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  1. /* atof_ieee.c - turn a Flonum into an IEEE floating point number
  2.    Copyright (C) 1987-2015 Free Software Foundation, Inc.
  3.  
  4.    This file is part of GAS, the GNU Assembler.
  5.  
  6.    GAS is free software; you can redistribute it and/or modify
  7.    it under the terms of the GNU General Public License as published by
  8.    the Free Software Foundation; either version 3, or (at your option)
  9.    any later version.
  10.  
  11.    GAS is distributed in the hope that it will be useful,
  12.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14.    GNU General Public License for more details.
  15.  
  16.    You should have received a copy of the GNU General Public License
  17.    along with GAS; see the file COPYING.  If not, write to the Free
  18.    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  19.    02110-1301, USA.  */
  20.  
  21. #include "as.h"
  22.  
  23. /* Flonums returned here.  */
  24. extern FLONUM_TYPE generic_floating_point_number;
  25.  
  26. extern const char EXP_CHARS[];
  27. /* Precision in LittleNums.  */
  28. /* Don't count the gap in the m68k extended precision format.  */
  29. #define MAX_PRECISION  5
  30. #define F_PRECISION    2
  31. #define D_PRECISION    4
  32. #define X_PRECISION    5
  33. #define P_PRECISION    5
  34.  
  35. /* Length in LittleNums of guard bits.  */
  36. #define GUARD          2
  37.  
  38. #ifndef TC_LARGEST_EXPONENT_IS_NORMAL
  39. #define TC_LARGEST_EXPONENT_IS_NORMAL(PRECISION) 0
  40. #endif
  41.  
  42. static const unsigned long mask[] =
  43. {
  44.   0x00000000,
  45.   0x00000001,
  46.   0x00000003,
  47.   0x00000007,
  48.   0x0000000f,
  49.   0x0000001f,
  50.   0x0000003f,
  51.   0x0000007f,
  52.   0x000000ff,
  53.   0x000001ff,
  54.   0x000003ff,
  55.   0x000007ff,
  56.   0x00000fff,
  57.   0x00001fff,
  58.   0x00003fff,
  59.   0x00007fff,
  60.   0x0000ffff,
  61.   0x0001ffff,
  62.   0x0003ffff,
  63.   0x0007ffff,
  64.   0x000fffff,
  65.   0x001fffff,
  66.   0x003fffff,
  67.   0x007fffff,
  68.   0x00ffffff,
  69.   0x01ffffff,
  70.   0x03ffffff,
  71.   0x07ffffff,
  72.   0x0fffffff,
  73.   0x1fffffff,
  74.   0x3fffffff,
  75.   0x7fffffff,
  76.   0xffffffff,
  77. };
  79. static int bits_left_in_littlenum;
  80. static int littlenums_left;
  81. static LITTLENUM_TYPE *littlenum_pointer;
  82.  
  83. static int
  84. next_bits (int number_of_bits)
  85. {
  86.   int return_value;
  87.  
  88.   if (!littlenums_left)
  89.     return 0;
  90.  
  91.   if (number_of_bits >= bits_left_in_littlenum)
  92.     {
  93.       return_value = mask[bits_left_in_littlenum] & *littlenum_pointer;
  94.       number_of_bits -= bits_left_in_littlenum;
  95.       return_value <<= number_of_bits;
  96.  
  97.       if (--littlenums_left)
  98.         {
  99.           bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits;
  100.           --littlenum_pointer;
  101.           return_value |=
  102.             (*littlenum_pointer >> bits_left_in_littlenum)
  103.             & mask[number_of_bits];
  104.         }
  105.     }
  106.   else
  107.     {
  108.       bits_left_in_littlenum -= number_of_bits;
  109.       return_value =
  110.         mask[number_of_bits] & (*littlenum_pointer >> bits_left_in_littlenum);
  111.     }
  112.   return return_value;
  113. }
  114.  
  115. /* Num had better be less than LITTLENUM_NUMBER_OF_BITS.  */
  116.  
  117. static void
  118. unget_bits (int num)
  119. {
  120.   if (!littlenums_left)
  121.     {
  122.       ++littlenum_pointer;
  123.       ++littlenums_left;
  124.       bits_left_in_littlenum = num;
  125.     }
  126.   else if (bits_left_in_littlenum + num > LITTLENUM_NUMBER_OF_BITS)
  127.     {
  128.       bits_left_in_littlenum =
  129.         num - (LITTLENUM_NUMBER_OF_BITS - bits_left_in_littlenum);
  130.       ++littlenum_pointer;
  131.       ++littlenums_left;
  132.     }
  133.   else
  134.     bits_left_in_littlenum += num;
  135. }
  136.  
  137. static void
  138. make_invalid_floating_point_number (LITTLENUM_TYPE *words)
  139. {
  140.   as_bad (_("cannot create floating-point number"));
  141.   /* Zero the leftmost bit.  */
  142.   words[0] = (LITTLENUM_TYPE) ((unsigned) -1) >> 1;
  143.   words[1] = (LITTLENUM_TYPE) -1;
  144.   words[2] = (LITTLENUM_TYPE) -1;
  145.   words[3] = (LITTLENUM_TYPE) -1;
  146.   words[4] = (LITTLENUM_TYPE) -1;
  147.   words[5] = (LITTLENUM_TYPE) -1;
  148. }
  150. /* Warning: This returns 16-bit LITTLENUMs.  It is up to the caller to
  151.    figure out any alignment problems and to conspire for the
  152.    bytes/word to be emitted in the right order.  Bigendians beware!  */
  153.  
  154. /* Note that atof-ieee always has X and P precisions enabled.  it is up
  155.    to md_atof to filter them out if the target machine does not support
  156.    them.  */
  157.  
  158. /* Returns pointer past text consumed.  */
  159.  
  160. char *
  161. atof_ieee (char *str,                   /* Text to convert to binary.  */
  162.            int what_kind,               /* 'd', 'f', 'x', 'p'.  */
  163.            LITTLENUM_TYPE *words)       /* Build the binary here.  */
  164. {
  165.   /* Extra bits for zeroed low-order bits.
  166.      The 1st MAX_PRECISION are zeroed, the last contain flonum bits.  */
  167.   static LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD];
  168.   char *return_value;
  169.   /* Number of 16-bit words in the format.  */
  170.   int precision;
  171.   long exponent_bits;
  172.   FLONUM_TYPE save_gen_flonum;
  173.  
  174.   /* We have to save the generic_floating_point_number because it
  175.      contains storage allocation about the array of LITTLENUMs where
  176.      the value is actually stored.  We will allocate our own array of
  177.      littlenums below, but have to restore the global one on exit.  */
  178.   save_gen_flonum = generic_floating_point_number;
  179.  
  180.   return_value = str;
  181.   generic_floating_point_number.low = bits + MAX_PRECISION;
  182.   generic_floating_point_number.high = NULL;
  183.   generic_floating_point_number.leader = NULL;
  184.   generic_floating_point_number.exponent = 0;
  185.   generic_floating_point_number.sign = '\0';
  186.  
  187.   /* Use more LittleNums than seems necessary: the highest flonum may
  188.      have 15 leading 0 bits, so could be useless.  */
  189.  
  190.   memset (bits, '\0', sizeof (LITTLENUM_TYPE) * MAX_PRECISION);
  191.  
  192.   switch (what_kind)
  193.     {
  194.     case 'f':
  195.     case 'F':
  196.     case 's':
  197.     case 'S':
  198.       precision = F_PRECISION;
  199.       exponent_bits = 8;
  200.       break;
  201.  
  202.     case 'd':
  203.     case 'D':
  204.     case 'r':
  205.     case 'R':
  206.       precision = D_PRECISION;
  207.       exponent_bits = 11;
  208.       break;
  209.  
  210.     case 'x':
  211.     case 'X':
  212.     case 'e':
  213.     case 'E':
  214.       precision = X_PRECISION;
  215.       exponent_bits = 15;
  216.       break;
  217.  
  218.     case 'p':
  219.     case 'P':
  220.       precision = P_PRECISION;
  221.       exponent_bits = -1;
  222.       break;
  223.  
  224.     default:
  225.       make_invalid_floating_point_number (words);
  226.       return (NULL);
  227.     }
  228.  
  229.   generic_floating_point_number.high
  230.     = generic_floating_point_number.low + precision - 1 + GUARD;
  231.  
  232.   if (atof_generic (&return_value, ".", EXP_CHARS,
  233.                     &generic_floating_point_number))
  234.     {
  235.       make_invalid_floating_point_number (words);
  236.       return NULL;
  237.     }
  238.   gen_to_words (words, precision, exponent_bits);
  239.  
  240.   /* Restore the generic_floating_point_number's storage alloc (and
  241.      everything else).  */
  242.   generic_floating_point_number = save_gen_flonum;
  243.  
  244.   return return_value;
  245. }
  246.  
  247. /* Turn generic_floating_point_number into a real float/double/extended.  */
  248.  
  249. int
  250. gen_to_words (LITTLENUM_TYPE *words, int precision, long exponent_bits)
  251. {
  252.   int return_value = 0;
  253.  
  254.   long exponent_1;
  255.   long exponent_2;
  256.   long exponent_3;
  257.   long exponent_4;
  258.   int exponent_skippage;
  259.   LITTLENUM_TYPE word1;
  260.   LITTLENUM_TYPE *lp;
  261.   LITTLENUM_TYPE *words_end;
  262.  
  263.   words_end = words + precision;
  264. #ifdef TC_M68K
  265.   if (precision == X_PRECISION)
  266.     /* On the m68k the extended precision format has a gap of 16 bits
  267.        between the exponent and the mantissa.  */
  268.     words_end++;
  269. #endif
  270.  
  271.   if (generic_floating_point_number.low > generic_floating_point_number.leader)
  272.     {
  273.       /* 0.0e0 seen.  */
  274.       if (generic_floating_point_number.sign == '+')
  275.         words[0] = 0x0000;
  276.       else
  277.         words[0] = 0x8000;
  278.       memset (&words[1], '\0',
  279.               (words_end - words - 1) * sizeof (LITTLENUM_TYPE));
  280.       return return_value;
  281.     }
  282.  
  283.   /* NaN:  Do the right thing.  */
  284.   if (generic_floating_point_number.sign == 0)
  285.     {
  286.       if (TC_LARGEST_EXPONENT_IS_NORMAL (precision))
  287.         as_warn (_("NaNs are not supported by this target\n"));
  288.       if (precision == F_PRECISION)
  289.         {
  290.           words[0] = 0x7fff;
  291.           words[1] = 0xffff;
  292.         }
  293.       else if (precision == X_PRECISION)
  294.         {
  295. #ifdef TC_M68K
  296.           words[0] = 0x7fff;
  297.           words[1] = 0;
  298.           words[2] = 0xffff;
  299.           words[3] = 0xffff;
  300.           words[4] = 0xffff;
  301.           words[5] = 0xffff;
  302. #else /* ! TC_M68K  */
  303. #ifdef TC_I386
  304.           words[0] = 0xffff;
  305.           words[1] = 0xc000;
  306.           words[2] = 0;
  307.           words[3] = 0;
  308.           words[4] = 0;
  309. #else /* ! TC_I386  */
  310.           abort ();
  311. #endif /* ! TC_I386  */
  312. #endif /* ! TC_M68K  */
  313.         }
  314.       else
  315.         {
  316.           words[0] = 0x7fff;
  317.           words[1] = 0xffff;
  318.           words[2] = 0xffff;
  319.           words[3] = 0xffff;
  320.         }
  321.       return return_value;
  322.     }
  323.   else if (generic_floating_point_number.sign == 'P')
  324.     {
  325.       if (TC_LARGEST_EXPONENT_IS_NORMAL (precision))
  326.         as_warn (_("Infinities are not supported by this target\n"));
  327.  
  328.       /* +INF:  Do the right thing.  */
  329.       if (precision == F_PRECISION)
  330.         {
  331.           words[0] = 0x7f80;
  332.           words[1] = 0;
  333.         }
  334.       else if (precision == X_PRECISION)
  335.         {
  336. #ifdef TC_M68K
  337.           words[0] = 0x7fff;
  338.           words[1] = 0;
  339.           words[2] = 0;
  340.           words[3] = 0;
  341.           words[4] = 0;
  342.           words[5] = 0;
  343. #else /* ! TC_M68K  */
  344. #ifdef TC_I386
  345.           words[0] = 0x7fff;
  346.           words[1] = 0x8000;
  347.           words[2] = 0;
  348.           words[3] = 0;
  349.           words[4] = 0;
  350. #else /* ! TC_I386  */
  351.           abort ();
  352. #endif /* ! TC_I386  */
  353. #endif /* ! TC_M68K  */
  354.         }
  355.       else
  356.         {
  357.           words[0] = 0x7ff0;
  358.           words[1] = 0;
  359.           words[2] = 0;
  360.           words[3] = 0;
  361.         }
  362.       return return_value;
  363.     }
  364.   else if (generic_floating_point_number.sign == 'N')
  365.     {
  366.       if (TC_LARGEST_EXPONENT_IS_NORMAL (precision))
  367.         as_warn (_("Infinities are not supported by this target\n"));
  368.  
  369.       /* Negative INF.  */
  370.       if (precision == F_PRECISION)
  371.         {
  372.           words[0] = 0xff80;
  373.           words[1] = 0x0;
  374.         }
  375.       else if (precision == X_PRECISION)
  376.         {
  377. #ifdef TC_M68K
  378.           words[0] = 0xffff;
  379.           words[1] = 0;
  380.           words[2] = 0;
  381.           words[3] = 0;
  382.           words[4] = 0;
  383.           words[5] = 0;
  384. #else /* ! TC_M68K  */
  385. #ifdef TC_I386
  386.           words[0] = 0xffff;
  387.           words[1] = 0x8000;
  388.           words[2] = 0;
  389.           words[3] = 0;
  390.           words[4] = 0;
  391. #else /* ! TC_I386  */
  392.           abort ();
  393. #endif /* ! TC_I386  */
  394. #endif /* ! TC_M68K  */
  395.         }
  396.       else
  397.         {
  398.           words[0] = 0xfff0;
  399.           words[1] = 0x0;
  400.           words[2] = 0x0;
  401.           words[3] = 0x0;
  402.         }
  403.       return return_value;
  404.     }
  405.  
  406.   /* The floating point formats we support have:
  407.      Bit 15 is sign bit.
  408.      Bits 14:n are excess-whatever exponent.
  409.      Bits n-1:0 (if any) are most significant bits of fraction.
  410.      Bits 15:0 of the next word(s) are the next most significant bits.
  411.  
  412.      So we need: number of bits of exponent, number of bits of
  413.      mantissa.  */
  414.   bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
  415.   littlenum_pointer = generic_floating_point_number.leader;
  416.   littlenums_left = (1
  417.                      + generic_floating_point_number.leader
  418.                      - generic_floating_point_number.low);
  419.  
  420.   /* Seek (and forget) 1st significant bit.  */
  421.   for (exponent_skippage = 0; !next_bits (1); ++exponent_skippage);
  422.   exponent_1 = (generic_floating_point_number.exponent
  423.                 + generic_floating_point_number.leader
  424.                 + 1
  425.                 - generic_floating_point_number.low);
  426.  
  427.   /* Radix LITTLENUM_RADIX, point just higher than
  428.      generic_floating_point_number.leader.  */
  429.   exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS;
  430.  
  431.   /* Radix 2.  */
  432.   exponent_3 = exponent_2 - exponent_skippage;
  433.  
  434.   /* Forget leading zeros, forget 1st bit.  */
  435.   exponent_4 = exponent_3 + ((1 << (exponent_bits - 1)) - 2);
  436.  
  437.   /* Offset exponent.  */
  438.   lp = words;
  439.  
  440.   /* Word 1.  Sign, exponent and perhaps high bits.  */
  441.   word1 = ((generic_floating_point_number.sign == '+')
  442.            ? 0
  443.            : (1 << (LITTLENUM_NUMBER_OF_BITS - 1)));
  444.  
  445.   /* Assume 2's complement integers.  */
  446.   if (exponent_4 <= 0)
  447.     {
  448.       int prec_bits;
  449.       int num_bits;
  450.  
  451.       unget_bits (1);
  452.       num_bits = -exponent_4;
  453.       prec_bits =
  454.         LITTLENUM_NUMBER_OF_BITS * precision - (exponent_bits + 1 + num_bits);
  455. #ifdef TC_I386
  456.       if (precision == X_PRECISION && exponent_bits == 15)
  457.         {
  458.           /* On the i386 a denormalized extended precision float is
  459.              shifted down by one, effectively decreasing the exponent
  460.              bias by one.  */
  461.           prec_bits -= 1;
  462.           num_bits += 1;
  463.         }
  464. #endif
  465.  
  466.       if (num_bits >= LITTLENUM_NUMBER_OF_BITS - exponent_bits)
  467.         {
  468.           /* Bigger than one littlenum.  */
  469.           num_bits -= (LITTLENUM_NUMBER_OF_BITS - 1) - exponent_bits;
  470.           *lp++ = word1;
  471.           if (num_bits + exponent_bits + 1
  472.               > precision * LITTLENUM_NUMBER_OF_BITS)
  473.             {
  474.               /* Exponent overflow.  */
  475.               make_invalid_floating_point_number (words);
  476.               return return_value;
  477.             }
  478. #ifdef TC_M68K
  479.           if (precision == X_PRECISION && exponent_bits == 15)
  480.             *lp++ = 0;
  481. #endif
  482.           while (num_bits >= LITTLENUM_NUMBER_OF_BITS)
  483.             {
  484.               num_bits -= LITTLENUM_NUMBER_OF_BITS;
  485.               *lp++ = 0;
  486.             }
  487.           if (num_bits)
  488.             *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS - (num_bits));
  489.         }
  490.       else
  491.         {
  492.           if (precision == X_PRECISION && exponent_bits == 15)
  493.             {
  494.               *lp++ = word1;
  495. #ifdef TC_M68K
  496.               *lp++ = 0;
  497. #endif
  498.               *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS - num_bits);
  499.             }
  500.           else
  501.             {
  502.               word1 |= next_bits ((LITTLENUM_NUMBER_OF_BITS - 1)
  503.                                   - (exponent_bits + num_bits));
  504.               *lp++ = word1;
  505.             }
  506.         }
  507.       while (lp < words_end)
  508.         *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS);
  509.  
  510.       /* Round the mantissa up, but don't change the number.  */
  511.       if (next_bits (1))
  512.         {
  513.           --lp;
  514.           if (prec_bits >= LITTLENUM_NUMBER_OF_BITS)
  515.             {
  516.               int n = 0;
  517.               int tmp_bits;
  518.  
  519.               n = 0;
  520.               tmp_bits = prec_bits;
  521.               while (tmp_bits > LITTLENUM_NUMBER_OF_BITS)
  522.                 {
  523.                   if (lp[n] != (LITTLENUM_TYPE) - 1)
  524.                     break;
  525.                   --n;
  526.                   tmp_bits -= LITTLENUM_NUMBER_OF_BITS;
  527.                 }
  528.               if (tmp_bits > LITTLENUM_NUMBER_OF_BITS
  529.                   || (lp[n] & mask[tmp_bits]) != mask[tmp_bits]
  530.                   || (prec_bits != (precision * LITTLENUM_NUMBER_OF_BITS
  531.                                     - exponent_bits - 1)
  532. #ifdef TC_I386
  533.                       /* An extended precision float with only the integer
  534.                          bit set would be invalid.  That must be converted
  535.                          to the smallest normalized number.  */
  536.                       && !(precision == X_PRECISION
  537.                            && prec_bits == (precision * LITTLENUM_NUMBER_OF_BITS
  538.                                             - exponent_bits - 2))
  539. #endif
  540.                       ))
  541.                 {
  542.                   unsigned long carry;
  543.  
  544.                   for (carry = 1; carry && (lp >= words); lp--)
  545.                     {
  546.                       carry = *lp + carry;
  547.                       *lp = carry;
  548.                       carry >>= LITTLENUM_NUMBER_OF_BITS;
  549.                     }
  550.                 }
  551.               else
  552.                 {
  553.                   /* This is an overflow of the denormal numbers.  We
  554.                      need to forget what we have produced, and instead
  555.                      generate the smallest normalized number.  */
  556.                   lp = words;
  557.                   word1 = ((generic_floating_point_number.sign == '+')
  558.                            ? 0
  559.                            : (1 << (LITTLENUM_NUMBER_OF_BITS - 1)));
  560.                   word1 |= (1
  561.                             << ((LITTLENUM_NUMBER_OF_BITS - 1)
  562.                                 - exponent_bits));
  563.                   *lp++ = word1;
  564. #ifdef TC_I386
  565.                   /* Set the integer bit in the extended precision format.
  566.                      This cannot happen on the m68k where the mantissa
  567.                      just overflows into the integer bit above.  */
  568.                   if (precision == X_PRECISION)
  569.                     *lp++ = 1 << (LITTLENUM_NUMBER_OF_BITS - 1);
  570. #endif
  571.                   while (lp < words_end)
  572.                     *lp++ = 0;
  573.                 }
  574.             }
  575.           else
  576.             *lp += 1;
  577.         }
  578.  
  579.       return return_value;
  580.     }
  581.   else if ((unsigned long) exponent_4 > mask[exponent_bits]
  582.            || (! TC_LARGEST_EXPONENT_IS_NORMAL (precision)
  583.                && (unsigned long) exponent_4 == mask[exponent_bits]))
  584.     {
  585.       /* Exponent overflow.  Lose immediately.  */
  586.  
  587.       /* We leave return_value alone: admit we read the
  588.          number, but return a floating exception
  589.          because we can't encode the number.  */
  590.       make_invalid_floating_point_number (words);
  591.       return return_value;
  592.     }
  593.   else
  594.     {
  595.       word1 |= (exponent_4 << ((LITTLENUM_NUMBER_OF_BITS - 1) - exponent_bits))
  596.         | next_bits ((LITTLENUM_NUMBER_OF_BITS - 1) - exponent_bits);
  597.     }
  598.  
  599.   *lp++ = word1;
  600.  
  601.   /* X_PRECISION is special: on the 68k, it has 16 bits of zero in the
  602.      middle.  Either way, it is then followed by a 1 bit.  */
  603.   if (exponent_bits == 15 && precision == X_PRECISION)
  604.     {
  605. #ifdef TC_M68K
  606.       *lp++ = 0;
  607. #endif
  608.       *lp++ = (1 << (LITTLENUM_NUMBER_OF_BITS - 1)
  609.                | next_bits (LITTLENUM_NUMBER_OF_BITS - 1));
  610.     }
  611.  
  612.   /* The rest of the words are just mantissa bits.  */
  613.   while (lp < words_end)
  614.     *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS);
  615.  
  616.   if (next_bits (1))
  617.     {
  618.       unsigned long carry;
  619.       /* Since the NEXT bit is a 1, round UP the mantissa.
  620.          The cunning design of these hidden-1 floats permits
  621.          us to let the mantissa overflow into the exponent, and
  622.          it 'does the right thing'. However, we lose if the
  623.          highest-order bit of the lowest-order word flips.
  624.          Is that clear?  */
  625.  
  626.       /* #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2)
  627.          Please allow at least 1 more bit in carry than is in a LITTLENUM.
  628.          We need that extra bit to hold a carry during a LITTLENUM carry
  629.          propagation. Another extra bit (kept 0) will assure us that we
  630.          don't get a sticky sign bit after shifting right, and that
  631.          permits us to propagate the carry without any masking of bits.
  632.          #endif */
  633.       for (carry = 1, lp--; carry; lp--)
  634.         {
  635.           carry = *lp + carry;
  636.           *lp = carry;
  637.           carry >>= LITTLENUM_NUMBER_OF_BITS;
  638.           if (lp == words)
  639.             break;
  640.         }
  641.       if (precision == X_PRECISION && exponent_bits == 15)
  642.         {
  643.           /* Extended precision numbers have an explicit integer bit
  644.              that we may have to restore.  */
  645.           if (lp == words)
  646.             {
  647. #ifdef TC_M68K
  648.               /* On the m68k there is a gap of 16 bits.  We must
  649.                  explicitly propagate the carry into the exponent.  */
  650.               words[0] += words[1];
  651.               words[1] = 0;
  652.               lp++;
  653. #endif
  654.               /* Put back the integer bit.  */
  655.               lp[1] |= 1 << (LITTLENUM_NUMBER_OF_BITS - 1);
  656.             }
  657.         }
  658.       if ((word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1)))
  659.         {
  660.           /* We leave return_value alone: admit we read the number,
  661.              but return a floating exception because we can't encode
  662.              the number.  */
  663.           *words &= ~(1 << (LITTLENUM_NUMBER_OF_BITS - 1));
  664.         }
  665.     }
  666.   return return_value;
  667. }
  668.  
  669. #ifdef TEST
  670. char *
  671. print_gen (gen)
  672.      FLONUM_TYPE *gen;
  673. {
  674.   FLONUM_TYPE f;
  675.   LITTLENUM_TYPE arr[10];
  676.   double dv;
  677.   float fv;
  678.   static char sbuf[40];
  679.  
  680.   if (gen)
  681.     {
  682.       f = generic_floating_point_number;
  683.       generic_floating_point_number = *gen;
  684.     }
  685.   gen_to_words (&arr[0], 4, 11);
  686.   memcpy (&dv, &arr[0], sizeof (double));
  687.   sprintf (sbuf, "%x %x %x %x %.14G   ", arr[0], arr[1], arr[2], arr[3], dv);
  688.   gen_to_words (&arr[0], 2, 8);
  689.   memcpy (&fv, &arr[0], sizeof (float));
  690.   sprintf (sbuf + strlen (sbuf), "%x %x %.12g\n", arr[0], arr[1], fv);
  691.  
  692.   if (gen)
  693.     generic_floating_point_number = f;
  694.  
  695.   return (sbuf);
  696. }
  697. #endif
  698.  
  699. extern const char FLT_CHARS[];
  700. #define MAX_LITTLENUMS 6
  701.  
  702. /* This is a utility function called from various tc-*.c files.  It
  703.    is here in order to reduce code duplication.
  704.  
  705.    Turn a string at input_line_pointer into a floating point constant
  706.    of type TYPE (a character found in the FLT_CHARS macro), and store
  707.    it as LITTLENUMS in the bytes buffer LITP.  The number of chars
  708.    emitted is stored in *SIZEP.  BIG_WORDIAN is TRUE if the littlenums
  709.    should be emitted most significant littlenum first.
  710.  
  711.    An error message is returned, or a NULL pointer if everything went OK.  */
  712.  
  713. char *
  714. ieee_md_atof (int type,
  715.               char *litP,
  716.               int *sizeP,
  717.               bfd_boolean big_wordian)
  718. {
  719.   LITTLENUM_TYPE words[MAX_LITTLENUMS];
  720.   LITTLENUM_TYPE *wordP;
  721.   char *t;
  722.   int prec = 0;
  723.  
  724.   if (strchr (FLT_CHARS, type) != NULL)
  725.     {
  726.       switch (type)
  727.         {
  728.         case 'f':
  729.         case 'F':
  730.         case 's':
  731.         case 'S':
  732.           prec = F_PRECISION;
  733.           break;
  734.  
  735.         case 'd':
  736.         case 'D':
  737.         case 'r':
  738.         case 'R':
  739.           prec = D_PRECISION;
  740.           break;
  741.  
  742.         case 't':
  743.         case 'T':
  744.           prec = X_PRECISION;
  745.           type = 'x';           /* This is what atof_ieee() understands.  */
  746.           break;
  747.  
  748.         case 'x':
  749.         case 'X':
  750.         case 'p':
  751.         case 'P':
  752. #ifdef TC_M68K
  753.           /* Note: on the m68k there is a gap of 16 bits (one littlenum)
  754.              between the exponent and mantissa.  Hence the precision is
  755.              6 and not 5.  */
  756.           prec = P_PRECISION + 1;
  757. #else
  758.           prec = P_PRECISION;
  759. #endif
  760.           break;
  761.  
  762.         default:
  763.           break;
  764.         }
  765.     }
  766.   /* The 'f' and 'd' types are always recognised, even if the target has
  767.      not put them into the FLT_CHARS macro.  This is because the 'f' type
  768.      can come from the .dc.s, .dcb.s, .float or .single pseudo-ops and the
  769.      'd' type from the .dc.d, .dbc.d or .double pseudo-ops.
  770.  
  771.      The 'x' type is not implicitly recongised however, even though it can
  772.      be generated by the .dc.x and .dbc.x pseudo-ops because not all targets
  773.      can support floating point values that big.  ie the target has to
  774.      explicitly allow them by putting them into FLT_CHARS.  */
  775.   else if (type == 'f')
  776.     prec = F_PRECISION;
  777.   else if (type == 'd')
  778.     prec = D_PRECISION;
  779.  
  780.   if (prec == 0)
  781.     {
  782.       *sizeP = 0;
  783.       return _("Unrecognized or unsupported floating point constant");
  784.     }
  785.  
  786.   gas_assert (prec <= MAX_LITTLENUMS);
  787.  
  788.   t = atof_ieee (input_line_pointer, type, words);
  789.   if (t)
  790.     input_line_pointer = t;
  791.  
  792.   *sizeP = prec * sizeof (LITTLENUM_TYPE);
  793.  
  794.   if (big_wordian)
  795.     {
  796.       for (wordP = words; prec --;)
  797.         {
  798.           md_number_to_chars (litP, (valueT) (* wordP ++), sizeof (LITTLENUM_TYPE));
  799.           litP += sizeof (LITTLENUM_TYPE);
  800.         }
  801.     }
  802.   else
  803.     {
  804.       for (wordP = words + prec; prec --;)
  805.         {
  806.           md_number_to_chars (litP, (valueT) (* -- wordP), sizeof (LITTLENUM_TYPE));
  807.           litP += sizeof (LITTLENUM_TYPE);
  808.         }
  809.     }
  810.  
  811.   return NULL;
  812. }
  813.