es40_float.h

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/* ES40 emulator.
 * Copyright (C) 2007-2008 by Camiel Vanderhoeven
 *
 * Website: www.camicom.com
 * E-mail : camiel@camicom.com
 * 
 * This program 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
 * of the License, or (at your option) any later version.
 * 
 * This program 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; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 * 
 * Although this is not required, the author would appreciate being notified of, 
 * and receiving any modifications you may make to the source code that might serve
 * the general public.
 */

#include <math.h>

//#define DEBUG_FP_CONVERSION 1
//#define DEBUG_FP_LOADSTORE 1
#define FLOAT_IS_IEEE 1

inline double f2host(u64 val)
{
  int s = (val & U64(0x8000000000000000)) ? 1 : 0;
  int e = (int) ((val & U64(0x7ff0000000000000)) >> 52);
  s64 f = (val & U64(0x000fffffffffffff));
  f |= U64(0x0010000000000000);

  double  res;

  if(e == 0)
    res = 0.0;
  else
    res = (s ? -1.0 : 1.0) * pow((double) 2.0, e - 1024) * ((double) f / (double) (s64) U64(0x0020000000000000));

#if defined(DEBUG_FP_CONVERSION)
  printf("f/g->host: %016"LL "x -> %f   \n", val, res);
#endif
  return res;
}

#define g2host  f2host

inline double d2host(u64 val)
{
  int s = (val & U64(0x8000000000000000)) ? 1 : 0;
  int e = (int) ((val & U64(0x7f80000000000000)) >> 55);
  s64 f = (val & U64(0x007fffffffffffff));
  f |= U64(0x0080000000000000);

  double  res;

  if(e == 0)
    res = 0.0;
  else
    res = (s ? -1.0 : 1.0) * pow((double) 2.0, e - 128) * ((double) f / (double) (s64) U64(0x0100000000000000));

#if defined(DEBUG_FP_CONVERSION)
  printf("d->host: %016"LL "x -> %f   \n", val, res);
#endif
  return res;
}

inline double s2host(u64 val)
{
  double  res;

#if defined(FLOAT_IS_IEEE)
  if(sizeof(double) == 8)
  {
    union s2h_conv
    {
      u64     a;
      double  b;
    } f_ieee;
    f_ieee.a = val;
    res = f_ieee.b;
  }
  else
#endif
  {
    int s = (val & U64(0x8000000000000000)) ? 1 : 0;
    int e = (int) ((val & U64(0x7ff0000000000000)) >> 52);
    s64 f = (val & U64(0x000fffffffffffff));

    if(e == 2047)
    {
      if(f)
        res = (s ? -0.0 : 0.0) / 0.0; // NaN
      else
        res = (s ? -1.0 : 1.0) / 0.0; // +/- Inf
    }
    else if(e == 0)
    {
      if(f)
        res = (s ? -1.0 : 1.0) * ldexp((double) f / (double) ((s64) U64(0x10000000000000)),
                                                 -1022);
      else
        res = (s ? -1.0 : 1.0) * 0.0;
    }
    else
    {
      res = (s ? -1.0 : 1.0) * ldexp(1.0 + ((double) f / (double) ((s64) U64(0x0010000000000000))),
                                                 e - 1023);
    }
  }

#if defined(DEBUG_FP_CONVERSION)
  printf("s/t->host: %016"LL "x -> %f   \n", val, res);
#endif
  return res;
}

#define t2host  s2host

inline bool i_isnan(u64 val)
{
  int e = (int) ((val & U64(0x7ff0000000000000)) >> 52);
  s64 f = (val & U64(0x000fffffffffffff));

  return(e == 2047) && f;
}

inline u64 host2f(double val)
{
  double  fr;
  double  v = val;
  int     s = (v < 0.0) ? 1 : 0;
  if(s)
    v *= -1.0;

  int   e = (int) (log((double) v) / log((double) 2.0));
  bool  exp_down = true;

  if(val == 0.0)
    return 0;

  fr = v / pow((double) 2.0, e);

  while((fr >= 1.0 && e < 127) || e < -127)
  {
    e++;
    exp_down = false;
    fr = v / pow((double) 2.0, e);
  }

  while(((fr < 0.5 && e > -127) || e > 127) && exp_down)
  {
    e--;
    fr = v / pow((double) 2.0, e);
  }

  e += 1024;

  u64 f = (u64) (fr * (double) U64(0x0020000000000000) + 0.5);

  f = (s ? U64(0x8000000000000000) : 0) | (((u64) e << 52) & U64(0x7ff0000000000000)) | (f & U64(0x000fffffe0000000));

#if defined(DEBUG_FP_CONVERSION)
  printf("host->f: %f -> %016"LL "x   \n", val, f);
#endif
  return f;
}

inline u64 host2g(double val)
{
  double  fr;
  double  v = val;
  int     s = (v < 0.0) ? 1 : 0;
  if(s)
    v *= -1.0;

  int   e = (int) (log((double) v) / log((double) 2.0));
  bool  exp_down = true;

  if(val == 0.0)
    return 0;

  fr = v / pow((double) 2.0, e);

  while((fr >= 1.0 && e < 1023) || e < -1023)
  {
    e++;
    exp_down = false;
    fr = v / pow((double) 2.0, e);
  }

  while(((fr < 0.5 && e > -1023) || e > 1023) && exp_down)
  {
    e--;
    fr = v / pow((double) 2.0, e);
  }

  e += 1024;

  u64 f = (u64) (fr * (double) U64(0x0020000000000000) + 0.5);

  f = (s ? U64(0x8000000000000000) : 0) | (((u64) e << 52) & U64(0x7ff0000000000000)) | (f & U64(0x000fffffffffffff));

#if defined(DEBUG_FP_CONVERSION)
  printf("host->g: %f -> %016"LL "x   \n", val, f);
#endif
  return f;
}

inline u64 host2d(double val)
{
  double  fr;
  double  v = val;
  int     s = (v < 0.0) ? 1 : 0;
  if(s)
    v *= -1.0;

  int   e = (int) (log((double) v) / log((double) 2.0));
  bool  exp_down = true;

  if(val == 0.0)
    return 0;

  fr = v / pow((double) 2.0, e);

  while((fr >= 1.0 && e < 127) || e < -127)
  {
    e++;
    exp_down = false;
    fr = v / pow((double) 2.0, e);
  }

  while(((fr < 0.5 && e > -127) || e > 127) && exp_down)
  {
    e--;
    fr = v / pow((double) 2.0, e);
  }

  e += 128;

  u64 f = (u64) (fr * (double) U64(0x0100000000000000) + 0.5);

  f = (s ? U64(0x8000000000000000) : 0) | (((u64) e << 55) & U64(0x7f80000000000000)) | (f & U64(0x007fffffffffffff));

#if defined(DEBUG_FP_CONVERSION)
  printf("host->d: %f -> %016"LL "x   \n", val, f);
#endif
  return f;
}

inline u32 map_s(u32 val)
{
  if(val == 0)
    return 0;
  else if(val == 0xff)
    return 0x7ff;
  else if(val & 0x80)
    return(val & 0x7f) | 0x400;
  else
    return(val & 0x7f) | 0x380;
}

inline u64 host2s(double val)
{
  u64 f;
  int s;
  int e;
#if defined(FLOAT_IS_IEEE)
  if(sizeof(float) == 4)
  {
    union h2s_conv
    {
      u32   a;
      float b;
    } f_ieee;
    f_ieee.b = (float) val;
    s = (f_ieee.a >> 31) & 1;
    e = (f_ieee.a >> 23) & 0xff;
    f = (u64) (f_ieee.a >> 0 & 0x7fffff) << 29;
  }
  else
#endif
  {
    double  v = val;
    s = (v < 0.0) ? 1 : 0;
    if(s)
      v *= -1.0;
    e = (int) (log((double) v) / log((double) 2.0));

    double  fr;
    bool    exp_down = true;

    if(val == 0.0)
      return 0;

    fr = v / pow((double) 2.0, e);

    while((fr >= 2.0 && e < 127) || e < -127)
    {
      e++;
      exp_down = false;
      fr = v / pow((double) 2.0, e);
    }

    while(((fr < 1.0 && e > -127) || e > 127) && exp_down)
    {
      e--;
      fr = v / pow((double) 2.0, e);
    }

    e += 255;

    if(e == 0)
      fr = v / pow((double) 2.0, -126);

    f = (u64) (fr * (double) U64(0x0010000000000000) + 0.5);
  }

  e = map_s(e);

  f = (s ? U64(0x800000000000000) : 0) | (((u64) e << 52) & U64(0x7ff0000000000000)) | (f & U64(0x000fffffe0000000));

#if defined(DEBUG_FP_CONVERSION)
  printf("host->s: %f -> %016"LL "x   \n", val, f);
#endif
  return f;
}

inline u64 host2t(double val)
{
  u64 f;
#if defined(FLOAT_IS_IEEE)
  if(sizeof(double) == 8)
  {
    union h2t_conv
    {
      u64     a;
      double  b;
    } f_ieee;
    f_ieee.b = val;
    f = f_ieee.a;
  }
  else
#endif
  {
    double  v = val;
    int     s = (v < 0.0) ? 1 : 0;
    if(s)
      v *= -1.0;

    int     e = (int) (log((double) v) / log((double) 2.0));
    double  fr;
    bool    exp_down = true;

    if(val == 0.0)
      return 0;

    fr = v / pow((double) 2.0, e);

    while((fr >= 2.0 && e < 1023) || e < -1023)
    {
      e++;
      exp_down = false;
      fr = v / pow((double) 2.0, e);
    }

    while(((fr < 1.0 && e > -1023) || e > 1023) && exp_down)
    {
      e--;
      fr = v / pow((double) 2.0, e);
    }

    e += 1023;

    if(e == 0)
      fr = v / pow((double) 2.0, -1022);

    f = (u64) (fr * (double) U64(0x0010000000000000) + 0.5);

    f = (s ? U64(0x800000000000000) : 0) |
      (((u64) e << 52) & U64(0x7ff0000000000000)) |
        (f & U64(0x000fffffffffffff));
  }

#if defined(DEBUG_FP_CONVERSION)
  printf("host->t: %f -> %016"LL "x   \n", val, f);
#endif
  return f;
}

inline u32 store_f(u64 val)
{
  u64 retval = (val & U64(0x00001fffe0000000)) >> 13; /* frac.lo          : 29..44 --> 16..31 */
  retval |= (val & U64(0xc000000000000000)) >> 48;    /* exp.hi + sign    : 62..63 --> 14..15 */
  retval |= (val & U64(0x07ffe00000000000)) >> 45;    /* frac.hi + exp.lo : 45..58 -->  0..13 */

#if defined(DEBUG_FP_LOADSTORE)
  printf("f->mem: %016"LL "x -> %08x   \n", val, retval);
#endif
  return(u32) retval;
}

inline u64 store_g(u64 val)
{
  u64 retval = (val >> 48) & U64(0x000000000000ffff);
  retval |= (val >> 16) & U64(0x00000000ffff0000);
  retval |= (val << 48) & U64(0xffff000000000000);
  retval |= (val << 16) & U64(0x0000ffff00000000);

#if defined(DEBUG_FP_LOADSTORE)
  printf("g->mem: %016"LL "x -> %016"LL "x   \n", val, retval);
#endif
  return retval;
}

inline u64 load_f(u32 val)
{
  u64 retval = (u64) (val & 0xffff0000) << 13;  /* frac.lo          : 16..31 --> 29..44 */
  retval |= (u64) (val & 0x0000c000) << 48;     /* exp.hi + sign    : 14..15 --> 62..63 */
  retval |= (u64) (val & 0x00003fff) << 45;     /* frac.hi + exp.lo :  0..13 --> 45..58 */
  if(((val & 0x00004000) == 0) && ((val & 0x00003f80) != 0))
    retval |= U64(0x3800000000000000);          /* exp.mid */

#if defined(DEBUG_FP_LOADSTORE)
  printf("mem->f: %08x -> %016"LL "x   \n", val, retval);
#endif
  return retval;
}

inline u64 itof_f(u64 val)
{
  u64 retval = (val & U64(0x3fffffff)) << 29; /* frac + exp.lo  :  0..29 --> 29..58 */
  retval |= (val & U64(0xc0000000)) << 32;    /* exp.hi + sign : 30..31 --> 62..63 */
  if(((val & U64(0x40000000)) == 0) && ((val & U64(0x3f800000)) != 0))
    retval |= U64(0x3800000000000000);        /* exp.mid */

#if defined(DEBUG_FP_LOADSTORE)
  printf("reg->f: %08x -> %016"LL "x   \n", val, retval);
#endif
  return retval;
}

inline u64 load_g(u64 val)
{
  u64 retval = (val & U64(0x000000000000ffff)) << 48;
  retval |= (val & U64(0x00000000ffff0000)) << 16;
  retval |= (val & U64(0x0000ffff00000000)) >> 16;
  retval |= (val & U64(0xffff000000000000)) >> 48;

#if defined(DEBUG_FP_LOADSTORE)
  printf("mem->g: %016"LL "x -> %016"LL "x   \n", val, retval);
#endif
  return retval;
}

inline u64 load_s(u32 val)
{
  return((val & U64(0x80000000)) << 32)     // sign
  | ((u64) map_s((val >> 23) & 0xff) << 52) // exp
  | ((val & U64(0x7fffff)) << 29);
}

inline u32 store_s(u64 val)
{
  return((u32) (val >> 32) & 0xc0000000) | ((u32) (val >> 29) & 0x3fffffff);
}

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