libgcc/soft-fp/bitintpow10.c

   1 /* Software floating-point emulation.
   2    Compute powers of 10 into _BitInt.
   3
   4    Copyright (C) 2023 Free Software Foundation, Inc.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 Under Section 7 of GPL version 3, you are granted additional
  19 permissions described in the GCC Runtime Library Exception, version
  20 3.1, as published by the Free Software Foundation.
  21
  22 You should have received a copy of the GNU General Public License and
  23 a copy of the GCC Runtime Library Exception along with this program;
  24 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  25 <http://www.gnu.org/licenses/>.  */
  26
  27 #include "soft-fp.h"
  28 #include "bitint.h"
  29
  30 #ifdef __BITINT_MAXWIDTH__
  31 # define BIL_VAL(x) ((UBILtype) (x))
  32 # if BIL_TYPE_SIZE == 64
  33 #  define BIL_PAIR(x, y) ((BIL_VAL (x) << 32) | BIL_VAL (y))
  34 #  define BIL_OFF(x, y) (x)
  35 # elif BIL_TYPE_SIZE == 32
  36 #  if __LIBGCC_BITINT_ORDER__ == __ORDER_BIG_ENDIAN__
  37 #   define BIL_PAIR(x, y) BIL_VAL (x), BIL_VAL (y)
  38 #  else
  39 #   define BIL_PAIR(x, y) BIL_VAL (y), BIL_VAL (x)
  40 #  endif
  41 #  define BIL_OFF(x, y) (y)
  42 # else
  43 #  error Unsupported _BitInt limb size
  44 # endif
  45 #if __LIBGCC_BITINT_ORDER__ == __ORDER_BIG_ENDIAN__
  46 # define BIL_SET2(a, b) a, b
  47 # define BIL_SET3(a, b, c) a, b, c
  48 # define BIL_SET4(a, b, c, d) a, b, c, d
  49 # define BIL_SET5(a, b, c, d, e) a, b, c, d, e
  50 # define BIL_SET6(a, b, c, d, e, f) a, b, c, d, e, f
  51 # define BIL_SET7(a, b, c, d, e, f, g) a, b, c, d, e, f, g
  52 # define BIL_SET8(a, b, c, d, e, f, g, h) a, b, c, d, e, f, g, h
  53 # define BIL_SET9(a, b, c, d, e, f, g, h, i) a, b, c, d, e, f, g, h, i
  54 # define BIL_SET10(a, b, c, d, e, f, g, h, i, j) a, b, c, d, e, f, g, h, i, j
  55 # define BIL_SET11(a, b, c, d, e, f, g, h, i, j, k) \
  56   a, b, c, d, e, f, g, h, i, j, k
  57 # define BIL_SET12(a, b, c, d, e, f, g, h, i, j, k, l) \
  58   a, b, c, d, e, f, g, h, i, j, k, l
  59 # define BIL_SET13(a, b, c, d, e, f, g, h, i, j, k, l, m) \
  60   a, b, c, d, e, f, g, h, i, j, k, l, m
  61 # define BIL_SET14(a, b, c, d, e, f, g, h, i, j, k, l, m, n) \
  62   a, b, c, d, e, f, g, h, i, j, k, l, m, n
  63 # define BIL_SET15(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) \
  64   a, b, c, d, e, f, g, h, i, j, k, l, m, n, o
  65 #else
  66 # define BIL_SET2(a, b) b, a
  67 # define BIL_SET3(a, b, c) c, b, a
  68 # define BIL_SET4(a, b, c, d) d, c, b, a
  69 # define BIL_SET5(a, b, c, d, e) e, d, c, b, a
  70 # define BIL_SET6(a, b, c, d, e, f) f, e, d, c, b, a
  71 # define BIL_SET7(a, b, c, d, e, f, g) g, f, e, d, c, b, a
  72 # define BIL_SET8(a, b, c, d, e, f, g, h) h, g, f, e, d, c, b, a
  73 # define BIL_SET9(a, b, c, d, e, f, g, h, i) i, h, g, f, e, d, c, b, a
  74 # define BIL_SET10(a, b, c, d, e, f, g, h, i, j) j, i, h, g, f, e, d, c, b, a
  75 # define BIL_SET11(a, b, c, d, e, f, g, h, i, j, k) \
  76   k, j, i, h, g, f, e, d, c, b, a
  77 # define BIL_SET12(a, b, c, d, e, f, g, h, i, j, k, l) \
  78   l, k, j, i, h, g, f, e, d, c, b, a
  79 # define BIL_SET13(a, b, c, d, e, f, g, h, i, j, k, l, m) \
  80   m, l, k, j, i, h, g, f, e, d, c, b, a
  81 # define BIL_SET14(a, b, c, d, e, f, g, h, i, j, k, l, m, n) \
  82   n, m, l, k, j, i, h, g, f, e, d, c, b, a
  83 # define BIL_SET15(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) \
  84   o, n, m, l, k, j, i, h, g, f, e, d, c, b, a
  85 #endif
  86
  87 #include "bitintpow10.h"
  88
  89 /* Set r (_BitInt limbs with rprec bits) to pow10 (n),
  90    where n is in [0, 6111].  Returns number of least significant
  91    limbs with just 0s in it.  */
  92
  93 USItype
  94 __bid_pow10bitint (UBILtype *r, SItype rprec, USItype n)
  95 {
  96   USItype rn = ((USItype) rprec + BIL_TYPE_SIZE - 1) / BIL_TYPE_SIZE;
  97   if (n <= 256)
  98     {
  99       /* No need to multiply anything, just copy it from pow10_limbs
 100          array.  */
 101       USItype low_zeros = (n / 64) * (64 / BIL_TYPE_SIZE);
 102       UBILtype *p = &pow10_limbs[pow10_offs[n]];
 103       USItype cnt = pow10_offs[n + 1] - pow10_offs[n];
 104       if (low_zeros)
 105         __builtin_memset (r + BITINT_END (rn - low_zeros, 0), '\0',
 106                           low_zeros * sizeof (UBILtype));
 107       __builtin_memcpy (r + BITINT_END (rn - low_zeros - cnt, low_zeros),
 108                         p, cnt * sizeof (UBILtype));
 109       if (rn > low_zeros + cnt)
 110         __builtin_memset (r + BITINT_END (0, low_zeros + cnt), '\0',
 111                           (rn - low_zeros - cnt) * sizeof (UBILtype));
 112       return low_zeros;
 113     }
 114   else
 115     {
 116       USItype m = n / 256;
 117       n &= 255;
 118       USItype low_zeros = ((n / 64) + (m * 4)) * (64 / BIL_TYPE_SIZE);
 119       UBILtype *pm = &pow10_limbs[pow10_offs[m + 255]];
 120       USItype cntm = pow10_offs[m + 256] - pow10_offs[m + 255];
 121       UBILtype *pn = &pow10_limbs[pow10_offs[n]];
 122       USItype cntn = pow10_offs[n + 1] - pow10_offs[n];
 123       if (low_zeros)
 124         __builtin_memset (r + BITINT_END (rn - low_zeros, 0), '\0',
 125                           low_zeros * sizeof (UBILtype));
 126       __mulbitint3 (r + BITINT_END (0, low_zeros),
 127                     rprec - low_zeros * BIL_TYPE_SIZE,
 128                     pm, cntm * BIL_TYPE_SIZE, pn, cntn * BIL_TYPE_SIZE);
 129       return low_zeros;
 130     }
 131 }
 132 #endif