i386: move math-emu

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 374 insertions, 0 deletions

diff --git a/arch/x86/math-emu/reg_add_sub.c b/arch/x86/math-emu/reg_add_sub.c
new file mode 100644
index 0000000..7cd3b37
--- /dev/null
+++ b/arch/x86/math-emu/reg_add_sub.c
@@ -0,0 +1,374 @@
+/*---------------------------------------------------------------------------+
+ |  reg_add_sub.c                                                            |
+ |                                                                           |
+ | Functions to add or subtract two registers and put the result in a third. |
+ |                                                                           |
+ | Copyright (C) 1992,1993,1997                                              |
+ |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
+ |                  E-mail   billm@suburbia.net                              |
+ |                                                                           |
+ |                                                                           |
+ +---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------+
+ |  For each function, the destination may be any FPU_REG, including one of  |
+ | the source FPU_REGs.                                                      |
+ |  Each function returns 0 if the answer is o.k., otherwise a non-zero      |
+ | value is returned, indicating either an exception condition or an         |
+ | internal error.                                                           |
+ +---------------------------------------------------------------------------*/
+
+#include "exception.h"
+#include "reg_constant.h"
+#include "fpu_emu.h"
+#include "control_w.h"
+#include "fpu_system.h"
+
+static
+int add_sub_specials(FPU_REG const *a, u_char taga, u_char signa,
+		     FPU_REG const *b, u_char tagb, u_char signb,
+		     FPU_REG *dest, int deststnr, int control_w);
+
+/*
+  Operates on st(0) and st(n), or on st(0) and temporary data.
+  The destination must be one of the source st(x).
+  */
+int FPU_add(FPU_REG const *b, u_char tagb, int deststnr, int control_w)
+{
+  FPU_REG *a = &st(0);
+  FPU_REG *dest = &st(deststnr);
+  u_char signb = getsign(b);
+  u_char taga = FPU_gettag0();
+  u_char signa = getsign(a);
+  u_char saved_sign = getsign(dest);
+  int diff, tag, expa, expb;
+  
+  if ( !(taga | tagb) )
+    {
+      expa = exponent(a);
+      expb = exponent(b);
+
+    valid_add:
+      /* Both registers are valid */
+      if (!(signa ^ signb))
+	{
+	  /* signs are the same */
+	  tag = FPU_u_add(a, b, dest, control_w, signa, expa, expb);
+	}
+      else
+	{
+	  /* The signs are different, so do a subtraction */
+	  diff = expa - expb;
+	  if (!diff)
+	    {
+	      diff = a->sigh - b->sigh;  /* This works only if the ms bits
+					    are identical. */
+	      if (!diff)
+		{
+		  diff = a->sigl > b->sigl;
+		  if (!diff)
+		    diff = -(a->sigl < b->sigl);
+		}
+	    }
+      
+	  if (diff > 0)
+	    {
+	      tag = FPU_u_sub(a, b, dest, control_w, signa, expa, expb);
+	    }
+	  else if ( diff < 0 )
+	    {
+	      tag = FPU_u_sub(b, a, dest, control_w, signb, expb, expa);
+	    }
+	  else
+	    {
+	      FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr);
+	      /* sign depends upon rounding mode */
+	      setsign(dest, ((control_w & CW_RC) != RC_DOWN)
+		      ? SIGN_POS : SIGN_NEG);
+	      return TAG_Zero;
+	    }
+	}
+
+      if ( tag < 0 )
+	{
+	  setsign(dest, saved_sign);
+	  return tag;
+	}
+      FPU_settagi(deststnr, tag);
+      return tag;
+    }
+
+  if ( taga == TAG_Special )
+    taga = FPU_Special(a);
+  if ( tagb == TAG_Special )
+    tagb = FPU_Special(b);
+
+  if ( ((taga == TAG_Valid) && (tagb == TW_Denormal))
+	    || ((taga == TW_Denormal) && (tagb == TAG_Valid))
+	    || ((taga == TW_Denormal) && (tagb == TW_Denormal)) )
+    {
+      FPU_REG x, y;
+
+      if ( denormal_operand() < 0 )
+	return FPU_Exception;
+
+      FPU_to_exp16(a, &x);
+      FPU_to_exp16(b, &y);
+      a = &x;
+      b = &y;
+      expa = exponent16(a);
+      expb = exponent16(b);
+      goto valid_add;
+    }
+
+  if ( (taga == TW_NaN) || (tagb == TW_NaN) )
+    {
+      if ( deststnr == 0 )
+	return real_2op_NaN(b, tagb, deststnr, a);
+      else
+	return real_2op_NaN(a, taga, deststnr, a);
+    }
+
+  return add_sub_specials(a, taga, signa, b, tagb, signb,
+			  dest, deststnr, control_w);
+}
+
+
+/* Subtract b from a.  (a-b) -> dest */
+int FPU_sub(int flags, int rm, int control_w)
+{
+  FPU_REG const *a, *b;
+  FPU_REG *dest;
+  u_char taga, tagb, signa, signb, saved_sign, sign;
+  int diff, tag = 0, expa, expb, deststnr;
+
+  a = &st(0);
+  taga = FPU_gettag0();
+
+  deststnr = 0;
+  if ( flags & LOADED )
+    {
+      b = (FPU_REG *)rm;
+      tagb = flags & 0x0f;
+    }
+  else
+    {
+      b = &st(rm);
+      tagb = FPU_gettagi(rm);
+
+      if ( flags & DEST_RM )
+	deststnr = rm;
+    }
+
+  signa = getsign(a);
+  signb = getsign(b);
+
+  if ( flags & REV )
+    {
+      signa ^= SIGN_NEG;
+      signb ^= SIGN_NEG;
+    }
+
+  dest = &st(deststnr);
+  saved_sign = getsign(dest);
+
+  if ( !(taga | tagb) )
+    {
+      expa = exponent(a);
+      expb = exponent(b);
+
+    valid_subtract:
+      /* Both registers are valid */
+
+      diff = expa - expb;
+
+      if (!diff)
+	{
+	  diff = a->sigh - b->sigh;  /* Works only if ms bits are identical */
+	  if (!diff)
+	    {
+	      diff = a->sigl > b->sigl;
+	      if (!diff)
+		diff = -(a->sigl < b->sigl);
+	    }
+	}
+
+      switch ( (((int)signa)*2 + signb) / SIGN_NEG )
+	{
+	case 0: /* P - P */
+	case 3: /* N - N */
+	  if (diff > 0)
+	    {
+	      /* |a| > |b| */
+	      tag = FPU_u_sub(a, b, dest, control_w, signa, expa, expb);
+	    }
+	  else if ( diff == 0 )
+	    {
+	      FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr);
+
+	      /* sign depends upon rounding mode */
+	      setsign(dest, ((control_w & CW_RC) != RC_DOWN)
+		? SIGN_POS : SIGN_NEG);
+	      return TAG_Zero;
+	    }
+	  else
+	    {
+	      sign = signa ^ SIGN_NEG;
+	      tag = FPU_u_sub(b, a, dest, control_w, sign, expb, expa);
+	    }
+	  break;
+	case 1: /* P - N */
+	  tag = FPU_u_add(a, b, dest, control_w, SIGN_POS, expa, expb);
+	  break;
+	case 2: /* N - P */
+	  tag = FPU_u_add(a, b, dest, control_w, SIGN_NEG, expa, expb);
+	  break;
+#ifdef PARANOID
+	default:
+	  EXCEPTION(EX_INTERNAL|0x111);
+	  return -1;
+#endif
+	}
+      if ( tag < 0 )
+	{
+	  setsign(dest, saved_sign);
+	  return tag;
+	}
+      FPU_settagi(deststnr, tag);
+      return tag;
+    }
+
+  if ( taga == TAG_Special )
+    taga = FPU_Special(a);
+  if ( tagb == TAG_Special )
+    tagb = FPU_Special(b);
+
+  if ( ((taga == TAG_Valid) && (tagb == TW_Denormal))
+	    || ((taga == TW_Denormal) && (tagb == TAG_Valid))
+	    || ((taga == TW_Denormal) && (tagb == TW_Denormal)) )
+    {
+      FPU_REG x, y;
+
+      if ( denormal_operand() < 0 )
+	return FPU_Exception;
+
+      FPU_to_exp16(a, &x);
+      FPU_to_exp16(b, &y);
+      a = &x;
+      b = &y;
+      expa = exponent16(a);
+      expb = exponent16(b);
+
+      goto valid_subtract;
+    }
+
+  if ( (taga == TW_NaN) || (tagb == TW_NaN) )
+    {
+      FPU_REG const *d1, *d2;
+      if ( flags & REV )
+	{
+	  d1 = b;
+	  d2 = a;
+	}
+      else
+	{
+	  d1 = a;
+	  d2 = b;
+	}
+      if ( flags & LOADED )
+	return real_2op_NaN(b, tagb, deststnr, d1);
+      if ( flags & DEST_RM )
+	return real_2op_NaN(a, taga, deststnr, d2);
+      else
+	return real_2op_NaN(b, tagb, deststnr, d2);
+    }
+
+    return add_sub_specials(a, taga, signa, b, tagb, signb ^ SIGN_NEG,
+			    dest, deststnr, control_w);
+}
+
+
+static
+int add_sub_specials(FPU_REG const *a, u_char taga, u_char signa,
+		     FPU_REG const *b, u_char tagb, u_char signb,
+		     FPU_REG *dest, int deststnr, int control_w)
+{
+  if ( ((taga == TW_Denormal) || (tagb == TW_Denormal))
+       && (denormal_operand() < 0) )
+    return FPU_Exception;
+
+  if (taga == TAG_Zero)
+    {
+      if (tagb == TAG_Zero)
+	{
+	  /* Both are zero, result will be zero. */
+	  u_char different_signs = signa ^ signb;
+
+	  FPU_copy_to_regi(a, TAG_Zero, deststnr);
+	  if ( different_signs )
+	    {
+	      /* Signs are different. */
+	      /* Sign of answer depends upon rounding mode. */
+	      setsign(dest, ((control_w & CW_RC) != RC_DOWN)
+		      ? SIGN_POS : SIGN_NEG);
+	    }
+	  else
+	    setsign(dest, signa);  /* signa may differ from the sign of a. */
+	  return TAG_Zero;
+	}
+      else
+	{
+	  reg_copy(b, dest);
+	  if ( (tagb == TW_Denormal) && (b->sigh & 0x80000000) )
+	    {
+	      /* A pseudoDenormal, convert it. */
+	      addexponent(dest, 1);
+	      tagb = TAG_Valid;
+	    }
+	  else if ( tagb > TAG_Empty )
+	    tagb = TAG_Special;
+	  setsign(dest, signb);  /* signb may differ from the sign of b. */
+	  FPU_settagi(deststnr, tagb);
+	  return tagb;
+	}
+    }
+  else if (tagb == TAG_Zero)
+    {
+      reg_copy(a, dest);
+      if ( (taga == TW_Denormal) && (a->sigh & 0x80000000) )
+	{
+	  /* A pseudoDenormal */
+	  addexponent(dest, 1);
+	  taga = TAG_Valid;
+	}
+      else if ( taga > TAG_Empty )
+	taga = TAG_Special;
+      setsign(dest, signa);  /* signa may differ from the sign of a. */
+      FPU_settagi(deststnr, taga);
+      return taga;
+    }
+  else if (taga == TW_Infinity)
+    {
+      if ( (tagb != TW_Infinity) || (signa == signb) )
+	{
+	  FPU_copy_to_regi(a, TAG_Special, deststnr);
+	  setsign(dest, signa);  /* signa may differ from the sign of a. */
+	  return taga;
+	}
+      /* Infinity-Infinity is undefined. */
+      return arith_invalid(deststnr);
+    }
+  else if (tagb == TW_Infinity)
+    {
+      FPU_copy_to_regi(b, TAG_Special, deststnr);
+      setsign(dest, signb);  /* signb may differ from the sign of b. */
+      return tagb;
+    }
+
+#ifdef PARANOID
+  EXCEPTION(EX_INTERNAL|0x101);
+#endif
+
+  return FPU_Exception;
+}
+