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