gcc/config/cris/arit.c

   1 /* Signed and unsigned multiplication and division and modulus for CRIS.
   2    Contributed by Axis Communications.
   3    Written by Hans-Peter Nilsson <hp@axis.se>, c:a 1992.
   4
   5    Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
   6
   7 This file is part of GCC.
   8
   9 GCC is free software; you can redistribute it and/or modify it
  10 under the terms of the GNU General Public License as published by the
  11 Free Software Foundation; either version 2, or (at your option) any
  12 later version.
  13
  14 In addition to the permissions in the GNU General Public License, the
  15 Free Software Foundation gives you unlimited permission to link the
  16 compiled version of this file with other programs, and to distribute
  17 those programs without any restriction coming from the use of this
  18 file.  (The General Public License restrictions do apply in other
  19 respects; for example, they cover modification of the file, and
  20 distribution when not linked into another program.)
  21
  22 This file is distributed in the hope that it will be useful, but
  23 WITHOUT ANY WARRANTY; without even the implied warranty of
  24 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  25 General Public License for more details.
  26
  27 You should have received a copy of the GNU General Public License
  28 along with this program; see the file COPYING.  If not, write to
  29 the Free Software Foundation, 59 Temple Place - Suite 330,
  30 Boston, MA 02111-1307, USA.
  31
  32    As a special exception, if you link this library with files, some of
  33    which are compiled with GCC, this library does not by itself cause
  34    the resulting object or executable to be covered by the GNU General
  35    Public License.
  36    This exception does not however invalidate any other reasons why
  37    the executable file or object might be covered by the GNU General
  38    Public License.  */
  39
  40
  41 /* Note that we provide prototypes for all "const" functions, to attach
  42    the const attribute.  This is necessary in 2.7.2 - adding the
  43    attribute to the function *definition* is a syntax error.
  44     This did not work with e.g. 2.1; back then, the return type had to
  45    be "const".  */
  46
  47 #include "config.h"
  48
  49 #if defined (__CRIS_arch_version) && __CRIS_arch_version >= 3
  50 #define LZ(v) __extension__ \
  51  ({ int tmp_; __asm__ ("lz %1,%0" : "=r" (tmp_) : "r" (v)); tmp_; })
  52 #endif
  53
  54
  55 #if defined (L_udivsi3) || defined (L_divsi3) || defined (L_umodsi3) \
  56     || defined (L_modsi3)
  57 /* Result type of divmod worker function.  */
  58 struct quot_rem
  59  {
  60    long quot;
  61    long rem;
  62  };
  63
  64 /* This is the worker function for div and mod.  It is inlined into the
  65    respective library function.  */
  66 static __inline__ struct quot_rem
  67 do_31div (unsigned long a, unsigned long b)
  68      __attribute__ ((__const__, __always_inline__));
  69
  70 static __inline__ struct quot_rem
  71 do_31div (unsigned long a, unsigned long b)
  72 {
  73   /* Adjust operands and result if a is 31 bits.  */
  74   long extra = 0;
  75   int quot_digits = 0;
  76
  77   if (b == 0)
  78     {
  79       struct quot_rem ret;
  80       ret.quot = 0xffffffff;
  81       ret.rem = 0xffffffff;
  82       return ret;
  83     }
  84
  85   if (a < b)
  86     return (struct quot_rem) { 0, a };
  87
  88 #ifdef LZ
  89   if (b <= a)
  90     {
  91       quot_digits = LZ (b) - LZ (a);
  92       quot_digits += (a >= (b << quot_digits));
  93       b <<= quot_digits;
  94     }
  95 #else
  96   while (b <= a)
  97     {
  98       b <<= 1;
  99       quot_digits++;
 100     }
 101 #endif
 102
 103   /* Is a 31 bits?  Note that bit 31 is handled by the caller.  */
 104   if (a & 0x40000000)
 105     {
 106       /* Then make b:s highest bit max 0x40000000, because it must have
 107          been 0x80000000 to be 1 bit higher than a.  */
 108       b >>= 1;
 109
 110       /* Adjust a to be maximum 0x3fffffff, i.e. two upper bits zero.  */
 111       if (a >= b)
 112         {
 113           a -= b;
 114           extra = 1 << (quot_digits - 1);
 115         }
 116       else
 117         {
 118           a -= b >> 1;
 119
 120           /* Remember that we adjusted a by subtracting b * 2 ** Something.  */
 121           extra = 1 << quot_digits;
 122         }
 123
 124       /* The number of quotient digits will be one less, because
 125          we just adjusted b.  */
 126       quot_digits--;
 127     }
 128
 129   /* Now do the division part.  */
 130
 131   /* Subtract b and add ones to the right when a >= b
 132      i.e. "a - (b - 1) == (a - b) + 1".  */
 133   b--;
 134
 135 #define DS __asm__ ("dstep %2,%0" : "=r" (a) : "0" (a), "r" (b))
 136
 137   switch (quot_digits)
 138     {
 139     case 32: DS; case 31: DS; case 30: DS; case 29: DS;
 140     case 28: DS; case 27: DS; case 26: DS; case 25: DS;
 141     case 24: DS; case 23: DS; case 22: DS; case 21: DS;
 142     case 20: DS; case 19: DS; case 18: DS; case 17: DS;
 143     case 16: DS; case 15: DS; case 14: DS; case 13: DS;
 144     case 12: DS; case 11: DS; case 10: DS; case 9: DS;
 145     case 8: DS; case 7: DS; case 6: DS; case 5: DS;
 146     case 4: DS; case 3: DS; case 2: DS; case 1: DS;
 147     case 0:;
 148     }
 149
 150   {
 151     struct quot_rem ret;
 152     ret.quot = (a & ((1 << quot_digits) - 1)) + extra;
 153     ret.rem = a >> quot_digits;
 154     return ret;
 155   }
 156 }
 157
 158 /* Note that unsigned and signed division both build when L_divsi3, but
 159    the unsigned variant is then inlined, as with do_31div above.  */
 160 #if defined (L_udivsi3) || defined (L_divsi3)
 161 #ifndef L_udivsi3
 162 static __inline__
 163 #endif
 164 unsigned long
 165 __Udiv (unsigned long a, unsigned long b)
 166      __attribute__ ((__const__, __always_inline__));
 167
 168 #ifndef L_udivsi3
 169 static __inline__
 170 #endif
 171 unsigned long
 172 __Udiv (unsigned long a, unsigned long b)
 173 {
 174   long extra = 0;
 175
 176   /* Adjust operands and result, if a and/or b is 32 bits.  */
 177   /* Effectively: b & 0x80000000.  */
 178   if ((long) b < 0)
 179     return a >= b;
 180
 181   /* Effectively: a & 0x80000000.  */
 182   if ((long) a < 0)
 183     {
 184       int tmp = 0;
 185
 186       if (b == 0)
 187         return 0xffffffff;
 188 #ifdef LZ
 189       tmp = LZ (b);
 190 #else
 191       for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--)
 192         ;
 193
 194       tmp = 31 - tmp;
 195 #endif
 196
 197       if ((b << tmp) > a)
 198         {
 199           extra = 1 << (tmp-1);
 200           a -= b << (tmp - 1);
 201         }
 202       else
 203         {
 204           extra = 1 << tmp;
 205           a -= b << tmp;
 206         }
 207     }
 208
 209   return do_31div (a, b).quot+extra;
 210 }
 211
 212
 213 #ifdef L_divsi3
 214 long
 215 __Div (long a, long b) __attribute__ ((__const__));
 216
 217 long
 218 __Div (long a, long b)
 219 {
 220   long sign;
 221   long result;
 222
 223   /* Do *not* call do_31div since abs (-2147483648) == 2147483648
 224      <=> abs (-0x80000000) == 0x80000000
 225      which is still 32 bits.  */
 226
 227   sign = a ^ b;
 228   result = __Udiv (__builtin_labs (a), __builtin_labs (b));
 229
 230   return  (sign < 0) ? -result : result;
 231 }
 232 #endif /* L_divsi3 */
 233 #endif /* L_udivsi3 || L_divsi3 */
 234
 235
 236 /* Note that unsigned and signed modulus both build when L_modsi3, but
 237    then the unsigned variant is inlined, as with do_31div above.  */
 238 #if defined (L_umodsi3) || defined (L_modsi3)
 239 #ifndef L_umodsi3
 240 static __inline__
 241 #endif
 242 unsigned long
 243 __Umod (unsigned long a, unsigned long b)
 244      __attribute__ ((__const__, __always_inline__));
 245
 246 #ifndef L_umodsi3
 247 static __inline__
 248 #endif
 249 unsigned long
 250 __Umod (unsigned long a, unsigned long b)
 251 {
 252   /* Adjust operands and result if a and/or b is 32 bits.  */
 253   if ((long) b < 0)
 254     return a >= b ? a - b : a;
 255
 256   if ((long) a < 0)
 257     {
 258       int tmp = 0;
 259
 260       if (b == 0)
 261         return a;
 262 #ifdef LZ
 263       tmp = LZ (b);
 264 #else
 265       for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--)
 266         ;
 267       tmp = 31 - tmp;
 268 #endif
 269
 270       if ((b << tmp) > a)
 271         {
 272           a -= b << (tmp - 1);
 273         }
 274       else
 275         {
 276           a -= b << tmp;
 277         }
 278     }
 279
 280   return do_31div (a, b).rem;
 281 }
 282
 283 #ifdef L_modsi3
 284 long
 285 __Mod (long a, long b) __attribute__ ((__const__));
 286
 287 long
 288 __Mod (long a, long b)
 289 {
 290   long  result;
 291
 292   result = __Umod (__builtin_labs (a), __builtin_labs (b));
 293
 294   return (a < 0) ? -result : result;
 295 }
 296 #endif /* L_modsi3 */
 297 #endif /* L_umodsi3 || L_modsi3 */
 298 #endif /* L_udivsi3 || L_divsi3 || L_umodsi3 || L_modsi3 */
 299
 300 /*
 301  * Local variables:
 302  * eval: (c-set-style "gnu")
 303  * indent-tabs-mode: t
 304  * End:
 305  */