fpu/softfloat-parts-addsub.c.inc

   1 /*
   2  * Floating point arithmetic implementation
   3  *
   4  * The code in this source file is derived from release 2a of the SoftFloat
   5  * IEC/IEEE Floating-point Arithmetic Package. Those parts of the code (and
   6  * some later contributions) are provided under that license, as detailed below.
   7  * It has subsequently been modified by contributors to the QEMU Project,
   8  * so some portions are provided under:
   9  *  the SoftFloat-2a license
  10  *  the BSD license
  11  *  GPL-v2-or-later
  12  *
  13  * Any future contributions to this file after December 1st 2014 will be
  14  * taken to be licensed under the Softfloat-2a license unless specifically
  15  * indicated otherwise.
  16  */
  17
  18 static void partsN(add_normal)(FloatPartsN *a, FloatPartsN *b)
  19 {
  20     int exp_diff = a->exp - b->exp;
  21
  22     if (exp_diff > 0) {
  23         frac_shrjam(b, exp_diff);
  24     } else if (exp_diff < 0) {
  25         frac_shrjam(a, -exp_diff);
  26         a->exp = b->exp;
  27     }
  28
  29     if (frac_add(a, a, b)) {
  30         frac_shrjam(a, 1);
  31         a->frac_hi |= DECOMPOSED_IMPLICIT_BIT;
  32         a->exp += 1;
  33     }
  34 }
  35
  36 static bool partsN(sub_normal)(FloatPartsN *a, FloatPartsN *b)
  37 {
  38     int exp_diff = a->exp - b->exp;
  39     int shift;
  40
  41     if (exp_diff > 0) {
  42         frac_shrjam(b, exp_diff);
  43         frac_sub(a, a, b);
  44     } else if (exp_diff < 0) {
  45         a->exp = b->exp;
  46         a->sign ^= 1;
  47         frac_shrjam(a, -exp_diff);
  48         frac_sub(a, b, a);
  49     } else if (frac_sub(a, a, b)) {
  50         /* Overflow means that A was less than B. */
  51         frac_neg(a);
  52         a->sign ^= 1;
  53     }
  54
  55     shift = frac_normalize(a);
  56     if (likely(shift < N)) {
  57         a->exp -= shift;
  58         return true;
  59     }
  60     a->cls = float_class_zero;
  61     return false;
  62 }