gcc/config/cris/arit.c

/* Signed and unsigned multiplication and division and modulus for CRIS.
   Contributed by Axis Communications.
   Written by Hans-Peter Nilsson <hp@axis.se>, c:a 1992.

   Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.

In addition to the permissions in the GNU General Public License, the
Free Software Foundation gives you unlimited permission to link the
compiled version of this file with other programs, and to distribute
those programs without any restriction coming from the use of this
file.  (The General Public License restrictions do apply in other
respects; for example, they cover modification of the file, and
distribution when not linked into another program.)

This file is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.

   As a special exception, if you link this library with files, some of
   which are compiled with GCC, this library does not by itself cause
   the resulting object or executable to be covered by the GNU General
   Public License.
   This exception does not however invalidate any other reasons why
   the executable file or object might be covered by the GNU General
   Public License.  */


/* Note that we provide prototypes for all "const" functions, to attach
   the const attribute.  This is necessary in 2.7.2 - adding the
   attribute to the function *definition* is a syntax error.
    This did not work with e.g. 2.1; back then, the return type had to
   be "const".  */

#include "config.h"

#if defined (__CRIS_arch_version) && __CRIS_arch_version >= 3
#define LZ(v) __extension__ \
 ({ int tmp_; __asm__ ("lz %1,%0" : "=r" (tmp_) : "r" (v)); tmp_; })
#endif


#if defined (L_udivsi3) || defined (L_divsi3) || defined (L_umodsi3) \
    || defined (L_modsi3)
/* Result type of divmod worker function.  */
struct quot_rem
 {
   long quot;
   long rem;
 };

/* This is the worker function for div and mod.  It is inlined into the
   respective library function.  */
static __inline__ struct quot_rem
do_31div (unsigned long a, unsigned long b)
     __attribute__ ((__const__, __always_inline__));

static __inline__ struct quot_rem
do_31div (unsigned long a, unsigned long b)
{
  /* Adjust operands and result if a is 31 bits.  */
  long extra = 0;
  int quot_digits = 0;

  if (b == 0)
    {
      struct quot_rem ret;
      ret.quot = 0xffffffff;
      ret.rem = 0xffffffff;
      return ret;
    }

  if (a < b)
    return (struct quot_rem) { 0, a };

#ifdef LZ
  if (b <= a)
    {
      quot_digits = LZ (b) - LZ (a);
      quot_digits += (a >= (b << quot_digits));
      b <<= quot_digits;
    }
#else
  while (b <= a)
    {
      b <<= 1;
      quot_digits++;
    }
#endif

  /* Is a 31 bits?  Note that bit 31 is handled by the caller.  */
  if (a & 0x40000000)
    {
      /* Then make b:s highest bit max 0x40000000, because it must have
	 been 0x80000000 to be 1 bit higher than a.  */
      b >>= 1;

      /* Adjust a to be maximum 0x3fffffff, i.e. two upper bits zero.  */
      if (a >= b)
	{
	  a -= b;
	  extra = 1 << (quot_digits - 1);
	}
      else
	{
	  a -= b >> 1;

	  /* Remember that we adjusted a by subtracting b * 2 ** Something.  */
	  extra = 1 << quot_digits;
	}

      /* The number of quotient digits will be one less, because
	 we just adjusted b.  */
      quot_digits--;
    }

  /* Now do the division part.  */

  /* Subtract b and add ones to the right when a >= b
     i.e. "a - (b - 1) == (a - b) + 1".  */
  b--;

#define DS __asm__ ("dstep %2,%0" : "=r" (a) : "0" (a), "r" (b))

  switch (quot_digits)
    {
    case 32: DS; case 31: DS; case 30: DS; case 29: DS;
    case 28: DS; case 27: DS; case 26: DS; case 25: DS;
    case 24: DS; case 23: DS; case 22: DS; case 21: DS;
    case 20: DS; case 19: DS; case 18: DS; case 17: DS;
    case 16: DS; case 15: DS; case 14: DS; case 13: DS;
    case 12: DS; case 11: DS; case 10: DS; case 9: DS;
    case 8: DS; case 7: DS; case 6: DS; case 5: DS;
    case 4: DS; case 3: DS; case 2: DS; case 1: DS;
    case 0:;
    }

  {
    struct quot_rem ret;
    ret.quot = (a & ((1 << quot_digits) - 1)) + extra;
    ret.rem = a >> quot_digits;
    return ret;
  }
}

/* Note that unsigned and signed division both build when L_divsi3, but
   the unsigned variant is then inlined, as with do_31div above.  */
#if defined (L_udivsi3) || defined (L_divsi3)
#ifndef L_udivsi3
static __inline__
#endif
unsigned long
__Udiv (unsigned long a, unsigned long b)
     __attribute__ ((__const__, __always_inline__));

#ifndef L_udivsi3
static __inline__
#endif
unsigned long
__Udiv (unsigned long a, unsigned long b)
{
  long extra = 0;

  /* Adjust operands and result, if a and/or b is 32 bits.  */
  /* Effectively: b & 0x80000000.  */
  if ((long) b < 0)
    return a >= b;

  /* Effectively: a & 0x80000000.  */
  if ((long) a < 0)
    {
      int tmp = 0;

      if (b == 0)
	return 0xffffffff;
#ifdef LZ
      tmp = LZ (b);
#else
      for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--)
	;

      tmp = 31 - tmp;
#endif

      if ((b << tmp) > a)
	{
	  extra = 1 << (tmp-1);
	  a -= b << (tmp - 1);
	}
      else
	{
	  extra = 1 << tmp;
	  a -= b << tmp;
	}
    }

  return do_31div (a, b).quot+extra;
}


#ifdef L_divsi3
long
__Div (long a, long b) __attribute__ ((__const__));

long
__Div (long a, long b)
{
  long sign;
  long result;

  /* Do *not* call do_31div since abs (-2147483648) == 2147483648
     <=> abs (-0x80000000) == 0x80000000
     which is still 32 bits.  */

  sign = a ^ b;
  result = __Udiv (__builtin_labs (a), __builtin_labs (b));

  return  (sign < 0) ? -result : result;
}
#endif /* L_divsi3 */
#endif /* L_udivsi3 || L_divsi3 */


/* Note that unsigned and signed modulus both build when L_modsi3, but
   then the unsigned variant is inlined, as with do_31div above.  */
#if defined (L_umodsi3) || defined (L_modsi3)
#ifndef L_umodsi3
static __inline__
#endif
unsigned long
__Umod (unsigned long a, unsigned long b)
     __attribute__ ((__const__, __always_inline__));

#ifndef L_umodsi3
static __inline__
#endif
unsigned long
__Umod (unsigned long a, unsigned long b)
{
  /* Adjust operands and result if a and/or b is 32 bits.  */
  if ((long) b < 0)
    return a >= b ? a - b : a;

  if ((long) a < 0)
    {
      int tmp = 0;

      if (b == 0)
	return a;
#ifdef LZ
      tmp = LZ (b);
#else
      for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--)
	;
      tmp = 31 - tmp;
#endif

      if ((b << tmp) > a)
	{
	  a -= b << (tmp - 1);
	}
      else
	{
	  a -= b << tmp;
	}
    }

  return do_31div (a, b).rem;
}

#ifdef L_modsi3
long
__Mod (long a, long b) __attribute__ ((__const__));

long
__Mod (long a, long b)
{
  long	result;

  result = __Umod (__builtin_labs (a), __builtin_labs (b));

  return (a < 0) ? -result : result;
}
#endif /* L_modsi3 */
#endif /* L_umodsi3 || L_modsi3 */
#endif /* L_udivsi3 || L_divsi3 || L_umodsi3 || L_modsi3 */

/*
 * Local variables:
 * eval: (c-set-style "gnu")
 * indent-tabs-mode: t
 * End:
 */