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    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    Lesser General Public License for more details.
  19
  20    You should have received a copy of the GNU Lesser General Public
  21    License along with the GNU C Library; if not, write to the Free
  22    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  23    02111-1307 USA.  */
  24
  25 #define _FP_FRAC_DECL_1(X)      _FP_W_TYPE X##_f
  26 #define _FP_FRAC_COPY_1(D,S)    (D##_f = S##_f)
  27 #define _FP_FRAC_SET_1(X,I)     (X##_f = I)
  28 #define _FP_FRAC_HIGH_1(X)      (X##_f)
  29 #define _FP_FRAC_LOW_1(X)       (X##_f)
  30 #define _FP_FRAC_WORD_1(X,w)    (X##_f)
  31
  32 #define _FP_FRAC_ADDI_1(X,I)    (X##_f += I)
  33 #define _FP_FRAC_SLL_1(X,N)                     \
  34   do {                                          \
  35     if (__builtin_constant_p(N) && (N) == 1)    \
  36       X##_f += X##_f;                           \
  37     else                                        \
  38       X##_f <<= (N);                            \
  39   } while (0)
  40 #define _FP_FRAC_SRL_1(X,N)     (X##_f >>= N)
  41
  42 /* Right shift with sticky-lsb.  */
  43 #define _FP_FRAC_SRST_1(X,S,N,sz)       __FP_FRAC_SRST_1(X##_f, S, N, sz)
  44 #define _FP_FRAC_SRS_1(X,N,sz)  __FP_FRAC_SRS_1(X##_f, N, sz)
  45
  46 #define __FP_FRAC_SRST_1(X,S,N,sz)                      \
  47 do {                                                    \
  48   S = (__builtin_constant_p(N) && (N) == 1              \
  49        ? X & 1 : (X << (_FP_W_TYPE_SIZE - (N))) != 0);  \
  50   X = X >> (N);                                         \
  51 } while (0)
  52
  53 #define __FP_FRAC_SRS_1(X,N,sz)                                         \
  54    (X = (X >> (N) | (__builtin_constant_p(N) && (N) == 1                \
  55                      ? X & 1 : (X << (_FP_W_TYPE_SIZE - (N))) != 0)))
  56
  57 #define _FP_FRAC_ADD_1(R,X,Y)   (R##_f = X##_f + Y##_f)
  58 #define _FP_FRAC_SUB_1(R,X,Y)   (R##_f = X##_f - Y##_f)
  59 #define _FP_FRAC_DEC_1(X,Y)     (X##_f -= Y##_f)
  60 #define _FP_FRAC_CLZ_1(z, X)    __FP_CLZ(z, X##_f)
  61
  62 /* Predicates */
  63 #define _FP_FRAC_NEGP_1(X)      ((_FP_WS_TYPE)X##_f < 0)
  64 #define _FP_FRAC_ZEROP_1(X)     (X##_f == 0)
  65 #define _FP_FRAC_OVERP_1(fs,X)  (X##_f & _FP_OVERFLOW_##fs)
  66 #define _FP_FRAC_CLEAR_OVERP_1(fs,X)    (X##_f &= ~_FP_OVERFLOW_##fs)
  67 #define _FP_FRAC_EQ_1(X, Y)     (X##_f == Y##_f)
  68 #define _FP_FRAC_GE_1(X, Y)     (X##_f >= Y##_f)
  69 #define _FP_FRAC_GT_1(X, Y)     (X##_f > Y##_f)
  70
  71 #define _FP_ZEROFRAC_1          0
  72 #define _FP_MINFRAC_1           1
  73 #define _FP_MAXFRAC_1           (~(_FP_WS_TYPE)0)
  74
  75 /*
  76  * Unpack the raw bits of a native fp value.  Do not classify or
  77  * normalize the data.
  78  */
  79
  80 #define _FP_UNPACK_RAW_1(fs, X, val)                            \
  81   do {                                                          \
  82     union _FP_UNION_##fs _flo; _flo.flt = (val);                \
  83                                                                 \
  84     X##_f = _flo.bits.frac;                                     \
  85     X##_e = _flo.bits.exp;                                      \
  86     X##_s = _flo.bits.sign;                                     \
  87   } while (0)
  88
  89 #define _FP_UNPACK_RAW_1_P(fs, X, val)                          \
  90   do {                                                          \
  91     union _FP_UNION_##fs *_flo =                                \
  92       (union _FP_UNION_##fs *)(val);                            \
  93                                                                 \
  94     X##_f = _flo->bits.frac;                                    \
  95     X##_e = _flo->bits.exp;                                     \
  96     X##_s = _flo->bits.sign;                                    \
  97   } while (0)
  98
  99 /*
 100  * Repack the raw bits of a native fp value.
 101  */
 102
 103 #define _FP_PACK_RAW_1(fs, val, X)                              \
 104   do {                                                          \
 105     union _FP_UNION_##fs _flo;                                  \
 106                                                                 \
 107     _flo.bits.frac = X##_f;                                     \
 108     _flo.bits.exp  = X##_e;                                     \
 109     _flo.bits.sign = X##_s;                                     \
 110                                                                 \
 111     (val) = _flo.flt;                                           \
 112   } while (0)
 113
 114 #define _FP_PACK_RAW_1_P(fs, val, X)                            \
 115   do {                                                          \
 116     union _FP_UNION_##fs *_flo =                                \
 117       (union _FP_UNION_##fs *)(val);                            \
 118                                                                 \
 119     _flo->bits.frac = X##_f;                                    \
 120     _flo->bits.exp  = X##_e;                                    \
 121     _flo->bits.sign = X##_s;                                    \
 122   } while (0)
 123
 124
 125 /*
 126  * Multiplication algorithms:
 127  */
 128
 129 /* Basic.  Assuming the host word size is >= 2*FRACBITS, we can do the
 130    multiplication immediately.  */
 131
 132 #define _FP_MUL_MEAT_1_imm(wfracbits, R, X, Y)                          \
 133   do {                                                                  \
 134     R##_f = X##_f * Y##_f;                                              \
 135     /* Normalize since we know where the msb of the multiplicands       \
 136        were (bit B), we know that the msb of the of the product is      \
 137        at either 2B or 2B-1.  */                                        \
 138     _FP_FRAC_SRS_1(R, wfracbits-1, 2*wfracbits);                        \
 139   } while (0)
 140
 141 /* Given a 1W * 1W => 2W primitive, do the extended multiplication.  */
 142
 143 #define _FP_MUL_MEAT_1_wide(wfracbits, R, X, Y, doit)                   \
 144   do {                                                                  \
 145     _FP_W_TYPE _Z_f0, _Z_f1;                                            \
 146     doit(_Z_f1, _Z_f0, X##_f, Y##_f);                                   \
 147     /* Normalize since we know where the msb of the multiplicands       \
 148        were (bit B), we know that the msb of the of the product is      \
 149        at either 2B or 2B-1.  */                                        \
 150     _FP_FRAC_SRS_2(_Z, wfracbits-1, 2*wfracbits);                       \
 151     R##_f = _Z_f0;                                                      \
 152   } while (0)
 153
 154 /* Finally, a simple widening multiply algorithm.  What fun!  */
 155
 156 #define _FP_MUL_MEAT_1_hard(wfracbits, R, X, Y)                         \
 157   do {                                                                  \
 158     _FP_W_TYPE _xh, _xl, _yh, _yl, _z_f0, _z_f1, _a_f0, _a_f1;          \
 159                                                                         \
 160     /* split the words in half */                                       \
 161     _xh = X##_f >> (_FP_W_TYPE_SIZE/2);                                 \
 162     _xl = X##_f & (((_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2)) - 1);         \
 163     _yh = Y##_f >> (_FP_W_TYPE_SIZE/2);                                 \
 164     _yl = Y##_f & (((_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2)) - 1);         \
 165                                                                         \
 166     /* multiply the pieces */                                           \
 167     _z_f0 = _xl * _yl;                                                  \
 168     _a_f0 = _xh * _yl;                                                  \
 169     _a_f1 = _xl * _yh;                                                  \
 170     _z_f1 = _xh * _yh;                                                  \
 171                                                                         \
 172     /* reassemble into two full words */                                \
 173     if ((_a_f0 += _a_f1) < _a_f1)                                       \
 174       _z_f1 += (_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2);                    \
 175     _a_f1 = _a_f0 >> (_FP_W_TYPE_SIZE/2);                               \
 176     _a_f0 = _a_f0 << (_FP_W_TYPE_SIZE/2);                               \
 177     _FP_FRAC_ADD_2(_z, _z, _a);                                         \
 178                                                                         \
 179     /* normalize */                                                     \
 180     _FP_FRAC_SRS_2(_z, wfracbits - 1, 2*wfracbits);                     \
 181     R##_f = _z_f0;                                                      \
 182   } while (0)
 183
 184
 185 /*
 186  * Division algorithms:
 187  */
 188
 189 /* Basic.  Assuming the host word size is >= 2*FRACBITS, we can do the
 190    division immediately.  Give this macro either _FP_DIV_HELP_imm for
 191    C primitives or _FP_DIV_HELP_ldiv for the ISO function.  Which you
 192    choose will depend on what the compiler does with divrem4.  */
 193
 194 #define _FP_DIV_MEAT_1_imm(fs, R, X, Y, doit)           \
 195   do {                                                  \
 196     _FP_W_TYPE _q, _r;                                  \
 197     X##_f <<= (X##_f < Y##_f                            \
 198                ? R##_e--, _FP_WFRACBITS_##fs            \
 199                : _FP_WFRACBITS_##fs - 1);               \
 200     doit(_q, _r, X##_f, Y##_f);                         \
 201     R##_f = _q | (_r != 0);                             \
 202   } while (0)
 203
 204 /* GCC's longlong.h defines a 2W / 1W => (1W,1W) primitive udiv_qrnnd
 205    that may be useful in this situation.  This first is for a primitive
 206    that requires normalization, the second for one that does not.  Look
 207    for UDIV_NEEDS_NORMALIZATION to tell which your machine needs.  */
 208
 209 #define _FP_DIV_MEAT_1_udiv_norm(fs, R, X, Y)                           \
 210   do {                                                                  \
 211     _FP_W_TYPE _nh, _nl, _q, _r, _y;                                    \
 212                                                                         \
 213     /* Normalize Y -- i.e. make the most significant bit set.  */       \
 214     _y = Y##_f << _FP_WFRACXBITS_##fs;                                  \
 215                                                                         \
 216     /* Shift X op correspondingly high, that is, up one full word.  */  \
 217     if (X##_f < Y##_f)                                                  \
 218       {                                                                 \
 219         R##_e--;                                                        \
 220         _nl = 0;                                                        \
 221         _nh = X##_f;                                                    \
 222       }                                                                 \
 223     else                                                                \
 224       {                                                                 \
 225         _nl = X##_f << (_FP_W_TYPE_SIZE - 1);                           \
 226         _nh = X##_f >> 1;                                               \
 227       }                                                                 \
 228                                                                         \
 229     udiv_qrnnd(_q, _r, _nh, _nl, _y);                                   \
 230     R##_f = _q | (_r != 0);                                             \
 231   } while (0)
 232
 233 #define _FP_DIV_MEAT_1_udiv(fs, R, X, Y)                \
 234   do {                                                  \
 235     _FP_W_TYPE _nh, _nl, _q, _r;                        \
 236     if (X##_f < Y##_f)                                  \
 237       {                                                 \
 238         R##_e--;                                        \
 239         _nl = X##_f << _FP_WFRACBITS_##fs;              \
 240         _nh = X##_f >> _FP_WFRACXBITS_##fs;             \
 241       }                                                 \
 242     else                                                \
 243       {                                                 \
 244         _nl = X##_f << (_FP_WFRACBITS_##fs - 1);        \
 245         _nh = X##_f >> (_FP_WFRACXBITS_##fs + 1);       \
 246       }                                                 \
 247     udiv_qrnnd(_q, _r, _nh, _nl, Y##_f);                \
 248     R##_f = _q | (_r != 0);                             \
 249   } while (0)
 250
 251
 252 /*
 253  * Square root algorithms:
 254  * We have just one right now, maybe Newton approximation
 255  * should be added for those machines where division is fast.
 256  */
 257
 258 #define _FP_SQRT_MEAT_1(R, S, T, X, q)                  \
 259   do {                                                  \
 260     while (q != _FP_WORK_ROUND)                         \
 261       {                                                 \
 262         T##_f = S##_f + q;                              \
 263         if (T##_f <= X##_f)                             \
 264           {                                             \
 265             S##_f = T##_f + q;                          \
 266             X##_f -= T##_f;                             \
 267             R##_f += q;                                 \
 268           }                                             \
 269         _FP_FRAC_SLL_1(X, 1);                           \
 270         q >>= 1;                                        \
 271       }                                                 \
 272     if (X##_f)                                          \
 273       {                                                 \
 274         if (S##_f < X##_f)                              \
 275           R##_f |= _FP_WORK_ROUND;                      \
 276         R##_f |= _FP_WORK_STICKY;                       \
 277       }                                                 \
 278   } while (0)
 279
 280 /*
 281  * Assembly/disassembly for converting to/from integral types.
 282  * No shifting or overflow handled here.
 283  */
 284
 285 #define _FP_FRAC_ASSEMBLE_1(r, X, rsize)        (r = X##_f)
 286 #define _FP_FRAC_DISASSEMBLE_1(X, r, rsize)     (X##_f = r)
 287
 288
 289 /*
 290  * Convert FP values between word sizes
 291  */
 292
 293 #define _FP_FRAC_COPY_1_1(D, S)         (D##_f = S##_f)