formatting tweaks

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@12390 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 838 insertions, 0 deletions

diff --git a/gcc/floatlib.c b/gcc/floatlib.c
new file mode 100644
index 00000000000..bdcdf57ddd0
--- /dev/null
+++ b/gcc/floatlib.c
@@ -0,0 +1,838 @@
+/*
+** libgcc support for software floating point.
+** Copyright (C) 1991 by Pipeline Associates, Inc.  All rights reserved.
+** Permission is granted to do *anything* you want with this file,
+** commercial or otherwise, provided this message remains intact.  So there!
+** I would appreciate receiving any updates/patches/changes that anyone
+** makes, and am willing to be the repository for said changes (am I
+** making a big mistake?).
+
+Warning! Only single-precision is actually implemented.  This file
+won't really be much use until double-precision is supported.
+
+However, once that is done, this file might eventually become a
+replacement for libgcc1.c.  It might also make possible
+cross-compilation for an IEEE target machine from a non-IEEE
+host such as a VAX.
+
+If you'd like to work on completing this, please talk to rms@gnu.ai.mit.edu.
+
+
+**
+** Pat Wood
+** Pipeline Associates, Inc.
+** pipeline!phw@motown.com or
+** sun!pipeline!phw or
+** uunet!motown!pipeline!phw
+**
+** 05/01/91 -- V1.0 -- first release to gcc mailing lists
+** 05/04/91 -- V1.1 -- added float and double prototypes and return values
+**                  -- fixed problems with adding and subtracting zero
+**                  -- fixed rounding in truncdfsf2
+**                  -- fixed SWAP define and tested on 386
+*/
+
+/*
+** The following are routines that replace the libgcc soft floating point
+** routines that are called automatically when -msoft-float is selected.
+** The support single and double precision IEEE format, with provisions
+** for byte-swapped machines (tested on 386).  Some of the double-precision
+** routines work at full precision, but most of the hard ones simply punt
+** and call the single precision routines, producing a loss of accuracy.
+** long long support is not assumed or included.
+** Overall accuracy is close to IEEE (actually 68882) for single-precision
+** arithmetic.  I think there may still be a 1 in 1000 chance of a bit
+** being rounded the wrong way during a multiply.  I'm not fussy enough to
+** bother with it, but if anyone is, knock yourself out.
+**
+** Efficiency has only been addressed where it was obvious that something
+** would make a big difference.  Anyone who wants to do this right for
+** best speed should go in and rewrite in assembler.
+**
+** I have tested this only on a 68030 workstation and 386/ix integrated
+** in with -msoft-float.
+*/
+
+/* the following deal with IEEE single-precision numbers */
+#define D_PHANTOM_BIT   0x00100000
+#define EXCESS		126
+#define SIGNBIT		0x80000000
+#define HIDDEN		(1 << 23)
+#define SIGN(fp)	((fp) & SIGNBIT)
+#define EXP(fp)		(((fp) >> 23) & 0xFF)
+#define MANT(fp)	(((fp) & 0x7FFFFF) | HIDDEN)
+#define PACK(s,e,m)	((s) | ((e) << 23) | (m))
+
+/* the following deal with IEEE double-precision numbers */
+#define EXCESSD		1022
+#define HIDDEND		(1 << 20)
+#define EXPD(fp)	(((fp.l.upper) >> 20) & 0x7FF)
+#define SIGND(fp)	((fp.l.upper) & SIGNBIT)
+#define MANTD(fp)	(((((fp.l.upper) & 0xFFFFF) | HIDDEND) << 10) | \
+				(fp.l.lower >> 22))
+
+/* define SWAP for 386/960 reverse-byte-order brain-damaged CPUs */
+union double_long
+  {
+    double d;
+#ifdef SWAP
+    struct {
+      unsigned long lower;
+      long upper;
+    } l;
+#else
+    struct {
+      long upper;
+      unsigned long lower;
+    } l;
+#endif
+  };
+
+union float_long
+  {
+    float f;
+    long l;
+  };
+
+   struct _ieee {
+#ifdef SWAP
+      unsigned mantissa2 : 32;
+      unsigned mantissa1 : 20;
+      unsigned exponent  : 11;
+      unsigned sign      : 1;
+#else
+      unsigned exponent  : 11;
+      unsigned sign      : 1;
+      unsigned mantissa2 : 32;
+      unsigned mantissa1 : 20;
+#endif
+   };
+
+   union _doubleu {
+      double d;
+      struct _ieee ieee;
+#ifdef SWAP
+      struct {
+         unsigned long lower;
+         long upper;
+      } l;
+#else
+      struct {
+         long upper;
+         unsigned long lower;
+      } l;
+#endif
+   };
+
+/* add two floats */
+
+float
+__addsf3 (float a1, float a2)
+{
+  register long mant1, mant2;
+  register union float_long fl1, fl2;
+  register int exp1, exp2;
+  int sign = 0;
+
+  fl1.f = a1;
+  fl2.f = a2;
+
+  /* check for zero args */
+  if (!fl1.l)
+    return (fl2.f);
+  if (!fl2.l)
+    return (fl1.f);
+
+  exp1 = EXP (fl1.l);
+  exp2 = EXP (fl2.l);
+
+  if (exp1 > exp2 + 25)
+    return (fl1.l);
+  if (exp2 > exp1 + 25)
+    return (fl2.l);
+
+  /* do everything in excess precision so's we can round later */
+  mant1 = MANT (fl1.l) << 6;
+  mant2 = MANT (fl2.l) << 6;
+
+  if (SIGN (fl1.l))
+    mant1 = -mant1;
+  if (SIGN (fl2.l))
+    mant2 = -mant2;
+
+  if (exp1 > exp2)
+    {
+      mant2 >>= exp1 - exp2;
+    }
+  else
+    {
+      mant1 >>= exp2 - exp1;
+      exp1 = exp2;
+    }
+  mant1 += mant2;
+
+  if (mant1 < 0)
+    {
+      mant1 = -mant1;
+      sign = SIGNBIT;
+    }
+  else if (!mant1)
+    return (0);
+
+  /* normalize up */
+  while (!(mant1 & 0xE0000000))
+    {
+      mant1 <<= 1;
+      exp1--;
+    }
+
+  /* normalize down? */
+  if (mant1 & (1 << 30))
+    {
+      mant1 >>= 1;
+      exp1++;
+    }
+
+  /* round to even */
+  mant1 += (mant1 & 0x40) ? 0x20 : 0x1F;
+
+  /* normalize down? */
+  if (mant1 & (1 << 30))
+    {
+      mant1 >>= 1;
+      exp1++;
+    }
+
+  /* lose extra precision */
+  mant1 >>= 6;
+
+  /* turn off hidden bit */
+  mant1 &= ~HIDDEN;
+
+  /* pack up and go home */
+  fl1.l = PACK (sign, exp1, mant1);
+  return (fl1.f);
+}
+
+/* subtract two floats */
+
+float
+__subsf3 (float a1, float a2)
+{
+  register union float_long fl1, fl2;
+
+  fl1.f = a1;
+  fl2.f = a2;
+
+  /* check for zero args */
+  if (!fl2.l)
+    return (fl1.f);
+  if (!fl1.l)
+    return (-fl2.f);
+
+  /* twiddle sign bit and add */
+  fl2.l ^= SIGNBIT;
+  return __addsf3 (a1, fl2.f);
+}
+
+/* compare two floats */
+
+long
+__cmpsf2 (float a1, float a2)
+{
+  register union float_long fl1, fl2;
+
+  fl1.f = a1;
+  fl2.f = a2;
+
+  if (SIGN (fl1.l) && SIGN (fl2.l))
+    {
+      fl1.l ^= SIGNBIT;
+      fl2.l ^= SIGNBIT;
+    }
+  if (fl1.l < fl2.l)
+    return (-1);
+  if (fl1.l > fl2.l)
+    return (1);
+  return (0);
+}
+
+/* multiply two floats */
+
+float
+__mulsf3 (float a1, float a2)
+{
+  register union float_long fl1, fl2;
+  register unsigned long result;
+  register int exp;
+  int sign;
+
+  fl1.f = a1;
+  fl2.f = a2;
+
+  if (!fl1.l || !fl2.l)
+    return (0);
+
+  /* compute sign and exponent */
+  sign = SIGN (fl1.l) ^ SIGN (fl2.l);
+  exp = EXP (fl1.l) - EXCESS;
+  exp += EXP (fl2.l);
+
+  fl1.l = MANT (fl1.l);
+  fl2.l = MANT (fl2.l);
+
+  /* the multiply is done as one 16x16 multiply and two 16x8 multiples */
+  result = (fl1.l >> 8) * (fl2.l >> 8);
+  result += ((fl1.l & 0xFF) * (fl2.l >> 8)) >> 8;
+  result += ((fl2.l & 0xFF) * (fl1.l >> 8)) >> 8;
+
+  if (result & 0x80000000)
+    {
+      /* round */
+      result += 0x80;
+      result >>= 8;
+    }
+  else
+    {
+      /* round */
+      result += 0x40;
+      result >>= 7;
+      exp--;
+    }
+
+  result &= ~HIDDEN;
+
+  /* pack up and go home */
+  fl1.l = PACK (sign, exp, result);
+  return (fl1.f);
+}
+
+/* divide two floats */
+
+float
+__divsf3 (float a1, float a2)
+{
+  register union float_long fl1, fl2;
+  register int result;
+  register int mask;
+  register int exp, sign;
+
+  fl1.f = a1;
+  fl2.f = a2;
+
+  /* subtract exponents */
+  exp = EXP (fl1.l) - EXP (fl2.l) + EXCESS;
+
+  /* compute sign */
+  sign = SIGN (fl1.l) ^ SIGN (fl2.l);
+
+  /* divide by zero??? */
+  if (!fl2.l)
+    /* return NaN or -NaN */
+    return (sign ? 0xFFFFFFFF : 0x7FFFFFFF);
+
+  /* numerator zero??? */
+  if (!fl1.l)
+    return (0);
+
+  /* now get mantissas */
+  fl1.l = MANT (fl1.l);
+  fl2.l = MANT (fl2.l);
+
+  /* this assures we have 25 bits of precision in the end */
+  if (fl1.l < fl2.l)
+    {
+      fl1.l <<= 1;
+      exp--;
+    }
+
+  /* now we perform repeated subtraction of fl2.l from fl1.l */
+  mask = 0x1000000;
+  result = 0;
+  while (mask)
+    {
+      if (fl1.l >= fl2.l)
+	{
+	  result |= mask;
+	  fl1.l -= fl2.l;
+	}
+      fl1.l <<= 1;
+      mask >>= 1;
+    }
+
+  /* round */
+  result += 1;
+
+  /* normalize down */
+  exp++;
+  result >>= 1;
+
+  result &= ~HIDDEN;
+
+  /* pack up and go home */
+  fl1.l = PACK (sign, exp, result);
+  return (fl1.f);
+}
+
+/* convert int to double */
+
+double
+__floatsidf (register long a1)
+{
+  register int sign = 0, exp = 31 + EXCESSD;
+  union double_long dl;
+
+  if (!a1)
+    {
+      dl.l.upper = dl.l.lower = 0;
+      return (dl.d);
+    }
+
+  if (a1 < 0)
+    {
+      sign = SIGNBIT;
+      a1 = -a1;
+    }
+
+  while (a1 < 0x1000000)
+    {
+      a1 <<= 4;
+      exp -= 4;
+    }
+
+  while (a1 < 0x40000000)
+    {
+      a1 <<= 1;
+      exp--;
+    }
+
+  /* pack up and go home */
+  dl.l.upper = sign;
+  dl.l.upper |= exp << 20;
+  dl.l.upper |= (a1 >> 10) & ~HIDDEND;
+  dl.l.lower = a1 << 22;
+
+  return (dl.d);
+}
+
+/* negate a float */
+
+float
+__negsf2 (float a1)
+{
+  register union float_long fl1;
+
+  fl1.f = a1;
+  if (!fl1.l)
+    return (0);
+
+  fl1.l ^= SIGNBIT;
+  return (fl1.f);
+}
+
+/* negate a double */
+
+double
+__negdf2 (double a1)
+{
+  register union double_long dl1;
+
+  dl1.d = a1;
+
+  if (!dl1.l.upper && !dl1.l.lower)
+      return (dl1.d);
+
+  dl1.l.upper ^= SIGNBIT;
+  return (dl1.d);
+}
+
+/* convert float to double */
+
+double
+__extendsfdf2 (float a1)
+{
+  register union float_long fl1;
+  register union double_long dl;
+  register int exp;
+
+  fl1.f = a1;
+
+  if (!fl1.l)
+    {
+      dl.l.upper = dl.l.lower = 0;
+      return (dl.d);
+    }
+
+  dl.l.upper = SIGN (fl1.l);
+  exp = EXP (fl1.l) - EXCESS + EXCESSD;
+  dl.l.upper |= exp << 20;
+  dl.l.upper |= (MANT (fl1.l) & ~HIDDEN) >> 3;
+  dl.l.lower = MANT (fl1.l) << 29;
+
+  return (dl.d);
+}
+
+/* convert double to float */
+
+float
+__truncdfsf2 (double a1)
+{
+  register int exp;
+  register long mant;
+  register union float_long fl;
+  register union double_long dl1;
+
+  dl1.d = a1;
+
+  if (!dl1.l.upper && !dl1.l.lower)
+    return (0);
+
+  exp = EXPD (dl1) - EXCESSD + EXCESS;
+
+  /* shift double mantissa 6 bits so we can round */
+  mant = MANTD (dl1) >> 6;
+
+  /* now round and shift down */
+  mant += 1;
+  mant >>= 1;
+
+  /* did the round overflow? */
+  if (mant & 0xFF000000)
+    {
+      mant >>= 1;
+      exp++;
+    }
+
+  mant &= ~HIDDEN;
+
+  /* pack up and go home */
+  fl.l = PACK (SIGND (dl1), exp, mant);
+  return (fl.f);
+}
+
+/* compare two doubles */
+
+long
+__cmpdf2 (double a1, double a2)
+{
+  register union double_long dl1, dl2;
+
+  dl1.d = a1;
+  dl2.d = a2;
+
+  if (SIGND (dl1) && SIGND (dl2))
+    {
+      dl1.l.upper ^= SIGNBIT;
+      dl2.l.upper ^= SIGNBIT;
+    }
+  if (dl1.l.upper < dl2.l.upper)
+    return (-1);
+  if (dl1.l.upper > dl2.l.upper)
+    return (1);
+  if (dl1.l.lower < dl2.l.lower)
+    return (-1);
+  if (dl1.l.lower > dl2.l.lower)
+    return (1);
+  return (0);
+}
+
+/* convert double to int */
+
+long
+__fixdfsi (double a1)
+{
+  register union double_long dl1;
+  register int exp;
+  register long l;
+
+  dl1.d = a1;
+
+  if (!dl1.l.upper && !dl1.l.lower)
+    return (0);
+
+  exp = EXPD (dl1) - EXCESSD - 31;
+  l = MANTD (dl1);
+
+  if (exp > 0)
+    return (0x7FFFFFFF | SIGND (dl1)); /* largest integer */
+
+  /* shift down until exp = 0 or l = 0 */
+  if (exp < 0 && exp > -32 && l)
+    l >>= -exp;
+  else
+    return (0);
+
+  return (SIGND (dl1) ? -l : l);
+}
+
+/* convert double to unsigned int */
+
+unsigned
+long __fixunsdfsi (double a1)
+{
+  register union double_long dl1;
+  register int exp;
+  register unsigned long l;
+
+  dl1.d = a1;
+
+  if (!dl1.l.upper && !dl1.l.lower)
+    return (0);
+
+  exp = EXPD (dl1) - EXCESSD - 32;
+  l = (((((dl1.l.upper) & 0xFFFFF) | HIDDEND) << 11) | (dl1.l.lower >> 21));
+
+  if (exp > 0)
+    return (0xFFFFFFFF);	/* largest integer */
+
+  /* shift down until exp = 0 or l = 0 */
+  if (exp < 0 && exp > -32 && l)
+    l >>= -exp;
+  else
+    return (0);
+
+  return (l);
+}
+
+/* For now, the hard double-precision routines simply
+   punt and do it in single */
+/* addtwo doubles */
+
+double
+__adddf3 (double a1, double a2)
+{
+  return ((float) a1 + (float) a2);
+}
+
+/* subtract two doubles */
+
+double
+__subdf3 (double a1, double a2)
+{
+  return ((float) a1 - (float) a2);
+}
+
+/* multiply two doubles */
+
+double
+__muldf3 (double a1, double a2)
+{
+  return ((float) a1 * (float) a2);
+}
+
+/*
+ *
+ * Name:   Barrett Richardson
+ * E-mail: barrett@iglou.com
+ * When:   Thu Dec 15 10:31:11 EST 1994
+ *
+ *    callable function:
+ *
+ *       double __divdf3(double a1, double a2);
+ *
+ *       Does software divide of a1 / a2.
+ *
+ *       Based largely on __divsf3() in floatlib.c in the gcc
+ *       distribution.
+ *
+ *    Purpose: To be used in conjunction with the -msoft-float
+ *             option of gcc. You should be able to tack it to the
+ *             end of floatlib.c included in the gcc distribution,
+ *             and delete the __divdf3() already there which just 
+ *             calls the single precision function (or may just
+ *             use the floating point processor with some configurations).
+ *
+ *   You may use this code for whatever your heart desires.
+ */
+
+
+
+
+/*
+ * Compare the the mantissas of two doubles.
+ * Each mantissa is in two longs.
+ * 
+ *   return      1   if x1's mantissa is greater than x2's
+ *              -1   if x1's mantissa is less than x2's
+ *               0   if the two mantissa's are equal.
+ *
+ *   The Mantissas won't fit into a 4 byte word, so they are
+ *   broken up into two parts.
+ *
+ *   This function is used internally by __divdf3()
+ */
+
+int
+__dcmp (long x1m1, long x1m2, long x2m1, long x2m2)
+{
+   if (x1m1 > x2m1)
+      return 1;
+
+   if (x1m1 < x2m1)
+      return -1;
+
+ /*  If the first word in the two mantissas were equal check the second word */
+
+   if (x1m2 > x2m2)
+      return 1;
+
+   if (x1m2 < x2m2)
+      return -1;
+
+   return 0;
+}
+
+
+/* divide two doubles */
+
+double
+__divdf3 (double a1, double a2)
+{
+
+   int  sign,
+        exponent,
+        bit_bucket;
+
+   register unsigned long mantissa1,
+                          mantissa2,
+                          x1m1,
+                          x1m2,
+                          x2m1,
+                          x2m2,
+                          mask;
+
+   union _doubleu x1,
+                  x2,
+                  result;
+
+
+   x1.d = a1;
+   x2.d = a2;
+
+   exponent = x1.ieee.exponent - x2.ieee.exponent + EXCESSD;
+
+   sign = x1.ieee.sign ^ x2.ieee.sign;
+
+   x2.ieee.sign = 0;  /* don't want the sign bit to affect any zero */
+                      /* comparisons when checking for zero divide  */
+
+   if (!x2.l.lower && !x2.l.upper) { /* check for zero divide */
+      result.l.lower = 0x0;
+      if (sign)
+         result.l.upper = 0xFFF00000;   /* negative infinity */
+      else
+         result.l.upper = 0x7FF00000;   /* positive infinity */
+      return result.d;
+   }
+
+   if (!x1.l.upper && !x1.l.lower)  /* check for 0.0 numerator */
+      return (0.0);
+
+   x1m1 = x1.ieee.mantissa1 | D_PHANTOM_BIT;  /* turn on phantom bit */
+   x1m2 = x1.ieee.mantissa2;
+
+   x2m1 = x2.ieee.mantissa1 | D_PHANTOM_BIT;  /* turn on phantom bit */
+   x2m2 = x2.ieee.mantissa2;
+
+   if (__dcmp(x1m1,x1m2,x2m1,x2m2) < 0) {
+
+   /* if x1's mantissa is less than x2's shift it left one and decrement */
+   /* the exponent to accomodate the change in the mantissa              */
+
+      x1m1 <<= 1;               /*                          */
+      bit_bucket = x1m2 >> 31;  /*  Shift mantissa left one */
+      x1m1 |= bit_bucket;       /*                          */
+      x1m2 <<= 1;               /*                          */
+
+      exponent--;
+   }
+
+
+   mantissa1 = 0;
+   mantissa2 = 0;
+
+
+  /* Get the first part of the results mantissa using successive */
+  /* subtraction.                                                */
+
+   mask = 0x00200000;
+   while (mask) {
+
+      if (__dcmp(x1m1,x1m2,x2m1,x2m2) >= 0) {
+
+     /* subtract x2's mantissa from x1's */
+
+         mantissa1 |= mask;   /* turn on a bit in the result */
+
+         if (x2m2 > x1m2)
+            x1m1--;
+         x1m2 -= x2m2; 
+         x1m1 -= x2m1;
+      }
+
+      x1m1 <<= 1;               /*                          */
+      bit_bucket = x1m2 >> 31;  /*  Shift mantissa left one */
+      x1m1 |= bit_bucket;       /*                          */
+      x1m2 <<= 1;               /*                          */
+
+      mask >>= 1;
+   }
+
+  /* Get the second part of the results mantissa using successive */
+  /* subtraction.                                                 */
+
+   mask = 0x80000000;
+   while (mask) {
+
+      if (__dcmp(x1m1,x1m2,x2m1,x2m2) >= 0) {
+
+     /* subtract x2's mantissa from x1's */
+
+         mantissa2 |= mask;   /* turn on a bit in the result */
+
+         if (x2m2 > x1m2)
+            x1m1--;
+         x1m2 -= x2m2; 
+         x1m1 -= x2m1;
+      }
+      x1m1 <<= 1;               /*                          */
+      bit_bucket = x1m2 >> 31;  /*  Shift mantissa left one */
+      x1m1 |= bit_bucket;       /*                          */
+      x1m2 <<= 1;               /*                          */
+
+      mask >>= 1;
+   }
+
+  /* round up by adding 1 to mantissa */
+
+   if (mantissa2 == 0xFFFFFFFF) {  /* check for over flow */
+
+   /* spill if overflow */
+
+      mantissa2 = 0;
+      mantissa1++;
+   }
+   else
+      mantissa2++;
+
+   exponent++;   /* increment exponent (mantissa must be shifted right */
+                 /* also)                                              */
+
+ /* shift mantissa right one and assume a phantom bit (which really gives */
+ /* 53 bits of precision in the mantissa)                                 */
+
+   mantissa2 >>= 1;
+   bit_bucket = mantissa1 & 1;
+   mantissa2 |= (bit_bucket << 31);
+   mantissa1 >>= 1;
+
+  /* put all the info into the result */
+
+   result.ieee.exponent  = exponent;
+   result.ieee.sign      = sign;
+   result.ieee.mantissa1 = mantissa1;
+   result.ieee.mantissa2 = mantissa2;
+
+
+   return result.d;
+}