1 files changed, 156 insertions, 0 deletions

diff --git a/arch/i386/math-emu/poly_2xm1.c b/arch/i386/math-emu/poly_2xm1.c
new file mode 100644
index 00000000000..9766ad5e974
--- /dev/null
+++ b/arch/i386/math-emu/poly_2xm1.c
@@ -0,0 +1,156 @@
+/*---------------------------------------------------------------------------+
+ |  poly_2xm1.c                                                              |
+ |                                                                           |
+ | Function to compute 2^x-1 by a polynomial approximation.                  |
+ |                                                                           |
+ | Copyright (C) 1992,1993,1994,1997                                         |
+ |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
+ |                  E-mail   billm@suburbia.net                              |
+ |                                                                           |
+ |                                                                           |
+ +---------------------------------------------------------------------------*/
+
+#include "exception.h"
+#include "reg_constant.h"
+#include "fpu_emu.h"
+#include "fpu_system.h"
+#include "control_w.h"
+#include "poly.h"
+
+
+#define HIPOWER 11
+static const unsigned long long lterms[HIPOWER] =
+{
+  0x0000000000000000LL,  /* This term done separately as 12 bytes */
+  0xf5fdeffc162c7543LL,
+  0x1c6b08d704a0bfa6LL,
+  0x0276556df749cc21LL,
+  0x002bb0ffcf14f6b8LL,
+  0x0002861225ef751cLL,
+  0x00001ffcbfcd5422LL,
+  0x00000162c005d5f1LL,
+  0x0000000da96ccb1bLL,
+  0x0000000078d1b897LL,
+  0x000000000422b029LL
+};
+
+static const Xsig hiterm = MK_XSIG(0xb17217f7, 0xd1cf79ab, 0xc8a39194);
+
+/* Four slices: 0.0 : 0.25 : 0.50 : 0.75 : 1.0,
+   These numbers are 2^(1/4), 2^(1/2), and 2^(3/4)
+ */
+static const Xsig shiftterm0 = MK_XSIG(0, 0, 0);
+static const Xsig shiftterm1 = MK_XSIG(0x9837f051, 0x8db8a96f, 0x46ad2318);
+static const Xsig shiftterm2 = MK_XSIG(0xb504f333, 0xf9de6484, 0x597d89b3);
+static const Xsig shiftterm3 = MK_XSIG(0xd744fcca, 0xd69d6af4, 0x39a68bb9);
+
+static const Xsig *shiftterm[] = { &shiftterm0, &shiftterm1,
+                                     &shiftterm2, &shiftterm3 };
+
+
+/*--- poly_2xm1() -----------------------------------------------------------+
+ | Requires st(0) which is TAG_Valid and < 1.                                |
+ +---------------------------------------------------------------------------*/
+int     poly_2xm1(u_char sign, FPU_REG *arg, FPU_REG *result)
+{
+  long int              exponent, shift;
+  unsigned long long    Xll;
+  Xsig                  accumulator, Denom, argSignif;
+  u_char                tag;
+
+  exponent = exponent16(arg);
+
+#ifdef PARANOID
+  if ( exponent >= 0 )          /* Don't want a |number| >= 1.0 */
+    {
+      /* Number negative, too large, or not Valid. */
+      EXCEPTION(EX_INTERNAL|0x127);
+      return 1;
+    }
+#endif /* PARANOID */
+
+  argSignif.lsw = 0;
+  XSIG_LL(argSignif) = Xll = significand(arg);
+
+  if ( exponent == -1 )
+    {
+      shift = (argSignif.msw & 0x40000000) ? 3 : 2;
+      /* subtract 0.5 or 0.75 */
+      exponent -= 2;
+      XSIG_LL(argSignif) <<= 2;
+      Xll <<= 2;
+    }
+  else if ( exponent == -2 )
+    {
+      shift = 1;
+      /* subtract 0.25 */
+      exponent--;
+      XSIG_LL(argSignif) <<= 1;
+      Xll <<= 1;
+    }
+  else
+    shift = 0;
+
+  if ( exponent < -2 )
+    {
+      /* Shift the argument right by the required places. */
+      if ( FPU_shrx(&Xll, -2-exponent) >= 0x80000000U )
+        Xll++;  /* round up */
+    }
+
+  accumulator.lsw = accumulator.midw = accumulator.msw = 0;
+  polynomial_Xsig(&accumulator, &Xll, lterms, HIPOWER-1);
+  mul_Xsig_Xsig(&accumulator, &argSignif);
+  shr_Xsig(&accumulator, 3);
+
+  mul_Xsig_Xsig(&argSignif, &hiterm);   /* The leading term */
+  add_two_Xsig(&accumulator, &argSignif, &exponent);
+
+  if ( shift )
+    {
+      /* The argument is large, use the identity:
+         f(x+a) = f(a) * (f(x) + 1) - 1;
+         */
+      shr_Xsig(&accumulator, - exponent);
+      accumulator.msw |= 0x80000000;      /* add 1.0 */
+      mul_Xsig_Xsig(&accumulator, shiftterm[shift]);
+      accumulator.msw &= 0x3fffffff;      /* subtract 1.0 */
+      exponent = 1;
+    }
+
+  if ( sign != SIGN_POS )
+    {
+      /* The argument is negative, use the identity:
+             f(-x) = -f(x) / (1 + f(x))
+         */
+      Denom.lsw = accumulator.lsw;
+      XSIG_LL(Denom) = XSIG_LL(accumulator);
+      if ( exponent < 0 )
+        shr_Xsig(&Denom, - exponent);
+      else if ( exponent > 0 )
+        {
+          /* exponent must be 1 here */
+          XSIG_LL(Denom) <<= 1;
+          if ( Denom.lsw & 0x80000000 )
+            XSIG_LL(Denom) |= 1;
+          (Denom.lsw) <<= 1;
+        }
+      Denom.msw |= 0x80000000;      /* add 1.0 */
+      div_Xsig(&accumulator, &Denom, &accumulator);
+    }
+
+  /* Convert to 64 bit signed-compatible */
+  exponent += round_Xsig(&accumulator);
+
+  result = &st(0);
+  significand(result) = XSIG_LL(accumulator);
+  setexponent16(result, exponent);
+
+  tag = FPU_round(result, 1, 0, FULL_PRECISION, sign);
+
+  setsign(result, sign);
+  FPU_settag0(tag);
+
+  return 0;
+
+}