nkeynes@1265: /* IEEE floating point support routines, for GDB, the GNU Debugger.
nkeynes@1265:    Copyright 1991, 1994, 1999, 2000, 2003, 2005, 2006, 2010
nkeynes@1265:    Free Software Foundation, Inc.
nkeynes@1265: 
nkeynes@1265: This file is part of GDB.
nkeynes@1265: 
nkeynes@1265: This program is free software; you can redistribute it and/or modify
nkeynes@1265: it under the terms of the GNU General Public License as published by
nkeynes@1265: the Free Software Foundation; either version 2 of the License, or
nkeynes@1265: (at your option) any later version.
nkeynes@1265: 
nkeynes@1265: This program is distributed in the hope that it will be useful,
nkeynes@1265: but WITHOUT ANY WARRANTY; without even the implied warranty of
nkeynes@1265: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
nkeynes@1265: GNU General Public License for more details.
nkeynes@1265: 
nkeynes@1265: You should have received a copy of the GNU General Public License
nkeynes@1265: along with this program; if not, write to the Free Software
nkeynes@1265: Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
nkeynes@1265: 
nkeynes@1265: #ifdef HAVE_CONFIG_H
nkeynes@1265: #include "config.h"
nkeynes@1265: #endif
nkeynes@1265: 
nkeynes@1265: #include <math.h>
nkeynes@1265: 
nkeynes@1265: #ifdef HAVE_STRING_H
nkeynes@1265: #include <string.h>
nkeynes@1265: #endif
nkeynes@1265: 
nkeynes@1265: /* On some platforms, <float.h> provides DBL_QNAN.  */
nkeynes@1265: #ifdef STDC_HEADERS
nkeynes@1265: #include <float.h>
nkeynes@1265: #endif
nkeynes@1265: 
nkeynes@1265: #include "ansidecl.h"
nkeynes@1265: #include "floatformat.h"
nkeynes@1265: 
nkeynes@1265: #ifndef INFINITY
nkeynes@1265: #ifdef HUGE_VAL
nkeynes@1265: #define INFINITY HUGE_VAL
nkeynes@1265: #else
nkeynes@1265: #define INFINITY (1.0 / 0.0)
nkeynes@1265: #endif
nkeynes@1265: #endif
nkeynes@1265: 
nkeynes@1265: #ifndef NAN
nkeynes@1265: #ifdef DBL_QNAN
nkeynes@1265: #define NAN DBL_QNAN
nkeynes@1265: #else
nkeynes@1265: #define NAN (0.0 / 0.0)
nkeynes@1265: #endif
nkeynes@1265: #endif
nkeynes@1265: 
nkeynes@1265: static int mant_bits_set (const struct floatformat *, const unsigned char *);
nkeynes@1265: static unsigned long get_field (const unsigned char *,
nkeynes@1265:                                 enum floatformat_byteorders,
nkeynes@1265:                                 unsigned int,
nkeynes@1265:                                 unsigned int,
nkeynes@1265:                                 unsigned int);
nkeynes@1265: static int floatformat_always_valid (const struct floatformat *fmt,
nkeynes@1265:                                      const void *from);
nkeynes@1265: 
nkeynes@1265: static int
nkeynes@1265: floatformat_always_valid (const struct floatformat *fmt ATTRIBUTE_UNUSED,
nkeynes@1265:                           const void *from ATTRIBUTE_UNUSED)
nkeynes@1265: {
nkeynes@1265:   return 1;
nkeynes@1265: }
nkeynes@1265: 
nkeynes@1265: /* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not
nkeynes@1265:    going to bother with trying to muck around with whether it is defined in
nkeynes@1265:    a system header, what we do if not, etc.  */
nkeynes@1265: #define FLOATFORMAT_CHAR_BIT 8
nkeynes@1265: 
nkeynes@1265: /* floatformats for IEEE half, single and double, big and little endian.  */
nkeynes@1265: const struct floatformat floatformat_ieee_half_big =
nkeynes@1265: {
nkeynes@1265:   floatformat_big, 16, 0, 1, 5, 15, 31, 6, 10,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_ieee_half_big",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_ieee_half_little =
nkeynes@1265: {
nkeynes@1265:   floatformat_little, 16, 0, 1, 5, 15, 31, 6, 10,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_ieee_half_little",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_ieee_single_big =
nkeynes@1265: {
nkeynes@1265:   floatformat_big, 32, 0, 1, 8, 127, 255, 9, 23,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_ieee_single_big",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_ieee_single_little =
nkeynes@1265: {
nkeynes@1265:   floatformat_little, 32, 0, 1, 8, 127, 255, 9, 23,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_ieee_single_little",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_ieee_double_big =
nkeynes@1265: {
nkeynes@1265:   floatformat_big, 64, 0, 1, 11, 1023, 2047, 12, 52,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_ieee_double_big",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_ieee_double_little =
nkeynes@1265: {
nkeynes@1265:   floatformat_little, 64, 0, 1, 11, 1023, 2047, 12, 52,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_ieee_double_little",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: 
nkeynes@1265: /* floatformat for IEEE double, little endian byte order, with big endian word
nkeynes@1265:    ordering, as on the ARM.  */
nkeynes@1265: 
nkeynes@1265: const struct floatformat floatformat_ieee_double_littlebyte_bigword =
nkeynes@1265: {
nkeynes@1265:   floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_ieee_double_littlebyte_bigword",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: 
nkeynes@1265: /* floatformat for VAX.  Not quite IEEE, but close enough.  */
nkeynes@1265: 
nkeynes@1265: const struct floatformat floatformat_vax_f =
nkeynes@1265: {
nkeynes@1265:   floatformat_vax, 32, 0, 1, 8, 129, 0, 9, 23,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_vax_f",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_vax_d =
nkeynes@1265: {
nkeynes@1265:   floatformat_vax, 64, 0, 1, 8, 129, 0, 9, 55,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_vax_d",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_vax_g =
nkeynes@1265: {
nkeynes@1265:   floatformat_vax, 64, 0, 1, 11, 1025, 0, 12, 52,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_vax_g",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: 
nkeynes@1265: static int floatformat_i387_ext_is_valid (const struct floatformat *fmt,
nkeynes@1265: 					  const void *from);
nkeynes@1265: 
nkeynes@1265: static int
nkeynes@1265: floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from)
nkeynes@1265: {
nkeynes@1265:   /* In the i387 double-extended format, if the exponent is all ones,
nkeynes@1265:      then the integer bit must be set.  If the exponent is neither 0
nkeynes@1265:      nor ~0, the intbit must also be set.  Only if the exponent is
nkeynes@1265:      zero can it be zero, and then it must be zero.  */
nkeynes@1265:   unsigned long exponent, int_bit;
nkeynes@1265:   const unsigned char *ufrom = (const unsigned char *) from;
nkeynes@1265: 
nkeynes@1265:   exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
nkeynes@1265: 			fmt->exp_start, fmt->exp_len);
nkeynes@1265:   int_bit = get_field (ufrom, fmt->byteorder, fmt->totalsize,
nkeynes@1265: 		       fmt->man_start, 1);
nkeynes@1265: 
nkeynes@1265:   if ((exponent == 0) != (int_bit == 0))
nkeynes@1265:     return 0;
nkeynes@1265:   else
nkeynes@1265:     return 1;
nkeynes@1265: }
nkeynes@1265: 
nkeynes@1265: const struct floatformat floatformat_i387_ext =
nkeynes@1265: {
nkeynes@1265:   floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
nkeynes@1265:   floatformat_intbit_yes,
nkeynes@1265:   "floatformat_i387_ext",
nkeynes@1265:   floatformat_i387_ext_is_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_m68881_ext =
nkeynes@1265: {
nkeynes@1265:   /* Note that the bits from 16 to 31 are unused.  */
nkeynes@1265:   floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64,
nkeynes@1265:   floatformat_intbit_yes,
nkeynes@1265:   "floatformat_m68881_ext",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_i960_ext =
nkeynes@1265: {
nkeynes@1265:   /* Note that the bits from 0 to 15 are unused.  */
nkeynes@1265:   floatformat_little, 96, 16, 17, 15, 0x3fff, 0x7fff, 32, 64,
nkeynes@1265:   floatformat_intbit_yes,
nkeynes@1265:   "floatformat_i960_ext",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_m88110_ext =
nkeynes@1265: {
nkeynes@1265:   floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
nkeynes@1265:   floatformat_intbit_yes,
nkeynes@1265:   "floatformat_m88110_ext",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_m88110_harris_ext =
nkeynes@1265: {
nkeynes@1265:   /* Harris uses raw format 128 bytes long, but the number is just an ieee
nkeynes@1265:      double, and the last 64 bits are wasted. */
nkeynes@1265:   floatformat_big,128, 0, 1, 11,  0x3ff,  0x7ff, 12, 52,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_m88110_ext_harris",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_arm_ext_big =
nkeynes@1265: {
nkeynes@1265:   /* Bits 1 to 16 are unused.  */
nkeynes@1265:   floatformat_big, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64,
nkeynes@1265:   floatformat_intbit_yes,
nkeynes@1265:   "floatformat_arm_ext_big",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_arm_ext_littlebyte_bigword =
nkeynes@1265: {
nkeynes@1265:   /* Bits 1 to 16 are unused.  */
nkeynes@1265:   floatformat_littlebyte_bigword, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64,
nkeynes@1265:   floatformat_intbit_yes,
nkeynes@1265:   "floatformat_arm_ext_littlebyte_bigword",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_ia64_spill_big =
nkeynes@1265: {
nkeynes@1265:   floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
nkeynes@1265:   floatformat_intbit_yes,
nkeynes@1265:   "floatformat_ia64_spill_big",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_ia64_spill_little =
nkeynes@1265: {
nkeynes@1265:   floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
nkeynes@1265:   floatformat_intbit_yes,
nkeynes@1265:   "floatformat_ia64_spill_little",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_ia64_quad_big =
nkeynes@1265: {
nkeynes@1265:   floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_ia64_quad_big",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: const struct floatformat floatformat_ia64_quad_little =
nkeynes@1265: {
nkeynes@1265:   floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_ia64_quad_little",
nkeynes@1265:   floatformat_always_valid,
nkeynes@1265:   NULL
nkeynes@1265: };
nkeynes@1265: 
nkeynes@1265: static int
nkeynes@1265: floatformat_ibm_long_double_is_valid (const struct floatformat *fmt,
nkeynes@1265: 				      const void *from)
nkeynes@1265: {
nkeynes@1265:   const unsigned char *ufrom = (const unsigned char *) from;
nkeynes@1265:   const struct floatformat *hfmt = fmt->split_half;
nkeynes@1265:   long top_exp, bot_exp;
nkeynes@1265:   int top_nan = 0;
nkeynes@1265: 
nkeynes@1265:   top_exp = get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
nkeynes@1265: 		       hfmt->exp_start, hfmt->exp_len);
nkeynes@1265:   bot_exp = get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize,
nkeynes@1265: 		       hfmt->exp_start, hfmt->exp_len);
nkeynes@1265: 
nkeynes@1265:   if ((unsigned long) top_exp == hfmt->exp_nan)
nkeynes@1265:     top_nan = mant_bits_set (hfmt, ufrom);
nkeynes@1265: 
nkeynes@1265:   /* A NaN is valid with any low part.  */
nkeynes@1265:   if (top_nan)
nkeynes@1265:     return 1;
nkeynes@1265: 
nkeynes@1265:   /* An infinity, zero or denormal requires low part 0 (positive or
nkeynes@1265:      negative).  */
nkeynes@1265:   if ((unsigned long) top_exp == hfmt->exp_nan || top_exp == 0)
nkeynes@1265:     {
nkeynes@1265:       if (bot_exp != 0)
nkeynes@1265: 	return 0;
nkeynes@1265: 
nkeynes@1265:       return !mant_bits_set (hfmt, ufrom + 8);
nkeynes@1265:     }
nkeynes@1265: 
nkeynes@1265:   /* The top part is now a finite normal value.  The long double value
nkeynes@1265:      is the sum of the two parts, and the top part must equal the
nkeynes@1265:      result of rounding the long double value to nearest double.  Thus
nkeynes@1265:      the bottom part must be <= 0.5ulp of the top part in absolute
nkeynes@1265:      value, and if it is < 0.5ulp then the long double is definitely
nkeynes@1265:      valid.  */
nkeynes@1265:   if (bot_exp < top_exp - 53)
nkeynes@1265:     return 1;
nkeynes@1265:   if (bot_exp > top_exp - 53 && bot_exp != 0)
nkeynes@1265:     return 0;
nkeynes@1265:   if (bot_exp == 0)
nkeynes@1265:     {
nkeynes@1265:       /* The bottom part is 0 or denormal.  Determine which, and if
nkeynes@1265: 	 denormal the first two set bits.  */
nkeynes@1265:       int first_bit = -1, second_bit = -1, cur_bit;
nkeynes@1265:       for (cur_bit = 0; (unsigned int) cur_bit < hfmt->man_len; cur_bit++)
nkeynes@1265: 	if (get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize,
nkeynes@1265: 		       hfmt->man_start + cur_bit, 1))
nkeynes@1265: 	  {
nkeynes@1265: 	    if (first_bit == -1)
nkeynes@1265: 	      first_bit = cur_bit;
nkeynes@1265: 	    else
nkeynes@1265: 	      {
nkeynes@1265: 		second_bit = cur_bit;
nkeynes@1265: 		break;
nkeynes@1265: 	      }
nkeynes@1265: 	  }
nkeynes@1265:       /* Bottom part 0 is OK.  */
nkeynes@1265:       if (first_bit == -1)
nkeynes@1265: 	return 1;
nkeynes@1265:       /* The real exponent of the bottom part is -first_bit.  */
nkeynes@1265:       if (-first_bit < top_exp - 53)
nkeynes@1265: 	return 1;
nkeynes@1265:       if (-first_bit > top_exp - 53)
nkeynes@1265: 	return 0;
nkeynes@1265:       /* The bottom part is at least 0.5ulp of the top part.  For this
nkeynes@1265: 	 to be OK, the bottom part must be exactly 0.5ulp (i.e. no
nkeynes@1265: 	 more bits set) and the top part must have last bit 0.  */
nkeynes@1265:       if (second_bit != -1)
nkeynes@1265: 	return 0;
nkeynes@1265:       return !get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
nkeynes@1265: 			 hfmt->man_start + hfmt->man_len - 1, 1);
nkeynes@1265:     }
nkeynes@1265:   else
nkeynes@1265:     {
nkeynes@1265:       /* The bottom part is at least 0.5ulp of the top part.  For this
nkeynes@1265: 	 to be OK, it must be exactly 0.5ulp (i.e. no explicit bits
nkeynes@1265: 	 set) and the top part must have last bit 0.  */
nkeynes@1265:       if (get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
nkeynes@1265: 		     hfmt->man_start + hfmt->man_len - 1, 1))
nkeynes@1265: 	return 0;
nkeynes@1265:       return !mant_bits_set (hfmt, ufrom + 8);
nkeynes@1265:     }
nkeynes@1265: }
nkeynes@1265: 
nkeynes@1265: const struct floatformat floatformat_ibm_long_double =
nkeynes@1265: {
nkeynes@1265:   floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52,
nkeynes@1265:   floatformat_intbit_no,
nkeynes@1265:   "floatformat_ibm_long_double",
nkeynes@1265:   floatformat_ibm_long_double_is_valid,
nkeynes@1265:   &floatformat_ieee_double_big
nkeynes@1265: };
nkeynes@1265: 
nkeynes@1265: 
nkeynes@1265: #ifndef min
nkeynes@1265: #define min(a, b) ((a) < (b) ? (a) : (b))
nkeynes@1265: #endif
nkeynes@1265: 
nkeynes@1265: /* Return 1 if any bits are explicitly set in the mantissa of UFROM,
nkeynes@1265:    format FMT, 0 otherwise.  */
nkeynes@1265: static int
nkeynes@1265: mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom)
nkeynes@1265: {
nkeynes@1265:   unsigned int mant_bits, mant_off;
nkeynes@1265:   int mant_bits_left;
nkeynes@1265: 
nkeynes@1265:   mant_off = fmt->man_start;
nkeynes@1265:   mant_bits_left = fmt->man_len;
nkeynes@1265:   while (mant_bits_left > 0)
nkeynes@1265:     {
nkeynes@1265:       mant_bits = min (mant_bits_left, 32);
nkeynes@1265: 
nkeynes@1265:       if (get_field (ufrom, fmt->byteorder, fmt->totalsize,
nkeynes@1265: 		     mant_off, mant_bits) != 0)
nkeynes@1265: 	return 1;
nkeynes@1265: 
nkeynes@1265:       mant_off += mant_bits;
nkeynes@1265:       mant_bits_left -= mant_bits;
nkeynes@1265:     }
nkeynes@1265:   return 0;
nkeynes@1265: }
nkeynes@1265: 
nkeynes@1265: /* Extract a field which starts at START and is LEN bits long.  DATA and
nkeynes@1265:    TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER.  */
nkeynes@1265: static unsigned long
nkeynes@1265: get_field (const unsigned char *data, enum floatformat_byteorders order,
nkeynes@1265:            unsigned int total_len, unsigned int start, unsigned int len)
nkeynes@1265: {
nkeynes@1265:   unsigned long result = 0;
nkeynes@1265:   unsigned int cur_byte;
nkeynes@1265:   int lo_bit, hi_bit, cur_bitshift = 0;
nkeynes@1265:   int nextbyte = (order == floatformat_little) ? 1 : -1;
nkeynes@1265: 
nkeynes@1265:   /* Start is in big-endian bit order!  Fix that first.  */
nkeynes@1265:   start = total_len - (start + len);
nkeynes@1265: 
nkeynes@1265:   /* Start at the least significant part of the field.  */
nkeynes@1265:   if (order == floatformat_little)
nkeynes@1265:     cur_byte = start / FLOATFORMAT_CHAR_BIT;
nkeynes@1265:   else
nkeynes@1265:     cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
nkeynes@1265: 
nkeynes@1265:   lo_bit = start % FLOATFORMAT_CHAR_BIT;
nkeynes@1265:   hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
nkeynes@1265:   
nkeynes@1265:   do
nkeynes@1265:     {
nkeynes@1265:       unsigned int shifted = *(data + cur_byte) >> lo_bit;
nkeynes@1265:       unsigned int bits = hi_bit - lo_bit;
nkeynes@1265:       unsigned int mask = (1 << bits) - 1;
nkeynes@1265:       result |= (shifted & mask) << cur_bitshift;
nkeynes@1265:       len -= bits;
nkeynes@1265:       cur_bitshift += bits;
nkeynes@1265:       cur_byte += nextbyte;
nkeynes@1265:       lo_bit = 0;
nkeynes@1265:       hi_bit = min (len, FLOATFORMAT_CHAR_BIT);
nkeynes@1265:     }
nkeynes@1265:   while (len != 0);
nkeynes@1265: 
nkeynes@1265:   return result;
nkeynes@1265: }
nkeynes@1265:   
nkeynes@1265: /* Convert from FMT to a double.
nkeynes@1265:    FROM is the address of the extended float.
nkeynes@1265:    Store the double in *TO.  */
nkeynes@1265: 
nkeynes@1265: void
nkeynes@1265: floatformat_to_double (const struct floatformat *fmt,
nkeynes@1265:                        const void *from, double *to)
nkeynes@1265: {
nkeynes@1265:   const unsigned char *ufrom = (const unsigned char *) from;
nkeynes@1265:   double dto;
nkeynes@1265:   long exponent;
nkeynes@1265:   unsigned long mant;
nkeynes@1265:   unsigned int mant_bits, mant_off;
nkeynes@1265:   int mant_bits_left;
nkeynes@1265:   int special_exponent;		/* It's a NaN, denorm or zero */
nkeynes@1265: 
nkeynes@1265:   /* Split values are not handled specially, since the top half has
nkeynes@1265:      the correctly rounded double value (in the only supported case of
nkeynes@1265:      split values).  */
nkeynes@1265: 
nkeynes@1265:   exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
nkeynes@1265: 			fmt->exp_start, fmt->exp_len);
nkeynes@1265: 
nkeynes@1265:   /* If the exponent indicates a NaN, we don't have information to
nkeynes@1265:      decide what to do.  So we handle it like IEEE, except that we
nkeynes@1265:      don't try to preserve the type of NaN.  FIXME.  */
nkeynes@1265:   if ((unsigned long) exponent == fmt->exp_nan)
nkeynes@1265:     {
nkeynes@1265:       int nan = mant_bits_set (fmt, ufrom);
nkeynes@1265: 
nkeynes@1265:       /* On certain systems (such as GNU/Linux), the use of the
nkeynes@1265: 	 INFINITY macro below may generate a warning that can not be
nkeynes@1265: 	 silenced due to a bug in GCC (PR preprocessor/11931).  The
nkeynes@1265: 	 preprocessor fails to recognise the __extension__ keyword in
nkeynes@1265: 	 conjunction with the GNU/C99 extension for hexadecimal
nkeynes@1265: 	 floating point constants and will issue a warning when
nkeynes@1265: 	 compiling with -pedantic.  */
nkeynes@1265:       if (nan)
nkeynes@1265: 	dto = NAN;
nkeynes@1265:       else
nkeynes@1265: 	dto = INFINITY;
nkeynes@1265: 
nkeynes@1265:       if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1))
nkeynes@1265: 	dto = -dto;
nkeynes@1265: 
nkeynes@1265:       *to = dto;
nkeynes@1265: 
nkeynes@1265:       return;
nkeynes@1265:     }
nkeynes@1265: 
nkeynes@1265:   mant_bits_left = fmt->man_len;
nkeynes@1265:   mant_off = fmt->man_start;
nkeynes@1265:   dto = 0.0;
nkeynes@1265: 
nkeynes@1265:   special_exponent = exponent == 0 || (unsigned long) exponent == fmt->exp_nan;
nkeynes@1265: 
nkeynes@1265:   /* Don't bias zero's, denorms or NaNs.  */
nkeynes@1265:   if (!special_exponent)
nkeynes@1265:     exponent -= fmt->exp_bias;
nkeynes@1265: 
nkeynes@1265:   /* Build the result algebraically.  Might go infinite, underflow, etc;
nkeynes@1265:      who cares. */
nkeynes@1265: 
nkeynes@1265:   /* If this format uses a hidden bit, explicitly add it in now.  Otherwise,
nkeynes@1265:      increment the exponent by one to account for the integer bit.  */
nkeynes@1265: 
nkeynes@1265:   if (!special_exponent)
nkeynes@1265:     {
nkeynes@1265:       if (fmt->intbit == floatformat_intbit_no)
nkeynes@1265: 	dto = ldexp (1.0, exponent);
nkeynes@1265:       else
nkeynes@1265: 	exponent++;
nkeynes@1265:     }
nkeynes@1265: 
nkeynes@1265:   while (mant_bits_left > 0)
nkeynes@1265:     {
nkeynes@1265:       mant_bits = min (mant_bits_left, 32);
nkeynes@1265: 
nkeynes@1265:       mant = get_field (ufrom, fmt->byteorder, fmt->totalsize,
nkeynes@1265: 			 mant_off, mant_bits);
nkeynes@1265: 
nkeynes@1265:       /* Handle denormalized numbers.  FIXME: What should we do for
nkeynes@1265: 	 non-IEEE formats?  */
nkeynes@1265:       if (special_exponent && exponent == 0 && mant != 0)
nkeynes@1265: 	dto += ldexp ((double)mant,
nkeynes@1265: 		      (- fmt->exp_bias
nkeynes@1265: 		       - mant_bits
nkeynes@1265: 		       - (mant_off - fmt->man_start)
nkeynes@1265: 		       + 1));
nkeynes@1265:       else
nkeynes@1265: 	dto += ldexp ((double)mant, exponent - mant_bits);
nkeynes@1265:       if (exponent != 0)
nkeynes@1265: 	exponent -= mant_bits;
nkeynes@1265:       mant_off += mant_bits;
nkeynes@1265:       mant_bits_left -= mant_bits;
nkeynes@1265:     }
nkeynes@1265: 
nkeynes@1265:   /* Negate it if negative.  */
nkeynes@1265:   if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1))
nkeynes@1265:     dto = -dto;
nkeynes@1265:   *to = dto;
nkeynes@1265: }
nkeynes@1265: 
nkeynes@1265: static void put_field (unsigned char *, enum floatformat_byteorders,
nkeynes@1265:                        unsigned int,
nkeynes@1265:                        unsigned int,
nkeynes@1265:                        unsigned int,
nkeynes@1265:                        unsigned long);
nkeynes@1265: 
nkeynes@1265: /* Set a field which starts at START and is LEN bits long.  DATA and
nkeynes@1265:    TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER.  */
nkeynes@1265: static void
nkeynes@1265: put_field (unsigned char *data, enum floatformat_byteorders order,
nkeynes@1265:            unsigned int total_len, unsigned int start, unsigned int len,
nkeynes@1265:            unsigned long stuff_to_put)
nkeynes@1265: {
nkeynes@1265:   unsigned int cur_byte;
nkeynes@1265:   int lo_bit, hi_bit;
nkeynes@1265:   int nextbyte = (order == floatformat_little) ? 1 : -1;
nkeynes@1265: 
nkeynes@1265:   /* Start is in big-endian bit order!  Fix that first.  */
nkeynes@1265:   start = total_len - (start + len);
nkeynes@1265: 
nkeynes@1265:   /* Start at the least significant part of the field.  */
nkeynes@1265:   if (order == floatformat_little)
nkeynes@1265:     cur_byte = start / FLOATFORMAT_CHAR_BIT;
nkeynes@1265:   else
nkeynes@1265:     cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
nkeynes@1265: 
nkeynes@1265:   lo_bit = start % FLOATFORMAT_CHAR_BIT;
nkeynes@1265:   hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
nkeynes@1265:   
nkeynes@1265:   do
nkeynes@1265:     {
nkeynes@1265:       unsigned char *byte_ptr = data + cur_byte;
nkeynes@1265:       unsigned int bits = hi_bit - lo_bit;
nkeynes@1265:       unsigned int mask = ((1 << bits) - 1) << lo_bit;
nkeynes@1265:       *byte_ptr = (*byte_ptr & ~mask) | ((stuff_to_put << lo_bit) & mask);
nkeynes@1265:       stuff_to_put >>= bits;
nkeynes@1265:       len -= bits;
nkeynes@1265:       cur_byte += nextbyte;
nkeynes@1265:       lo_bit = 0;
nkeynes@1265:       hi_bit = min (len, FLOATFORMAT_CHAR_BIT);
nkeynes@1265:     }
nkeynes@1265:   while (len != 0);
nkeynes@1265: }
nkeynes@1265: 
nkeynes@1265: /* The converse: convert the double *FROM to an extended float
nkeynes@1265:    and store where TO points.  Neither FROM nor TO have any alignment
nkeynes@1265:    restrictions.  */
nkeynes@1265: 
nkeynes@1265: void
nkeynes@1265: floatformat_from_double (const struct floatformat *fmt,
nkeynes@1265:                          const double *from, void *to)
nkeynes@1265: {
nkeynes@1265:   double dfrom;
nkeynes@1265:   int exponent;
nkeynes@1265:   double mant;
nkeynes@1265:   unsigned int mant_bits, mant_off;
nkeynes@1265:   int mant_bits_left;
nkeynes@1265:   unsigned char *uto = (unsigned char *) to;
nkeynes@1265: 
nkeynes@1265:   dfrom = *from;
nkeynes@1265:   memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT);
nkeynes@1265: 
nkeynes@1265:   /* Split values are not handled specially, since a bottom half of
nkeynes@1265:      zero is correct for any value representable as double (in the
nkeynes@1265:      only supported case of split values).  */
nkeynes@1265: 
nkeynes@1265:   /* If negative, set the sign bit.  */
nkeynes@1265:   if (dfrom < 0)
nkeynes@1265:     {
nkeynes@1265:       put_field (uto, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1, 1);
nkeynes@1265:       dfrom = -dfrom;
nkeynes@1265:     }
nkeynes@1265: 
nkeynes@1265:   if (dfrom == 0)
nkeynes@1265:     {
nkeynes@1265:       /* 0.0.  */
nkeynes@1265:       return;
nkeynes@1265:     }
nkeynes@1265: 
nkeynes@1265:   if (dfrom != dfrom)
nkeynes@1265:     {
nkeynes@1265:       /* NaN.  */
nkeynes@1265:       put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
nkeynes@1265: 		 fmt->exp_len, fmt->exp_nan);
nkeynes@1265:       /* Be sure it's not infinity, but NaN value is irrelevant.  */
nkeynes@1265:       put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start,
nkeynes@1265: 		 32, 1);
nkeynes@1265:       return;
nkeynes@1265:     }
nkeynes@1265: 
nkeynes@1265:   if (dfrom + dfrom == dfrom)
nkeynes@1265:     {
nkeynes@1265:       /* This can only happen for an infinite value (or zero, which we
nkeynes@1265: 	 already handled above).  */
nkeynes@1265:       put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
nkeynes@1265: 		 fmt->exp_len, fmt->exp_nan);
nkeynes@1265:       return;
nkeynes@1265:     }
nkeynes@1265: 
nkeynes@1265:   mant = frexp (dfrom, &exponent);
nkeynes@1265:   if (exponent + fmt->exp_bias - 1 > 0)
nkeynes@1265:     put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
nkeynes@1265: 	       fmt->exp_len, exponent + fmt->exp_bias - 1);
nkeynes@1265:   else
nkeynes@1265:     {
nkeynes@1265:       /* Handle a denormalized number.  FIXME: What should we do for
nkeynes@1265: 	 non-IEEE formats?  */
nkeynes@1265:       put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
nkeynes@1265: 		 fmt->exp_len, 0);
nkeynes@1265:       mant = ldexp (mant, exponent + fmt->exp_bias - 1);
nkeynes@1265:     }
nkeynes@1265: 
nkeynes@1265:   mant_bits_left = fmt->man_len;
nkeynes@1265:   mant_off = fmt->man_start;
nkeynes@1265:   while (mant_bits_left > 0)
nkeynes@1265:     {
nkeynes@1265:       unsigned long mant_long;
nkeynes@1265:       mant_bits = mant_bits_left < 32 ? mant_bits_left : 32;
nkeynes@1265: 
nkeynes@1265:       mant *= 4294967296.0;
nkeynes@1265:       mant_long = (unsigned long)mant;
nkeynes@1265:       mant -= mant_long;
nkeynes@1265: 
nkeynes@1265:       /* If the integer bit is implicit, and we are not creating a
nkeynes@1265: 	 denormalized number, then we need to discard it.  */
nkeynes@1265:       if ((unsigned int) mant_bits_left == fmt->man_len
nkeynes@1265: 	  && fmt->intbit == floatformat_intbit_no
nkeynes@1265: 	  && exponent + fmt->exp_bias - 1 > 0)
nkeynes@1265: 	{
nkeynes@1265: 	  mant_long &= 0x7fffffff;
nkeynes@1265: 	  mant_bits -= 1;
nkeynes@1265: 	}
nkeynes@1265:       else if (mant_bits < 32)
nkeynes@1265: 	{
nkeynes@1265: 	  /* The bits we want are in the most significant MANT_BITS bits of
nkeynes@1265: 	     mant_long.  Move them to the least significant.  */
nkeynes@1265: 	  mant_long >>= 32 - mant_bits;
nkeynes@1265: 	}
nkeynes@1265: 
nkeynes@1265:       put_field (uto, fmt->byteorder, fmt->totalsize,
nkeynes@1265: 		 mant_off, mant_bits, mant_long);
nkeynes@1265:       mant_off += mant_bits;
nkeynes@1265:       mant_bits_left -= mant_bits;
nkeynes@1265:     }
nkeynes@1265: }
nkeynes@1265: 
nkeynes@1265: /* Return non-zero iff the data at FROM is a valid number in format FMT.  */
nkeynes@1265: 
nkeynes@1265: int
nkeynes@1265: floatformat_is_valid (const struct floatformat *fmt, const void *from)
nkeynes@1265: {
nkeynes@1265:   return fmt->is_valid (fmt, from);
nkeynes@1265: }
nkeynes@1265: 
nkeynes@1265: 
nkeynes@1265: #ifdef IEEE_DEBUG
nkeynes@1265: 
nkeynes@1265: #include <stdio.h>
nkeynes@1265: 
nkeynes@1265: /* This is to be run on a host which uses IEEE floating point.  */
nkeynes@1265: 
nkeynes@1265: void
nkeynes@1265: ieee_test (double n)
nkeynes@1265: {
nkeynes@1265:   double result;
nkeynes@1265: 
nkeynes@1265:   floatformat_to_double (&floatformat_ieee_double_little, &n, &result);
nkeynes@1265:   if ((n != result && (! isnan (n) || ! isnan (result)))
nkeynes@1265:       || (n < 0 && result >= 0)
nkeynes@1265:       || (n >= 0 && result < 0))
nkeynes@1265:     printf ("Differ(to): %.20g -> %.20g\n", n, result);
nkeynes@1265: 
nkeynes@1265:   floatformat_from_double (&floatformat_ieee_double_little, &n, &result);
nkeynes@1265:   if ((n != result && (! isnan (n) || ! isnan (result)))
nkeynes@1265:       || (n < 0 && result >= 0)
nkeynes@1265:       || (n >= 0 && result < 0))
nkeynes@1265:     printf ("Differ(from): %.20g -> %.20g\n", n, result);
nkeynes@1265: 
nkeynes@1265: #if 0
nkeynes@1265:   {
nkeynes@1265:     char exten[16];
nkeynes@1265: 
nkeynes@1265:     floatformat_from_double (&floatformat_m68881_ext, &n, exten);
nkeynes@1265:     floatformat_to_double (&floatformat_m68881_ext, exten, &result);
nkeynes@1265:     if (n != result)
nkeynes@1265:       printf ("Differ(to+from): %.20g -> %.20g\n", n, result);
nkeynes@1265:   }
nkeynes@1265: #endif
nkeynes@1265: 
nkeynes@1265: #if IEEE_DEBUG > 1
nkeynes@1265:   /* This is to be run on a host which uses 68881 format.  */
nkeynes@1265:   {
nkeynes@1265:     long double ex = *(long double *)exten;
nkeynes@1265:     if (ex != n)
nkeynes@1265:       printf ("Differ(from vs. extended): %.20g\n", n);
nkeynes@1265:   }
nkeynes@1265: #endif
nkeynes@1265: }
nkeynes@1265: 
nkeynes@1265: int
nkeynes@1265: main (void)
nkeynes@1265: {
nkeynes@1265:   ieee_test (0.0);
nkeynes@1265:   ieee_test (0.5);
nkeynes@1265:   ieee_test (256.0);
nkeynes@1265:   ieee_test (0.12345);
nkeynes@1265:   ieee_test (234235.78907234);
nkeynes@1265:   ieee_test (-512.0);
nkeynes@1265:   ieee_test (-0.004321);
nkeynes@1265:   ieee_test (1.2E-70);
nkeynes@1265:   ieee_test (1.2E-316);
nkeynes@1265:   ieee_test (4.9406564584124654E-324);
nkeynes@1265:   ieee_test (- 4.9406564584124654E-324);
nkeynes@1265:   ieee_test (- 0.0);
nkeynes@1265:   ieee_test (- INFINITY);
nkeynes@1265:   ieee_test (- NAN);
nkeynes@1265:   ieee_test (INFINITY);
nkeynes@1265:   ieee_test (NAN);
nkeynes@1265:   return 0;
nkeynes@1265: }
nkeynes@1265: #endif