soft-fp/op-1.h

   1 /* Software floating-point emulation.
   2    Basic one-word fraction declaration and manipulation.
   3    Copyright (C) 1997,1998,1999,2006 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 Lesser General Public
  12    License as published by the Free Software Foundation; either
  13    version 2.1 of the License, or (at your option) any later version.
  14
  15    In addition to the permissions in the GNU Lesser General Public
  16    License, the Free Software Foundation gives you unlimited
  17    permission to link the compiled version of this file into
  18    combinations with other programs, and to distribute those
  19    combinations without any restriction coming from the use of this
  20    file.  (The Lesser General Public License restrictions do apply in
  21    other respects; for example, they cover modification of the file,
  22    and distribution when not linked into a combine executable.)
  23
  24    The GNU C Library is distributed in the hope that it will be useful,
  25    but WITHOUT ANY WARRANTY; without even the implied warranty of
  26    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  27    Lesser General Public License for more details.
  28
  29    You should have received a copy of the GNU Lesser General Public
  30    License along with the GNU C Library; if not, write to the Free
  31    Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
  32    MA 02110-1301, USA.  */
  33
  34 #define _FP_FRAC_DECL_1(X)      _FP_W_TYPE X##_f
  35 #define _FP_FRAC_COPY_1(D,S)    (D##_f = S##_f)
  36 #define _FP_FRAC_SET_1(X,I)     (X##_f = I)
  37 #define _FP_FRAC_HIGH_1(X)      (X##_f)
  38 #define _FP_FRAC_LOW_1(X)       (X##_f)
  39 #define _FP_FRAC_WORD_1(X,w)    (X##_f)
  40
  41 #define _FP_FRAC_ADDI_1(X,I)    (X##_f += I)
  42 #define _FP_FRAC_SLL_1(X,N)                     \
  43   do {                                          \
  44     if (__builtin_constant_p(N) && (N) == 1)    \
  45       X##_f += X##_f;                           \
  46     else                                        \
  47       X##_f <<= (N);                            \
  48   } while (0)
  49 #define _FP_FRAC_SRL_1(X,N)     (X##_f >>= N)
  50
  51 /* Right shift with sticky-lsb.  */
  52 #define _FP_FRAC_SRST_1(X,S,N,sz)       __FP_FRAC_SRST_1(X##_f, S, N, sz)
  53 #define _FP_FRAC_SRS_1(X,N,sz)  __FP_FRAC_SRS_1(X##_f, N, sz)
  54
  55 #define __FP_FRAC_SRST_1(X,S,N,sz)                      \
  56 do {                                                    \
  57   S = (__builtin_constant_p(N) && (N) == 1              \
  58        ? X & 1 : (X << (_FP_W_TYPE_SIZE - (N))) != 0);  \
  59   X = X >> (N);                                         \
  60 } while (0)
  61
  62 #define __FP_FRAC_SRS_1(X,N,sz)                                         \
  63    (X = (X >> (N) | (__builtin_constant_p(N) && (N) == 1                \
  64                      ? X & 1 : (X << (_FP_W_TYPE_SIZE - (N))) != 0)))
  65
  66 #define _FP_FRAC_ADD_1(R,X,Y)   (R##_f = X##_f + Y##_f)
  67 #define _FP_FRAC_SUB_1(R,X,Y)   (R##_f = X##_f - Y##_f)
  68 #define _FP_FRAC_DEC_1(X,Y)     (X##_f -= Y##_f)
  69 #define _FP_FRAC_CLZ_1(z, X)    __FP_CLZ(z, X##_f)
  70
  71 /* Predicates */
  72 #define _FP_FRAC_NEGP_1(X)      ((_FP_WS_TYPE)X##_f < 0)
  73 #define _FP_FRAC_ZEROP_1(X)     (X##_f == 0)
  74 #define _FP_FRAC_OVERP_1(fs,X)  (X##_f & _FP_OVERFLOW_##fs)
  75 #define _FP_FRAC_CLEAR_OVERP_1(fs,X)    (X##_f &= ~_FP_OVERFLOW_##fs)
  76 #define _FP_FRAC_EQ_1(X, Y)     (X##_f == Y##_f)
  77 #define _FP_FRAC_GE_1(X, Y)     (X##_f >= Y##_f)
  78 #define _FP_FRAC_GT_1(X, Y)     (X##_f > Y##_f)
  79
  80 #define _FP_ZEROFRAC_1          0
  81 #define _FP_MINFRAC_1           1
  82 #define _FP_MAXFRAC_1           (~(_FP_WS_TYPE)0)
  83
  84 /*
  85  * Unpack the raw bits of a native fp value.  Do not classify or
  86  * normalize the data.
  87  */
  88
  89 #define _FP_UNPACK_RAW_1(fs, X, val)                            \
  90   do {                                                          \
  91     union _FP_UNION_##fs _flo; _flo.flt = (val);                \
  92                                                                 \
  93     X##_f = _flo.bits.frac;                                     \
  94     X##_e = _flo.bits.exp;                                      \
  95     X##_s = _flo.bits.sign;                                     \
  96   } while (0)
  97
  98 #define _FP_UNPACK_RAW_1_P(fs, X, val)                          \
  99   do {                                                          \
 100     union _FP_UNION_##fs *_flo =                                \
 101       (union _FP_UNION_##fs *)(val);                            \
 102                                                                 \
 103     X##_f = _flo->bits.frac;                                    \
 104     X##_e = _flo->bits.exp;                                     \
 105     X##_s = _flo->bits.sign;                                    \
 106   } while (0)
 107
 108 /*
 109  * Repack the raw bits of a native fp value.
 110  */
 111
 112 #define _FP_PACK_RAW_1(fs, val, X)                              \
 113   do {                                                          \
 114     union _FP_UNION_##fs _flo;                                  \
 115                                                                 \
 116     _flo.bits.frac = X##_f;                                     \
 117     _flo.bits.exp  = X##_e;                                     \
 118     _flo.bits.sign = X##_s;                                     \
 119                                                                 \
 120     (val) = _flo.flt;                                           \
 121   } while (0)
 122
 123 #define _FP_PACK_RAW_1_P(fs, val, X)                            \
 124   do {                                                          \
 125     union _FP_UNION_##fs *_flo =                                \
 126       (union _FP_UNION_##fs *)(val);                            \
 127                                                                 \
 128     _flo->bits.frac = X##_f;                                    \
 129     _flo->bits.exp  = X##_e;                                    \
 130     _flo->bits.sign = X##_s;                                    \
 131   } while (0)
 132
 133
 134 /*
 135  * Multiplication algorithms:
 136  */
 137
 138 /* Basic.  Assuming the host word size is >= 2*FRACBITS, we can do the
 139    multiplication immediately.  */
 140
 141 #define _FP_MUL_MEAT_1_imm(wfracbits, R, X, Y)                          \
 142   do {                                                                  \
 143     R##_f = X##_f * Y##_f;                                              \
 144     /* Normalize since we know where the msb of the multiplicands       \
 145        were (bit B), we know that the msb of the of the product is      \
 146        at either 2B or 2B-1.  */                                        \
 147     _FP_FRAC_SRS_1(R, wfracbits-1, 2*wfracbits);                        \
 148   } while (0)
 149
 150 /* Given a 1W * 1W => 2W primitive, do the extended multiplication.  */
 151
 152 #define _FP_MUL_MEAT_1_wide(wfracbits, R, X, Y, doit)                   \
 153   do {                                                                  \
 154     _FP_W_TYPE _Z_f0, _Z_f1;                                            \
 155     doit(_Z_f1, _Z_f0, X##_f, Y##_f);                                   \
 156     /* Normalize since we know where the msb of the multiplicands       \
 157        were (bit B), we know that the msb of the of the product is      \
 158        at either 2B or 2B-1.  */                                        \
 159     _FP_FRAC_SRS_2(_Z, wfracbits-1, 2*wfracbits);                       \
 160     R##_f = _Z_f0;                                                      \
 161   } while (0)
 162
 163 /* Finally, a simple widening multiply algorithm.  What fun!  */
 164
 165 #define _FP_MUL_MEAT_1_hard(wfracbits, R, X, Y)                         \
 166   do {                                                                  \
 167     _FP_W_TYPE _xh, _xl, _yh, _yl, _z_f0, _z_f1, _a_f0, _a_f1;          \
 168                                                                         \
 169     /* split the words in half */                                       \
 170     _xh = X##_f >> (_FP_W_TYPE_SIZE/2);                                 \
 171     _xl = X##_f & (((_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2)) - 1);         \
 172     _yh = Y##_f >> (_FP_W_TYPE_SIZE/2);                                 \
 173     _yl = Y##_f & (((_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2)) - 1);         \
 174                                                                         \
 175     /* multiply the pieces */                                           \
 176     _z_f0 = _xl * _yl;                                                  \
 177     _a_f0 = _xh * _yl;                                                  \
 178     _a_f1 = _xl * _yh;                                                  \
 179     _z_f1 = _xh * _yh;                                                  \
 180                                                                         \
 181     /* reassemble into two full words */                                \
 182     if ((_a_f0 += _a_f1) < _a_f1)                                       \
 183       _z_f1 += (_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2);                    \
 184     _a_f1 = _a_f0 >> (_FP_W_TYPE_SIZE/2);                               \
 185     _a_f0 = _a_f0 << (_FP_W_TYPE_SIZE/2);                               \
 186     _FP_FRAC_ADD_2(_z, _z, _a);                                         \
 187                                                                         \
 188     /* normalize */                                                     \
 189     _FP_FRAC_SRS_2(_z, wfracbits - 1, 2*wfracbits);                     \
 190     R##_f = _z_f0;                                                      \
 191   } while (0)
 192
 193
 194 /*
 195  * Division algorithms:
 196  */
 197
 198 /* Basic.  Assuming the host word size is >= 2*FRACBITS, we can do the
 199    division immediately.  Give this macro either _FP_DIV_HELP_imm for
 200    C primitives or _FP_DIV_HELP_ldiv for the ISO function.  Which you
 201    choose will depend on what the compiler does with divrem4.  */
 202
 203 #define _FP_DIV_MEAT_1_imm(fs, R, X, Y, doit)           \
 204   do {                                                  \
 205     _FP_W_TYPE _q, _r;                                  \
 206     X##_f <<= (X##_f < Y##_f                            \
 207                ? R##_e--, _FP_WFRACBITS_##fs            \
 208                : _FP_WFRACBITS_##fs - 1);               \
 209     doit(_q, _r, X##_f, Y##_f);                         \
 210     R##_f = _q | (_r != 0);                             \
 211   } while (0)
 212
 213 /* GCC's longlong.h defines a 2W / 1W => (1W,1W) primitive udiv_qrnnd
 214    that may be useful in this situation.  This first is for a primitive
 215    that requires normalization, the second for one that does not.  Look
 216    for UDIV_NEEDS_NORMALIZATION to tell which your machine needs.  */
 217
 218 #define _FP_DIV_MEAT_1_udiv_norm(fs, R, X, Y)                           \
 219   do {                                                                  \
 220     _FP_W_TYPE _nh, _nl, _q, _r, _y;                                    \
 221                                                                         \
 222     /* Normalize Y -- i.e. make the most significant bit set.  */       \
 223     _y = Y##_f << _FP_WFRACXBITS_##fs;                                  \
 224                                                                         \
 225     /* Shift X op correspondingly high, that is, up one full word.  */  \
 226     if (X##_f < Y##_f)                                                  \
 227       {                                                                 \
 228         R##_e--;                                                        \
 229         _nl = 0;                                                        \
 230         _nh = X##_f;                                                    \
 231       }                                                                 \
 232     else                                                                \
 233       {                                                                 \
 234         _nl = X##_f << (_FP_W_TYPE_SIZE - 1);                           \
 235         _nh = X##_f >> 1;                                               \
 236       }                                                                 \
 237                                                                         \
 238     udiv_qrnnd(_q, _r, _nh, _nl, _y);                                   \
 239     R##_f = _q | (_r != 0);                                             \
 240   } while (0)
 241
 242 #define _FP_DIV_MEAT_1_udiv(fs, R, X, Y)                \
 243   do {                                                  \
 244     _FP_W_TYPE _nh, _nl, _q, _r;                        \
 245     if (X##_f < Y##_f)                                  \
 246       {                                                 \
 247         R##_e--;                                        \
 248         _nl = X##_f << _FP_WFRACBITS_##fs;              \
 249         _nh = X##_f >> _FP_WFRACXBITS_##fs;             \
 250       }                                                 \
 251     else                                                \
 252       {                                                 \
 253         _nl = X##_f << (_FP_WFRACBITS_##fs - 1);        \
 254         _nh = X##_f >> (_FP_WFRACXBITS_##fs + 1);       \
 255       }                                                 \
 256     udiv_qrnnd(_q, _r, _nh, _nl, Y##_f);                \
 257     R##_f = _q | (_r != 0);                             \
 258   } while (0)
 259
 260
 261 /*
 262  * Square root algorithms:
 263  * We have just one right now, maybe Newton approximation
 264  * should be added for those machines where division is fast.
 265  */
 266
 267 #define _FP_SQRT_MEAT_1(R, S, T, X, q)                  \
 268   do {                                                  \
 269     while (q != _FP_WORK_ROUND)                         \
 270       {                                                 \
 271         T##_f = S##_f + q;                              \
 272         if (T##_f <= X##_f)                             \
 273           {                                             \
 274             S##_f = T##_f + q;                          \
 275             X##_f -= T##_f;                             \
 276             R##_f += q;                                 \
 277           }                                             \
 278         _FP_FRAC_SLL_1(X, 1);                           \
 279         q >>= 1;                                        \
 280       }                                                 \
 281     if (X##_f)                                          \
 282       {                                                 \
 283         if (S##_f < X##_f)                              \
 284           R##_f |= _FP_WORK_ROUND;                      \
 285         R##_f |= _FP_WORK_STICKY;                       \
 286       }                                                 \
 287   } while (0)
 288
 289 /*
 290  * Assembly/disassembly for converting to/from integral types.
 291  * No shifting or overflow handled here.
 292  */
 293
 294 #define _FP_FRAC_ASSEMBLE_1(r, X, rsize)        (r = X##_f)
 295 #define _FP_FRAC_DISASSEMBLE_1(X, r, rsize)     (X##_f = r)
 296
 297
 298 /*
 299  * Convert FP values between word sizes
 300  */
 301
 302 #define _FP_FRAC_COPY_1_1(D, S)         (D##_f = S##_f)