
 242    udiv_qrnnd(_q, _r, _nh, _nl, Y##_f);                \
 243    R##_f = _q | (_r != 0);                             \
 244  } while (0)
 245  
 246  
 247/*
 248 * Square root algorithms:
 249 * We have just one right now, maybe Newton approximation
 250 * should be added for those machines where division is fast.
 251 */
 252 
 253#define _FP_SQRT_MEAT_1(R, S, T, X, q)                  \
 254  do {                                                  \
 255    while (q != _FP_WORK_ROUND)                         \
 256      {                                                 \
 257        T##_f = S##_f + q;                              \
 258        if (T##_f <= X##_f)                             \
 259          {                                             \
 260            S##_f = T##_f + q;                          \
 261            X##_f -= T##_f;                             \
 262            R##_f += q;                                 \
 263          }                                             \
 264        _FP_FRAC_SLL_1(X, 1);                           \
 265        q >>= 1;                                        \
 266      }                                                 \
 267    if (X##_f)                                          \
 268      {                                                 \
 269        if (S##_f < X##_f)                              \
 270          R##_f |= _FP_WORK_ROUND;                      \
 271        R##_f |= _FP_WORK_STICKY;                       \
 272      }                                                 \
 273  } while (0)
 274
 275/*
 276 * Assembly/disassembly for converting to/from integral types.  
 277 * No shifting or overflow handled here.
 278 */
 279
 280#define _FP_FRAC_ASSEMBLE_1(r, X, rsize)        (r = X##_f)
 281#define _FP_FRAC_DISASSEMBLE_1(X, r, rsize)     (X##_f = r)
 282
 283
 284/*
 285 * Convert FP values between word sizes
 286 */
 287
 288#define _FP_FRAC_CONV_1_1(dfs, sfs, D, S)                               \
 289  do {                                                                  \
 290    D##_f = S##_f;                                                      \
 291    if (_FP_WFRACBITS_##sfs > _FP_WFRACBITS_##dfs)                      \
 292      {                                                                 \
 293        if (S##_c != FP_CLS_NAN)                                        \
 294          _FP_FRAC_SRS_1(D, (_FP_WFRACBITS_##sfs-_FP_WFRACBITS_##dfs),  \
 295                         _FP_WFRACBITS_##sfs);                          \
 296        else                                                            \
 297          _FP_FRAC_SRL_1(D, (_FP_WFRACBITS_##sfs-_FP_WFRACBITS_##dfs)); \
 298      }                                                                 \
 299    else                                                                \
 300      D##_f <<= _FP_WFRACBITS_##dfs - _FP_WFRACBITS_##sfs;              \
 301  } while (0)
 302
 303#endif /* __MATH_EMU_OP_1_H__ */
 304
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