patch-2.3.16 linux/arch/ppc/math-emu/udivmodti4.c

• Lines: 192
• Date: Tue Aug 31 11:36:43 1999
• Orig file: v2.3.15/linux/arch/ppc/math-emu/udivmodti4.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.15/linux/arch/ppc/math-emu/udivmodti4.c linux/arch/ppc/math-emu/udivmodti4.c
@@ -0,0 +1,191 @@
+/* This has so very few changes over libgcc2's __udivmoddi4 it isn't funny.  */
+
+#include "soft-fp.h"
+
+#undef count_leading_zeros
+#define count_leading_zeros  __FP_CLZ
+
+void
+_fp_udivmodti4(_FP_W_TYPE q[2], _FP_W_TYPE r[2],
+	       _FP_W_TYPE n1, _FP_W_TYPE n0,
+	       _FP_W_TYPE d1, _FP_W_TYPE d0)
+{
+  _FP_W_TYPE q0, q1, r0, r1;
+  _FP_I_TYPE b, bm;
+
+  if (d1 == 0)
+    {
+#if !UDIV_NEEDS_NORMALIZATION
+      if (d0 > n1)
+	{
+	  /* 0q = nn / 0D */
+
+	  udiv_qrnnd (q0, n0, n1, n0, d0);
+	  q1 = 0;
+
+	  /* Remainder in n0.  */
+	}
+      else
+	{
+	  /* qq = NN / 0d */
+
+	  if (d0 == 0)
+	    d0 = 1 / d0;	/* Divide intentionally by zero.  */
+
+	  udiv_qrnnd (q1, n1, 0, n1, d0);
+	  udiv_qrnnd (q0, n0, n1, n0, d0);
+
+	  /* Remainder in n0.  */
+	}
+
+      r0 = n0;
+      r1 = 0;
+
+#else /* UDIV_NEEDS_NORMALIZATION */
+
+      if (d0 > n1)
+	{
+	  /* 0q = nn / 0D */
+
+	  count_leading_zeros (bm, d0);
+
+	  if (bm != 0)
+	    {
+	      /* Normalize, i.e. make the most significant bit of the
+		 denominator set.  */
+
+	      d0 = d0 << bm;
+	      n1 = (n1 << bm) | (n0 >> (_FP_W_TYPE_SIZE - bm));
+	      n0 = n0 << bm;
+	    }
+
+	  udiv_qrnnd (q0, n0, n1, n0, d0);
+	  q1 = 0;
+
+	  /* Remainder in n0 >> bm.  */
+	}
+      else
+	{
+	  /* qq = NN / 0d */
+
+	  if (d0 == 0)
+	    d0 = 1 / d0;	/* Divide intentionally by zero.  */
+
+	  count_leading_zeros (bm, d0);
+
+	  if (bm == 0)
+	    {
+	      /* From (n1 >= d0) /\ (the most significant bit of d0 is set),
+		 conclude (the most significant bit of n1 is set) /\ (the
+		 leading quotient digit q1 = 1).
+
+		 This special case is necessary, not an optimization.
+		 (Shifts counts of SI_TYPE_SIZE are undefined.)  */
+
+	      n1 -= d0;
+	      q1 = 1;
+	    }
+	  else
+	    {
+	      _FP_W_TYPE n2;
+
+	      /* Normalize.  */
+
+	      b = _FP_W_TYPE_SIZE - bm;
+
+	      d0 = d0 << bm;
+	      n2 = n1 >> b;
+	      n1 = (n1 << bm) | (n0 >> b);
+	      n0 = n0 << bm;
+
+	      udiv_qrnnd (q1, n1, n2, n1, d0);
+	    }
+
+	  /* n1 != d0...  */
+
+	  udiv_qrnnd (q0, n0, n1, n0, d0);
+
+	  /* Remainder in n0 >> bm.  */
+	}
+
+      r0 = n0 >> bm;
+      r1 = 0;
+#endif /* UDIV_NEEDS_NORMALIZATION */
+    }
+  else
+    {
+      if (d1 > n1)
+	{
+	  /* 00 = nn / DD */
+
+	  q0 = 0;
+	  q1 = 0;
+
+	  /* Remainder in n1n0.  */
+	  r0 = n0;
+	  r1 = n1;
+	}
+      else
+	{
+	  /* 0q = NN / dd */
+
+	  count_leading_zeros (bm, d1);
+	  if (bm == 0)
+	    {
+	      /* From (n1 >= d1) /\ (the most significant bit of d1 is set),
+		 conclude (the most significant bit of n1 is set) /\ (the
+		 quotient digit q0 = 0 or 1).
+
+		 This special case is necessary, not an optimization.  */
+
+	      /* The condition on the next line takes advantage of that
+		 n1 >= d1 (true due to program flow).  */
+	      if (n1 > d1 || n0 >= d0)
+		{
+		  q0 = 1;
+		  sub_ddmmss (n1, n0, n1, n0, d1, d0);
+		}
+	      else
+		q0 = 0;
+
+	      q1 = 0;
+
+	      r0 = n0;
+	      r1 = n1;
+	    }
+	  else
+	    {
+	      _FP_W_TYPE m1, m0, n2;
+
+	      /* Normalize.  */
+
+	      b = _FP_W_TYPE_SIZE - bm;
+
+	      d1 = (d1 << bm) | (d0 >> b);
+	      d0 = d0 << bm;
+	      n2 = n1 >> b;
+	      n1 = (n1 << bm) | (n0 >> b);
+	      n0 = n0 << bm;
+
+	      udiv_qrnnd (q0, n1, n2, n1, d1);
+	      umul_ppmm (m1, m0, q0, d0);
+
+	      if (m1 > n1 || (m1 == n1 && m0 > n0))
+		{
+		  q0--;
+		  sub_ddmmss (m1, m0, m1, m0, d1, d0);
+		}
+
+	      q1 = 0;
+
+	      /* Remainder in (n1n0 - m1m0) >> bm.  */
+	      sub_ddmmss (n1, n0, n1, n0, m1, m0);
+	      r0 = (n1 << b) | (n0 >> bm);
+	      r1 = n1 >> bm;
+	    }
+	}
+    }
+
+  q[0] = q0; q[1] = q1;
+  r[0] = r0, r[1] = r1;
+}