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  1. /* atof_ieee.c - turn a Flonum into an IEEE floating point number
  2.    Copyright 1987, 1992, 1994, 1996, 1997, 1998, 1999, 2000, 2001, 2005,
  3.    2007, 2009  Free Software Foundation, Inc.
  4.  
  5.    This file is part of GAS, the GNU Assembler.
  6.  
  7.    GAS is free software; you can redistribute it and/or modify
  8.    it under the terms of the GNU General Public License as published by
  9.    the Free Software Foundation; either version 3, or (at your option)
  10.    any later version.
  11.  
  12.    GAS is distributed in the hope that it will be useful,
  13.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15.    GNU General Public License for more details.
  16.  
  17.    You should have received a copy of the GNU General Public License
  18.    along with GAS; see the file COPYING.  If not, write to the Free
  19.    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  20.    02110-1301, USA.  */
  21.  
  22. #include "as.h"
  23.  
  24. /* Flonums returned here.  */
  25. extern FLONUM_TYPE generic_floating_point_number;
  26.  
  27. extern const char EXP_CHARS[];
  28. /* Precision in LittleNums.  */
  29. /* Don't count the gap in the m68k extended precision format.  */
  30. #define MAX_PRECISION  5
  31. #define F_PRECISION    2
  32. #define D_PRECISION    4
  33. #define X_PRECISION    5
  34. #define P_PRECISION    5
  35.  
  36. /* Length in LittleNums of guard bits.  */
  37. #define GUARD          2
  38.  
  39. #ifndef TC_LARGEST_EXPONENT_IS_NORMAL
  40. #define TC_LARGEST_EXPONENT_IS_NORMAL(PRECISION) 0
  41. #endif
  42.  
  43. static const unsigned long mask[] =
  44. {
  45.   0x00000000,
  46.   0x00000001,
  47.   0x00000003,
  48.   0x00000007,
  49.   0x0000000f,
  50.   0x0000001f,
  51.   0x0000003f,
  52.   0x0000007f,
  53.   0x000000ff,
  54.   0x000001ff,
  55.   0x000003ff,
  56.   0x000007ff,
  57.   0x00000fff,
  58.   0x00001fff,
  59.   0x00003fff,
  60.   0x00007fff,
  61.   0x0000ffff,
  62.   0x0001ffff,
  63.   0x0003ffff,
  64.   0x0007ffff,
  65.   0x000fffff,
  66.   0x001fffff,
  67.   0x003fffff,
  68.   0x007fffff,
  69.   0x00ffffff,
  70.   0x01ffffff,
  71.   0x03ffffff,
  72.   0x07ffffff,
  73.   0x0fffffff,
  74.   0x1fffffff,
  75.   0x3fffffff,
  76.   0x7fffffff,
  77.   0xffffffff,
  78. };
  80. static int bits_left_in_littlenum;
  81. static int littlenums_left;
  82. static LITTLENUM_TYPE *littlenum_pointer;
  83.  
  84. static int
  85. next_bits (int number_of_bits)
  86. {
  87.   int return_value;
  88.  
  89.   if (!littlenums_left)
  90.     return 0;
  91.  
  92.   if (number_of_bits >= bits_left_in_littlenum)
  93.     {
  94.       return_value = mask[bits_left_in_littlenum] & *littlenum_pointer;
  95.       number_of_bits -= bits_left_in_littlenum;
  96.       return_value <<= number_of_bits;
  97.  
  98.       if (--littlenums_left)
  99.         {
  100.           bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits;
  101.           --littlenum_pointer;
  102.           return_value |=
  103.             (*littlenum_pointer >> bits_left_in_littlenum)
  104.             & mask[number_of_bits];
  105.         }
  106.     }
  107.   else
  108.     {
  109.       bits_left_in_littlenum -= number_of_bits;
  110.       return_value =
  111.         mask[number_of_bits] & (*littlenum_pointer >> bits_left_in_littlenum);
  112.     }
  113.   return return_value;
  114. }
  115.  
  116. /* Num had better be less than LITTLENUM_NUMBER_OF_BITS.  */
  117.  
  118. static void
  119. unget_bits (int num)
  120. {
  121.   if (!littlenums_left)
  122.     {
  123.       ++littlenum_pointer;
  124.       ++littlenums_left;
  125.       bits_left_in_littlenum = num;
  126.     }
  127.   else if (bits_left_in_littlenum + num > LITTLENUM_NUMBER_OF_BITS)
  128.     {
  129.       bits_left_in_littlenum =
  130.         num - (LITTLENUM_NUMBER_OF_BITS - bits_left_in_littlenum);
  131.       ++littlenum_pointer;
  132.       ++littlenums_left;
  133.     }
  134.   else
  135.     bits_left_in_littlenum += num;
  136. }
  137.  
  138. static void
  139. make_invalid_floating_point_number (LITTLENUM_TYPE *words)
  140. {
  141.   as_bad (_("cannot create floating-point number"));
  142.   /* Zero the leftmost bit.  */
  143.   words[0] = (LITTLENUM_TYPE) ((unsigned) -1) >> 1;
  144.   words[1] = (LITTLENUM_TYPE) -1;
  145.   words[2] = (LITTLENUM_TYPE) -1;
  146.   words[3] = (LITTLENUM_TYPE) -1;
  147.   words[4] = (LITTLENUM_TYPE) -1;
  148.   words[5] = (LITTLENUM_TYPE) -1;
  149. }
  151. /* Warning: This returns 16-bit LITTLENUMs.  It is up to the caller to
  152.    figure out any alignment problems and to conspire for the
  153.    bytes/word to be emitted in the right order.  Bigendians beware!  */
  154.  
  155. /* Note that atof-ieee always has X and P precisions enabled.  it is up
  156.    to md_atof to filter them out if the target machine does not support
  157.    them.  */
  158.  
  159. /* Returns pointer past text consumed.  */
  160.  
  161. char *
  162. atof_ieee (char *str,                   /* Text to convert to binary.  */
  163.            int what_kind,               /* 'd', 'f', 'x', 'p'.  */
  164.            LITTLENUM_TYPE *words)       /* Build the binary here.  */
  165. {
  166.   /* Extra bits for zeroed low-order bits.
  167.      The 1st MAX_PRECISION are zeroed, the last contain flonum bits.  */
  168.   static LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD];
  169.   char *return_value;
  170.   /* Number of 16-bit words in the format.  */
  171.   int precision;
  172.   long exponent_bits;
  173.   FLONUM_TYPE save_gen_flonum;
  174.  
  175.   /* We have to save the generic_floating_point_number because it
  176.      contains storage allocation about the array of LITTLENUMs where
  177.      the value is actually stored.  We will allocate our own array of
  178.      littlenums below, but have to restore the global one on exit.  */
  179.   save_gen_flonum = generic_floating_point_number;
  180.  
  181.   return_value = str;
  182.   generic_floating_point_number.low = bits + MAX_PRECISION;
  183.   generic_floating_point_number.high = NULL;
  184.   generic_floating_point_number.leader = NULL;
  185.   generic_floating_point_number.exponent = 0;
  186.   generic_floating_point_number.sign = '\0';
  187.  
  188.   /* Use more LittleNums than seems necessary: the highest flonum may
  189.      have 15 leading 0 bits, so could be useless.  */
  190.  
  191.   memset (bits, '\0', sizeof (LITTLENUM_TYPE) * MAX_PRECISION);
  192.  
  193.   switch (what_kind)
  194.     {
  195.     case 'f':
  196.     case 'F':
  197.     case 's':
  198.     case 'S':
  199.       precision = F_PRECISION;
  200.       exponent_bits = 8;
  201.       break;
  202.  
  203.     case 'd':
  204.     case 'D':
  205.     case 'r':
  206.     case 'R':
  207.       precision = D_PRECISION;
  208.       exponent_bits = 11;
  209.       break;
  210.  
  211.     case 'x':
  212.     case 'X':
  213.     case 'e':
  214.     case 'E':
  215.       precision = X_PRECISION;
  216.       exponent_bits = 15;
  217.       break;
  218.  
  219.     case 'p':
  220.     case 'P':
  221.       precision = P_PRECISION;
  222.       exponent_bits = -1;
  223.       break;
  224.  
  225.     default:
  226.       make_invalid_floating_point_number (words);
  227.       return (NULL);
  228.     }
  229.  
  230.   generic_floating_point_number.high
  231.     = generic_floating_point_number.low + precision - 1 + GUARD;
  232.  
  233.   if (atof_generic (&return_value, ".", EXP_CHARS,
  234.                     &generic_floating_point_number))
  235.     {
  236.       make_invalid_floating_point_number (words);
  237.       return NULL;
  238.     }
  239.   gen_to_words (words, precision, exponent_bits);
  240.  
  241.   /* Restore the generic_floating_point_number's storage alloc (and
  242.      everything else).  */
  243.   generic_floating_point_number = save_gen_flonum;
  244.  
  245.   return return_value;
  246. }
  247.  
  248. /* Turn generic_floating_point_number into a real float/double/extended.  */
  249.  
  250. int
  251. gen_to_words (LITTLENUM_TYPE *words, int precision, long exponent_bits)
  252. {
  253.   int return_value = 0;
  254.  
  255.   long exponent_1;
  256.   long exponent_2;
  257.   long exponent_3;
  258.   long exponent_4;
  259.   int exponent_skippage;
  260.   LITTLENUM_TYPE word1;
  261.   LITTLENUM_TYPE *lp;
  262.   LITTLENUM_TYPE *words_end;
  263.  
  264.   words_end = words + precision;
  265. #ifdef TC_M68K
  266.   if (precision == X_PRECISION)
  267.     /* On the m68k the extended precision format has a gap of 16 bits
  268.        between the exponent and the mantissa.  */
  269.     words_end++;
  270. #endif
  271.  
  272.   if (generic_floating_point_number.low > generic_floating_point_number.leader)
  273.     {
  274.       /* 0.0e0 seen.  */
  275.       if (generic_floating_point_number.sign == '+')
  276.         words[0] = 0x0000;
  277.       else
  278.         words[0] = 0x8000;
  279.       memset (&words[1], '\0',
  280.               (words_end - words - 1) * sizeof (LITTLENUM_TYPE));
  281.       return return_value;
  282.     }
  283.  
  284.   /* NaN:  Do the right thing.  */
  285.   if (generic_floating_point_number.sign == 0)
  286.     {
  287.       if (TC_LARGEST_EXPONENT_IS_NORMAL (precision))
  288.         as_warn (_("NaNs are not supported by this target\n"));
  289.       if (precision == F_PRECISION)
  290.         {
  291.           words[0] = 0x7fff;
  292.           words[1] = 0xffff;
  293.         }
  294.       else if (precision == X_PRECISION)
  295.         {
  296. #ifdef TC_M68K
  297.           words[0] = 0x7fff;
  298.           words[1] = 0;
  299.           words[2] = 0xffff;
  300.           words[3] = 0xffff;
  301.           words[4] = 0xffff;
  302.           words[5] = 0xffff;
  303. #else /* ! TC_M68K  */
  304. #ifdef TC_I386
  305.           words[0] = 0xffff;
  306.           words[1] = 0xc000;
  307.           words[2] = 0;
  308.           words[3] = 0;
  309.           words[4] = 0;
  310. #else /* ! TC_I386  */
  311.           abort ();
  312. #endif /* ! TC_I386  */
  313. #endif /* ! TC_M68K  */
  314.         }
  315.       else
  316.         {
  317.           words[0] = 0x7fff;
  318.           words[1] = 0xffff;
  319.           words[2] = 0xffff;
  320.           words[3] = 0xffff;
  321.         }
  322.       return return_value;
  323.     }
  324.   else if (generic_floating_point_number.sign == 'P')
  325.     {
  326.       if (TC_LARGEST_EXPONENT_IS_NORMAL (precision))
  327.         as_warn (_("Infinities are not supported by this target\n"));
  328.  
  329.       /* +INF:  Do the right thing.  */
  330.       if (precision == F_PRECISION)
  331.         {
  332.           words[0] = 0x7f80;
  333.           words[1] = 0;
  334.         }
  335.       else if (precision == X_PRECISION)
  336.         {
  337. #ifdef TC_M68K
  338.           words[0] = 0x7fff;
  339.           words[1] = 0;
  340.           words[2] = 0;
  341.           words[3] = 0;
  342.           words[4] = 0;
  343.           words[5] = 0;
  344. #else /* ! TC_M68K  */
  345. #ifdef TC_I386
  346.           words[0] = 0x7fff;
  347.           words[1] = 0x8000;
  348.           words[2] = 0;
  349.           words[3] = 0;
  350.           words[4] = 0;
  351. #else /* ! TC_I386  */
  352.           abort ();
  353. #endif /* ! TC_I386  */
  354. #endif /* ! TC_M68K  */
  355.         }
  356.       else
  357.         {
  358.           words[0] = 0x7ff0;
  359.           words[1] = 0;
  360.           words[2] = 0;
  361.           words[3] = 0;
  362.         }
  363.       return return_value;
  364.     }
  365.   else if (generic_floating_point_number.sign == 'N')
  366.     {
  367.       if (TC_LARGEST_EXPONENT_IS_NORMAL (precision))
  368.         as_warn (_("Infinities are not supported by this target\n"));
  369.  
  370.       /* Negative INF.  */
  371.       if (precision == F_PRECISION)
  372.         {
  373.           words[0] = 0xff80;
  374.           words[1] = 0x0;
  375.         }
  376.       else if (precision == X_PRECISION)
  377.         {
  378. #ifdef TC_M68K
  379.           words[0] = 0xffff;
  380.           words[1] = 0;
  381.           words[2] = 0;
  382.           words[3] = 0;
  383.           words[4] = 0;
  384.           words[5] = 0;
  385. #else /* ! TC_M68K  */
  386. #ifdef TC_I386
  387.           words[0] = 0xffff;
  388.           words[1] = 0x8000;
  389.           words[2] = 0;
  390.           words[3] = 0;
  391.           words[4] = 0;
  392. #else /* ! TC_I386  */
  393.           abort ();
  394. #endif /* ! TC_I386  */
  395. #endif /* ! TC_M68K  */
  396.         }
  397.       else
  398.         {
  399.           words[0] = 0xfff0;
  400.           words[1] = 0x0;
  401.           words[2] = 0x0;
  402.           words[3] = 0x0;
  403.         }
  404.       return return_value;
  405.     }
  406.  
  407.   /* The floating point formats we support have:
  408.      Bit 15 is sign bit.
  409.      Bits 14:n are excess-whatever exponent.
  410.      Bits n-1:0 (if any) are most significant bits of fraction.
  411.      Bits 15:0 of the next word(s) are the next most significant bits.
  412.  
  413.      So we need: number of bits of exponent, number of bits of
  414.      mantissa.  */
  415.   bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
  416.   littlenum_pointer = generic_floating_point_number.leader;
  417.   littlenums_left = (1
  418.                      + generic_floating_point_number.leader
  419.                      - generic_floating_point_number.low);
  420.  
  421.   /* Seek (and forget) 1st significant bit.  */
  422.   for (exponent_skippage = 0; !next_bits (1); ++exponent_skippage);
  423.   exponent_1 = (generic_floating_point_number.exponent
  424.                 + generic_floating_point_number.leader
  425.                 + 1
  426.                 - generic_floating_point_number.low);
  427.  
  428.   /* Radix LITTLENUM_RADIX, point just higher than
  429.      generic_floating_point_number.leader.  */
  430.   exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS;
  431.  
  432.   /* Radix 2.  */
  433.   exponent_3 = exponent_2 - exponent_skippage;
  434.  
  435.   /* Forget leading zeros, forget 1st bit.  */
  436.   exponent_4 = exponent_3 + ((1 << (exponent_bits - 1)) - 2);
  437.  
  438.   /* Offset exponent.  */
  439.   lp = words;
  440.  
  441.   /* Word 1.  Sign, exponent and perhaps high bits.  */
  442.   word1 = ((generic_floating_point_number.sign == '+')
  443.            ? 0
  444.            : (1 << (LITTLENUM_NUMBER_OF_BITS - 1)));
  445.  
  446.   /* Assume 2's complement integers.  */
  447.   if (exponent_4 <= 0)
  448.     {
  449.       int prec_bits;
  450.       int num_bits;
  451.  
  452.       unget_bits (1);
  453.       num_bits = -exponent_4;
  454.       prec_bits =
  455.         LITTLENUM_NUMBER_OF_BITS * precision - (exponent_bits + 1 + num_bits);
  456. #ifdef TC_I386
  457.       if (precision == X_PRECISION && exponent_bits == 15)
  458.         {
  459.           /* On the i386 a denormalized extended precision float is
  460.              shifted down by one, effectively decreasing the exponent
  461.              bias by one.  */
  462.           prec_bits -= 1;
  463.           num_bits += 1;
  464.         }
  465. #endif
  466.  
  467.       if (num_bits >= LITTLENUM_NUMBER_OF_BITS - exponent_bits)
  468.         {
  469.           /* Bigger than one littlenum.  */
  470.           num_bits -= (LITTLENUM_NUMBER_OF_BITS - 1) - exponent_bits;
  471.           *lp++ = word1;
  472.           if (num_bits + exponent_bits + 1
  473.               > precision * LITTLENUM_NUMBER_OF_BITS)
  474.             {
  475.               /* Exponent overflow.  */
  476.               make_invalid_floating_point_number (words);
  477.               return return_value;
  478.             }
  479. #ifdef TC_M68K
  480.           if (precision == X_PRECISION && exponent_bits == 15)
  481.             *lp++ = 0;
  482. #endif
  483.           while (num_bits >= LITTLENUM_NUMBER_OF_BITS)
  484.             {
  485.               num_bits -= LITTLENUM_NUMBER_OF_BITS;
  486.               *lp++ = 0;
  487.             }
  488.           if (num_bits)
  489.             *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS - (num_bits));
  490.         }
  491.       else
  492.         {
  493.           if (precision == X_PRECISION && exponent_bits == 15)
  494.             {
  495.               *lp++ = word1;
  496. #ifdef TC_M68K
  497.               *lp++ = 0;
  498. #endif
  499.               *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS - num_bits);
  500.             }
  501.           else
  502.             {
  503.               word1 |= next_bits ((LITTLENUM_NUMBER_OF_BITS - 1)
  504.                                   - (exponent_bits + num_bits));
  505.               *lp++ = word1;
  506.             }
  507.         }
  508.       while (lp < words_end)
  509.         *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS);
  510.  
  511.       /* Round the mantissa up, but don't change the number.  */
  512.       if (next_bits (1))
  513.         {
  514.           --lp;
  515.           if (prec_bits >= LITTLENUM_NUMBER_OF_BITS)
  516.             {
  517.               int n = 0;
  518.               int tmp_bits;
  519.  
  520.               n = 0;
  521.               tmp_bits = prec_bits;
  522.               while (tmp_bits > LITTLENUM_NUMBER_OF_BITS)
  523.                 {
  524.                   if (lp[n] != (LITTLENUM_TYPE) - 1)
  525.                     break;
  526.                   --n;
  527.                   tmp_bits -= LITTLENUM_NUMBER_OF_BITS;
  528.                 }
  529.               if (tmp_bits > LITTLENUM_NUMBER_OF_BITS
  530.                   || (lp[n] & mask[tmp_bits]) != mask[tmp_bits]
  531.                   || (prec_bits != (precision * LITTLENUM_NUMBER_OF_BITS
  532.                                     - exponent_bits - 1)
  533. #ifdef TC_I386
  534.                       /* An extended precision float with only the integer
  535.                          bit set would be invalid.  That must be converted
  536.                          to the smallest normalized number.  */
  537.                       && !(precision == X_PRECISION
  538.                            && prec_bits == (precision * LITTLENUM_NUMBER_OF_BITS
  539.                                             - exponent_bits - 2))
  540. #endif
  541.                       ))
  542.                 {
  543.                   unsigned long carry;
  544.  
  545.                   for (carry = 1; carry && (lp >= words); lp--)
  546.                     {
  547.                       carry = *lp + carry;
  548.                       *lp = carry;
  549.                       carry >>= LITTLENUM_NUMBER_OF_BITS;
  550.                     }
  551.                 }
  552.               else
  553.                 {
  554.                   /* This is an overflow of the denormal numbers.  We
  555.                      need to forget what we have produced, and instead
  556.                      generate the smallest normalized number.  */
  557.                   lp = words;
  558.                   word1 = ((generic_floating_point_number.sign == '+')
  559.                            ? 0
  560.                            : (1 << (LITTLENUM_NUMBER_OF_BITS - 1)));
  561.                   word1 |= (1
  562.                             << ((LITTLENUM_NUMBER_OF_BITS - 1)
  563.                                 - exponent_bits));
  564.                   *lp++ = word1;
  565. #ifdef TC_I386
  566.                   /* Set the integer bit in the extended precision format.
  567.                      This cannot happen on the m68k where the mantissa
  568.                      just overflows into the integer bit above.  */
  569.                   if (precision == X_PRECISION)
  570.                     *lp++ = 1 << (LITTLENUM_NUMBER_OF_BITS - 1);
  571. #endif
  572.                   while (lp < words_end)
  573.                     *lp++ = 0;
  574.                 }
  575.             }
  576.           else
  577.             *lp += 1;
  578.         }
  579.  
  580.       return return_value;
  581.     }
  582.   else if ((unsigned long) exponent_4 > mask[exponent_bits]
  583.            || (! TC_LARGEST_EXPONENT_IS_NORMAL (precision)
  584.                && (unsigned long) exponent_4 == mask[exponent_bits]))
  585.     {
  586.       /* Exponent overflow.  Lose immediately.  */
  587.  
  588.       /* We leave return_value alone: admit we read the
  589.          number, but return a floating exception
  590.          because we can't encode the number.  */
  591.       make_invalid_floating_point_number (words);
  592.       return return_value;
  593.     }
  594.   else
  595.     {
  596.       word1 |= (exponent_4 << ((LITTLENUM_NUMBER_OF_BITS - 1) - exponent_bits))
  597.         | next_bits ((LITTLENUM_NUMBER_OF_BITS - 1) - exponent_bits);
  598.     }
  599.  
  600.   *lp++ = word1;
  601.  
  602.   /* X_PRECISION is special: on the 68k, it has 16 bits of zero in the
  603.      middle.  Either way, it is then followed by a 1 bit.  */
  604.   if (exponent_bits == 15 && precision == X_PRECISION)
  605.     {
  606. #ifdef TC_M68K
  607.       *lp++ = 0;
  608. #endif
  609.       *lp++ = (1 << (LITTLENUM_NUMBER_OF_BITS - 1)
  610.                | next_bits (LITTLENUM_NUMBER_OF_BITS - 1));
  611.     }
  612.  
  613.   /* The rest of the words are just mantissa bits.  */
  614.   while (lp < words_end)
  615.     *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS);
  616.  
  617.   if (next_bits (1))
  618.     {
  619.       unsigned long carry;
  620.       /* Since the NEXT bit is a 1, round UP the mantissa.
  621.          The cunning design of these hidden-1 floats permits
  622.          us to let the mantissa overflow into the exponent, and
  623.          it 'does the right thing'. However, we lose if the
  624.          highest-order bit of the lowest-order word flips.
  625.          Is that clear?  */
  626.  
  627.       /* #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2)
  628.          Please allow at least 1 more bit in carry than is in a LITTLENUM.
  629.          We need that extra bit to hold a carry during a LITTLENUM carry
  630.          propagation. Another extra bit (kept 0) will assure us that we
  631.          don't get a sticky sign bit after shifting right, and that
  632.          permits us to propagate the carry without any masking of bits.
  633.          #endif */
  634.       for (carry = 1, lp--; carry; lp--)
  635.         {
  636.           carry = *lp + carry;
  637.           *lp = carry;
  638.           carry >>= LITTLENUM_NUMBER_OF_BITS;
  639.           if (lp == words)
  640.             break;
  641.         }
  642.       if (precision == X_PRECISION && exponent_bits == 15)
  643.         {
  644.           /* Extended precision numbers have an explicit integer bit
  645.              that we may have to restore.  */
  646.           if (lp == words)
  647.             {
  648. #ifdef TC_M68K
  649.               /* On the m68k there is a gap of 16 bits.  We must
  650.                  explicitly propagate the carry into the exponent.  */
  651.               words[0] += words[1];
  652.               words[1] = 0;
  653.               lp++;
  654. #endif
  655.               /* Put back the integer bit.  */
  656.               lp[1] |= 1 << (LITTLENUM_NUMBER_OF_BITS - 1);
  657.             }
  658.         }
  659.       if ((word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1)))
  660.         {
  661.           /* We leave return_value alone: admit we read the number,
  662.              but return a floating exception because we can't encode
  663.              the number.  */
  664.           *words &= ~(1 << (LITTLENUM_NUMBER_OF_BITS - 1));
  665.         }
  666.     }
  667.   return return_value;
  668. }
  669.  
  670. #ifdef TEST
  671. char *
  672. print_gen (gen)
  673.      FLONUM_TYPE *gen;
  674. {
  675.   FLONUM_TYPE f;
  676.   LITTLENUM_TYPE arr[10];
  677.   double dv;
  678.   float fv;
  679.   static char sbuf[40];
  680.  
  681.   if (gen)
  682.     {
  683.       f = generic_floating_point_number;
  684.       generic_floating_point_number = *gen;
  685.     }
  686.   gen_to_words (&arr[0], 4, 11);
  687.   memcpy (&dv, &arr[0], sizeof (double));
  688.   sprintf (sbuf, "%x %x %x %x %.14G   ", arr[0], arr[1], arr[2], arr[3], dv);
  689.   gen_to_words (&arr[0], 2, 8);
  690.   memcpy (&fv, &arr[0], sizeof (float));
  691.   sprintf (sbuf + strlen (sbuf), "%x %x %.12g\n", arr[0], arr[1], fv);
  692.  
  693.   if (gen)
  694.     generic_floating_point_number = f;
  695.  
  696.   return (sbuf);
  697. }
  698. #endif
  699.  
  700. extern const char FLT_CHARS[];
  701. #define MAX_LITTLENUMS 6
  702.  
  703. /* This is a utility function called from various tc-*.c files.  It
  704.    is here in order to reduce code duplication.
  705.    
  706.    Turn a string at input_line_pointer into a floating point constant
  707.    of type TYPE (a character found in the FLT_CHARS macro), and store
  708.    it as LITTLENUMS in the bytes buffer LITP.  The number of chars
  709.    emitted is stored in *SIZEP.  BIG_WORDIAN is TRUE if the littlenums
  710.    should be emitted most significant littlenum first.
  711.  
  712.    An error message is returned, or a NULL pointer if everything went OK.  */
  713.  
  714. char *
  715. ieee_md_atof (int type,
  716.               char *litP,
  717.               int *sizeP,
  718.               bfd_boolean big_wordian)
  719. {
  720.   LITTLENUM_TYPE words[MAX_LITTLENUMS];
  721.   LITTLENUM_TYPE *wordP;
  722.   char *t;
  723.   int prec = 0;
  724.  
  725.   if (strchr (FLT_CHARS, type) != NULL)
  726.     {
  727.       switch (type)
  728.         {
  729.         case 'f':
  730.         case 'F':
  731.         case 's':
  732.         case 'S':
  733.           prec = F_PRECISION;
  734.           break;
  735.  
  736.         case 'd':
  737.         case 'D':
  738.         case 'r':
  739.         case 'R':
  740.           prec = D_PRECISION;
  741.           break;
  742.  
  743.         case 't':
  744.         case 'T':
  745.           prec = X_PRECISION;
  746.           type = 'x';           /* This is what atof_ieee() understands.  */
  747.           break;
  748.  
  749.         case 'x':
  750.         case 'X':
  751.         case 'p':
  752.         case 'P':
  753. #ifdef TC_M68K
  754.           /* Note: on the m68k there is a gap of 16 bits (one littlenum)
  755.              between the exponent and mantissa.  Hence the precision is
  756.              6 and not 5.  */
  757.           prec = P_PRECISION + 1;
  758. #else
  759.           prec = P_PRECISION;
  760. #endif
  761.           break;
  762.  
  763.         default:
  764.           break;
  765.         }
  766.     }
  767.   /* The 'f' and 'd' types are always recognised, even if the target has
  768.      not put them into the FLT_CHARS macro.  This is because the 'f' type
  769.      can come from the .dc.s, .dcb.s, .float or .single pseudo-ops and the
  770.      'd' type from the .dc.d, .dbc.d or .double pseudo-ops.
  771.  
  772.      The 'x' type is not implicitly recongised however, even though it can
  773.      be generated by the .dc.x and .dbc.x pseudo-ops because not all targets
  774.      can support floating point values that big.  ie the target has to
  775.      explicitly allow them by putting them into FLT_CHARS.  */
  776.   else if (type == 'f')
  777.     prec = F_PRECISION;
  778.   else if (type == 'd')
  779.     prec = D_PRECISION;
  780.  
  781.   if (prec == 0)
  782.     {
  783.       *sizeP = 0;
  784.       return _("Unrecognized or unsupported floating point constant");
  785.     }
  786.  
  787.   gas_assert (prec <= MAX_LITTLENUMS);
  788.  
  789.   t = atof_ieee (input_line_pointer, type, words);
  790.   if (t)
  791.     input_line_pointer = t;
  792.  
  793.   *sizeP = prec * sizeof (LITTLENUM_TYPE);
  794.  
  795.   if (big_wordian)
  796.     {
  797.       for (wordP = words; prec --;)
  798.         {
  799.           md_number_to_chars (litP, (valueT) (* wordP ++), sizeof (LITTLENUM_TYPE));
  800.           litP += sizeof (LITTLENUM_TYPE);
  801.         }
  802.     }
  803.   else
  804.     {
  805.       for (wordP = words + prec; prec --;)
  806.         {
  807.           md_number_to_chars (litP, (valueT) (* -- wordP), sizeof (LITTLENUM_TYPE));
  808.           litP += sizeof (LITTLENUM_TYPE);
  809.         }
  810.     }
  811.  
  812.   return NULL;
  813. }
  814.