1 files changed, 229 insertions, 0 deletions

diff --git a/arch/i386/math-emu/poly_atan.c b/arch/i386/math-emu/poly_atan.c
new file mode 100644
index 000000000000..82f702952f69
--- /dev/null
+++ b/arch/i386/math-emu/poly_atan.c
@@ -0,0 +1,229 @@
+/*---------------------------------------------------------------------------+
+ |  poly_atan.c                                                              |
+ |                                                                           |
+ | Compute the arctan of a FPU_REG, using 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 "status_w.h"
+#include "control_w.h"
+#include "poly.h"
+
+
+#define HIPOWERon       6       /* odd poly, negative terms */
+static const unsigned long long oddnegterms[HIPOWERon] =
+{
+  0x0000000000000000LL, /* Dummy (not for - 1.0) */
+  0x015328437f756467LL,
+  0x0005dda27b73dec6LL,
+  0x0000226bf2bfb91aLL,
+  0x000000ccc439c5f7LL,
+  0x0000000355438407LL
+} ;
+
+#define HIPOWERop       6       /* odd poly, positive terms */
+static const unsigned long long oddplterms[HIPOWERop] =
+{
+/*  0xaaaaaaaaaaaaaaabLL,  transferred to fixedpterm[] */
+  0x0db55a71875c9ac2LL,
+  0x0029fce2d67880b0LL,
+  0x0000dfd3908b4596LL,
+  0x00000550fd61dab4LL,
+  0x0000001c9422b3f9LL,
+  0x000000003e3301e1LL
+};
+
+static const unsigned long long denomterm = 0xebd9b842c5c53a0eLL;
+
+static const Xsig fixedpterm = MK_XSIG(0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa);
+
+static const Xsig pi_signif = MK_XSIG(0xc90fdaa2, 0x2168c234, 0xc4c6628b);
+
+
+/*--- poly_atan() -----------------------------------------------------------+
+ |                                                                           |
+ +---------------------------------------------------------------------------*/
+void    poly_atan(FPU_REG *st0_ptr, u_char st0_tag,
+                  FPU_REG *st1_ptr, u_char st1_tag)
+{
+  u_char        transformed, inverted,
+                sign1, sign2;
+  int           exponent;
+  long int      dummy_exp;
+  Xsig          accumulator, Numer, Denom, accumulatore, argSignif,
+                argSq, argSqSq;
+  u_char        tag;
+  
+  sign1 = getsign(st0_ptr);
+  sign2 = getsign(st1_ptr);
+  if ( st0_tag == TAG_Valid )
+    {
+      exponent = exponent(st0_ptr);
+    }
+  else
+    {
+      /* This gives non-compatible stack contents... */
+      FPU_to_exp16(st0_ptr, st0_ptr);
+      exponent = exponent16(st0_ptr);
+    }
+  if ( st1_tag == TAG_Valid )
+    {
+      exponent -= exponent(st1_ptr);
+    }
+  else
+    {
+      /* This gives non-compatible stack contents... */
+      FPU_to_exp16(st1_ptr, st1_ptr);
+      exponent -= exponent16(st1_ptr);
+    }
+
+  if ( (exponent < 0) || ((exponent == 0) &&
+                          ((st0_ptr->sigh < st1_ptr->sigh) ||
+                           ((st0_ptr->sigh == st1_ptr->sigh) &&
+                            (st0_ptr->sigl < st1_ptr->sigl))) ) )
+    {
+      inverted = 1;
+      Numer.lsw = Denom.lsw = 0;
+      XSIG_LL(Numer) = significand(st0_ptr);
+      XSIG_LL(Denom) = significand(st1_ptr);
+    }
+  else
+    {
+      inverted = 0;
+      exponent = -exponent;
+      Numer.lsw = Denom.lsw = 0;
+      XSIG_LL(Numer) = significand(st1_ptr);
+      XSIG_LL(Denom) = significand(st0_ptr);
+     }
+  div_Xsig(&Numer, &Denom, &argSignif);
+  exponent += norm_Xsig(&argSignif);
+
+  if ( (exponent >= -1)
+      || ((exponent == -2) && (argSignif.msw > 0xd413ccd0)) )
+    {
+      /* The argument is greater than sqrt(2)-1 (=0.414213562...) */
+      /* Convert the argument by an identity for atan */
+      transformed = 1;
+
+      if ( exponent >= 0 )
+        {
+#ifdef PARANOID
+          if ( !( (exponent == 0) && 
+                 (argSignif.lsw == 0) && (argSignif.midw == 0) &&
+                 (argSignif.msw == 0x80000000) ) )
+            {
+              EXCEPTION(EX_INTERNAL|0x104);  /* There must be a logic error */
+              return;
+            }
+#endif /* PARANOID */
+          argSignif.msw = 0;   /* Make the transformed arg -> 0.0 */
+        }
+      else
+        {
+          Numer.lsw = Denom.lsw = argSignif.lsw;
+          XSIG_LL(Numer) = XSIG_LL(Denom) = XSIG_LL(argSignif);
+
+          if ( exponent < -1 )
+            shr_Xsig(&Numer, -1-exponent);
+          negate_Xsig(&Numer);
+      
+          shr_Xsig(&Denom, -exponent);
+          Denom.msw |= 0x80000000;
+      
+          div_Xsig(&Numer, &Denom, &argSignif);
+
+          exponent = -1 + norm_Xsig(&argSignif);
+        }
+    }
+  else
+    {
+      transformed = 0;
+    }
+
+  argSq.lsw = argSignif.lsw; argSq.midw = argSignif.midw;
+  argSq.msw = argSignif.msw;
+  mul_Xsig_Xsig(&argSq, &argSq);
+  
+  argSqSq.lsw = argSq.lsw; argSqSq.midw = argSq.midw; argSqSq.msw = argSq.msw;
+  mul_Xsig_Xsig(&argSqSq, &argSqSq);
+
+  accumulatore.lsw = argSq.lsw;
+  XSIG_LL(accumulatore) = XSIG_LL(argSq);
+
+  shr_Xsig(&argSq, 2*(-1-exponent-1));
+  shr_Xsig(&argSqSq, 4*(-1-exponent-1));
+
+  /* Now have argSq etc with binary point at the left
+     .1xxxxxxxx */
+
+  /* Do the basic fixed point polynomial evaluation */
+  accumulator.msw = accumulator.midw = accumulator.lsw = 0;
+  polynomial_Xsig(&accumulator, &XSIG_LL(argSqSq),
+                   oddplterms, HIPOWERop-1);
+  mul64_Xsig(&accumulator, &XSIG_LL(argSq));
+  negate_Xsig(&accumulator);
+  polynomial_Xsig(&accumulator, &XSIG_LL(argSqSq), oddnegterms, HIPOWERon-1);
+  negate_Xsig(&accumulator);
+  add_two_Xsig(&accumulator, &fixedpterm, &dummy_exp);
+
+  mul64_Xsig(&accumulatore, &denomterm);
+  shr_Xsig(&accumulatore, 1 + 2*(-1-exponent));
+  accumulatore.msw |= 0x80000000;
+
+  div_Xsig(&accumulator, &accumulatore, &accumulator);
+
+  mul_Xsig_Xsig(&accumulator, &argSignif);
+  mul_Xsig_Xsig(&accumulator, &argSq);
+
+  shr_Xsig(&accumulator, 3);
+  negate_Xsig(&accumulator);
+  add_Xsig_Xsig(&accumulator, &argSignif);
+
+  if ( transformed )
+    {
+      /* compute pi/4 - accumulator */
+      shr_Xsig(&accumulator, -1-exponent);
+      negate_Xsig(&accumulator);
+      add_Xsig_Xsig(&accumulator, &pi_signif);
+      exponent = -1;
+    }
+
+  if ( inverted )
+    {
+      /* compute pi/2 - accumulator */
+      shr_Xsig(&accumulator, -exponent);
+      negate_Xsig(&accumulator);
+      add_Xsig_Xsig(&accumulator, &pi_signif);
+      exponent = 0;
+    }
+
+  if ( sign1 )
+    {
+      /* compute pi - accumulator */
+      shr_Xsig(&accumulator, 1 - exponent);
+      negate_Xsig(&accumulator);
+      add_Xsig_Xsig(&accumulator, &pi_signif);
+      exponent = 1;
+    }
+
+  exponent += round_Xsig(&accumulator);
+
+  significand(st1_ptr) = XSIG_LL(accumulator);
+  setexponent16(st1_ptr, exponent);
+
+  tag = FPU_round(st1_ptr, 1, 0, FULL_PRECISION, sign2);
+  FPU_settagi(1, tag);
+
+  set_precision_flag_up();  /* We do not really know if up or down,
+                               use this as the default. */
+
+}