more tahoe code

gas/config/atof-tahoe.c

@@ -0,0 +1,431 @@
+
+/* atof_tahoe.c - turn a string into a Tahoe floating point number
+   Copyright (C) 1987 Free Software Foundation, Inc.
+   */
+
+/* This is really a simplified version of atof_vax.c. I glommed it wholesale
+   and then shaved it down. I don't even know how it works. (Don't you find
+   my honesty refreshing?  bowen@cs.Buffalo.EDU (Devon E Bowen)
+
+   I don't allow uppercase letters in the precision descrpitors. Ie 'f' and
+   'd' are allowed but 'F' and 'D' aren't */
+
+#include "as.h"
+
+/* Precision in LittleNums. */
+#define MAX_PRECISION (4)
+#define D_PRECISION (4)
+#define F_PRECISION (2)
+
+/* Precision in chars. */
+#define D_PRECISION_CHARS (8)
+#define F_PRECISION_CHARS (4)
+
+/* Length in LittleNums of guard bits. */
+#define GUARD (2)
+
+static const long int mask[] =
+{
+  0x00000000,
+  0x00000001,
+  0x00000003,
+  0x00000007,
+  0x0000000f,
+  0x0000001f,
+  0x0000003f,
+  0x0000007f,
+  0x000000ff,
+  0x000001ff,
+  0x000003ff,
+  0x000007ff,
+  0x00000fff,
+  0x00001fff,
+  0x00003fff,
+  0x00007fff,
+  0x0000ffff,
+  0x0001ffff,
+  0x0003ffff,
+  0x0007ffff,
+  0x000fffff,
+  0x001fffff,
+  0x003fffff,
+  0x007fffff,
+  0x00ffffff,
+  0x01ffffff,
+  0x03ffffff,
+  0x07ffffff,
+  0x0fffffff,
+  0x1fffffff,
+  0x3fffffff,
+  0x7fffffff,
+  0xffffffff
+};
+
+
+/* Shared between flonum_gen2tahoe and next_bits */
+static int bits_left_in_littlenum;
+static LITTLENUM_TYPE *littlenum_pointer;
+static LITTLENUM_TYPE *littlenum_end;
+
+#if __STDC__ == 1
+
+int flonum_gen2tahoe (int format_letter, FLONUM_TYPE * f, LITTLENUM_TYPE * words);
+
+#else /* not __STDC__ */
+
+int flonum_gen2tahoe ();
+
+#endif /* not __STDC__ */
+
+
+static int
+next_bits (number_of_bits)
+     int number_of_bits;
+{
+  int return_value;
+
+  if (littlenum_pointer < littlenum_end)
+    return 0;
+  if (number_of_bits >= bits_left_in_littlenum)
+    {
+      return_value = mask[bits_left_in_littlenum] & *littlenum_pointer;
+      number_of_bits -= bits_left_in_littlenum;
+      return_value <<= number_of_bits;
+      bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits;
+      littlenum_pointer--;
+      if (littlenum_pointer >= littlenum_end)
+	return_value |= ((*littlenum_pointer) >> (bits_left_in_littlenum)) &
+	  mask[number_of_bits];
+    }
+  else
+    {
+      bits_left_in_littlenum -= number_of_bits;
+      return_value = mask[number_of_bits] &
+	((*littlenum_pointer) >> bits_left_in_littlenum);
+    }
+  return (return_value);
+}
+
+static void
+make_invalid_floating_point_number (words)
+     LITTLENUM_TYPE *words;
+{
+  *words = 0x8000;		/* Floating Reserved Operand Code */
+}
+
+static int			/* 0 means letter is OK. */
+what_kind_of_float (letter, precisionP, exponent_bitsP)
+     char letter;		/* In: lowercase please. What kind of float? */
+     int *precisionP;		/* Number of 16-bit words in the float. */
+     long int *exponent_bitsP;	/* Number of exponent bits. */
+{
+  int retval;			/* 0: OK. */
+
+  retval = 0;
+  switch (letter)
+    {
+    case 'f':
+      *precisionP = F_PRECISION;
+      *exponent_bitsP = 8;
+      break;
+
+    case 'd':
+      *precisionP = D_PRECISION;
+      *exponent_bitsP = 8;
+      break;
+
+    default:
+      retval = 69;
+      break;
+    }
+  return (retval);
+}
+
+/***********************************************************************\
+*									*
+*	Warning: this returns 16-bit LITTLENUMs, because that is	*
+*	what the VAX thinks in. It is up to the caller to figure	*
+*	out any alignment problems and to conspire for the bytes/word	*
+*	to be emitted in the right order. Bigendians beware!		*
+*									*
+\***********************************************************************/
+
+char *				/* Return pointer past text consumed. */
+atof_tahoe (str, what_kind, words)
+     char *str;			/* Text to convert to binary. */
+     char what_kind;		/* 'd', 'f', 'g', 'h' */
+     LITTLENUM_TYPE *words;	/* Build the binary here. */
+{
+  FLONUM_TYPE f;
+  LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD];
+  /* Extra bits for zeroed low-order bits. */
+  /* The 1st MAX_PRECISION are zeroed, */
+  /* the last contain flonum bits. */
+  char *return_value;
+  int precision;		/* Number of 16-bit words in the format. */
+  long int exponent_bits;
+
+  return_value = str;
+  f.low = bits + MAX_PRECISION;
+  f.high = NULL;
+  f.leader = NULL;
+  f.exponent = NULL;
+  f.sign = '\0';
+
+  if (what_kind_of_float (what_kind, &precision, &exponent_bits))
+    {
+      return_value = NULL;	/* We lost. */
+      make_invalid_floating_point_number (words);
+    }
+  if (return_value)
+    {
+      memset (bits, '\0', sizeof (LITTLENUM_TYPE) * MAX_PRECISION);
+
+      /* Use more LittleNums than seems */
+      /* necessary: the highest flonum may have */
+      /* 15 leading 0 bits, so could be useless. */
+      f.high = f.low + precision - 1 + GUARD;
+
+      if (atof_generic (&return_value, ".", "eE", &f))
+	{
+	  make_invalid_floating_point_number (words);
+	  return_value = NULL;	/* we lost */
+	}
+      else
+	{
+	  if (flonum_gen2tahoe (what_kind, &f, words))
+	    {
+	      return_value = NULL;
+	    }
+	}
+    }
+  return (return_value);
+}
+
+/*
+ * In: a flonum, a Tahoe floating point format.
+ * Out: a Tahoe floating-point bit pattern.
+ */
+
+int				/* 0: OK. */
+flonum_gen2tahoe (format_letter, f, words)
+     char format_letter;	/* One of 'd' 'f'. */
+     FLONUM_TYPE *f;
+     LITTLENUM_TYPE *words;	/* Deliver answer here. */
+{
+  LITTLENUM_TYPE *lp;
+  int precision;
+  long int exponent_bits;
+  int return_value;		/* 0 == OK. */
+
+  return_value = what_kind_of_float (format_letter, &precision, &exponent_bits);
+  if (return_value != 0)
+    {
+      make_invalid_floating_point_number (words);
+    }
+  else
+    {
+      if (f->low > f->leader)
+	{
+	  /* 0.0e0 seen. */
+	  memset (words, '\0', sizeof (LITTLENUM_TYPE) * precision);
+	}
+      else
+	{
+	  long int exponent_1;
+	  long int exponent_2;
+	  long int exponent_3;
+	  long int exponent_4;
+	  int exponent_skippage;
+	  LITTLENUM_TYPE word1;
+
+	  /* JF: Deal with new Nan, +Inf and -Inf codes */
+	  if (f->sign != '-' && f->sign != '+')
+	    {
+	      make_invalid_floating_point_number (words);
+	      return return_value;
+	    }
+	  /*
+	   * All tahoe floating_point formats have:
+	   * Bit 15 is sign bit.
+	   * Bits 14:n are excess-whatever exponent.
+	   * Bits n-1:0 (if any) are most significant bits of fraction.
+	   * Bits 15:0 of the next word are the next most significant bits.
+	   * And so on for each other word.
+	   *
+	   * So we need: number of bits of exponent, number of bits of
+	   * mantissa.
+	   */
+
+	  bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
+	  littlenum_pointer = f->leader;
+	  littlenum_end = f->low;
+	  /* Seek (and forget) 1st significant bit */
+	  for (exponent_skippage = 0;
+	       !next_bits (1);
+	       exponent_skippage++)
+	    {
+	    }
+	  exponent_1 = f->exponent + f->leader + 1 - f->low;
+	  /* Radix LITTLENUM_RADIX, point just higher than f -> leader. */
+	  exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS;
+	  /* Radix 2. */
+	  exponent_3 = exponent_2 - exponent_skippage;
+	  /* Forget leading zeros, forget 1st bit. */
+	  exponent_4 = exponent_3 + (1 << (exponent_bits - 1));
+	  /* Offset exponent. */
+
+	  if (exponent_4 & ~mask[exponent_bits])
+	    {
+	      /*
+	       * Exponent overflow. Lose immediately.
+	       */
+
+	      make_invalid_floating_point_number (words);
+
+	      /*
+	       * We leave return_value alone: admit we read the
+	       * number, but return a floating exception
+	       * because we can't encode the number.
+	       */
+	    }
+	  else
+	    {
+	      lp = words;
+
+	      /* Word 1. Sign, exponent and perhaps high bits. */
+	      /* Assume 2's complement integers. */
+	      word1 = ((exponent_4 & mask[exponent_bits]) << (15 - exponent_bits))
+		| ((f->sign == '+') ? 0 : 0x8000)
+		| next_bits (15 - exponent_bits);
+	      *lp++ = word1;
+
+	      /* The rest of the words are just mantissa bits. */
+	      for (; lp < words + precision; lp++)
+		{
+		  *lp = next_bits (LITTLENUM_NUMBER_OF_BITS);
+		}
+
+	      if (next_bits (1))
+		{
+		  /*
+		   * Since the NEXT bit is a 1, round UP the mantissa.
+		   * The cunning design of these hidden-1 floats permits
+		   * us to let the mantissa overflow into the exponent, and
+		   * it 'does the right thing'. However, we lose if the
+		   * highest-order bit of the lowest-order word flips.
+		   * Is that clear?
+		   */
+
+		  unsigned long int carry;
+
+		  /*
+		    #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2)
+		    Please allow at least 1 more bit in carry than is in a LITTLENUM.
+		    We need that extra bit to hold a carry during a LITTLENUM carry
+		    propagation. Another extra bit (kept 0) will assure us that we
+		    don't get a sticky sign bit after shifting right, and that
+		    permits us to propagate the carry without any masking of bits.
+		    #endif
+		    */
+		  for (carry = 1, lp--;
+		       carry && (lp >= words);
+		       lp--)
+		    {
+		      carry = *lp + carry;
+		      *lp = carry;
+		      carry >>= LITTLENUM_NUMBER_OF_BITS;
+		    }
+
+		  if ((word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1)))
+		    {
+		      make_invalid_floating_point_number (words);
+		      /*
+		       * We leave return_value alone: admit we read the
+		       * number, but return a floating exception
+		       * because we can't encode the number.
+		       */
+		    }
+		}		/* if (we needed to round up) */
+	    }			/* if (exponent overflow) */
+	}			/* if (0.0e0) */
+    }				/* if (float_type was OK) */
+  return (return_value);
+}
+
+/*
+ *		md_atof()
+ *
+ * In:	input_line_pointer -> the 1st character of a floating-point
+ *		number.
+ *	1 letter denoting the type of statement that wants a
+ *		binary floating point number returned.
+ *	Address of where to build floating point literal.
+ *		Assumed to be 'big enough'.
+ *	Address of where to return size of literal (in chars).
+ *
+ * Out:	Input_line_pointer -> of next char after floating number.
+ *	Error message, or "".
+ *	Floating point literal.
+ *	Number of chars we used for the literal.
+ */
+
+char *
+md_atof (what_statement_type, literalP, sizeP)
+     char what_statement_type;
+     char *literalP;
+     int *sizeP;
+{
+  LITTLENUM_TYPE words[MAX_PRECISION];
+  register char kind_of_float;
+  register int number_of_chars;
+  register LITTLENUM_TYPE *littlenum_pointer;
+
+  switch (what_statement_type)
+    {
+    case 'f':			/* .ffloat */
+    case 'd':			/* .dfloat */
+      kind_of_float = what_statement_type;
+      break;
+
+    default:
+      kind_of_float = 0;
+      break;
+    };
+
+  if (kind_of_float)
+    {
+      register LITTLENUM_TYPE *limit;
+
+      input_line_pointer = atof_tahoe (input_line_pointer,
+				       kind_of_float,
+				       words);
+      /*
+       * The atof_tahoe() builds up 16-bit numbers.
+       * Since the assembler may not be running on
+       * a different-endian machine, be very careful about
+       * converting words to chars.
+       */
+      number_of_chars = (kind_of_float == 'f' ? F_PRECISION_CHARS :
+			 (kind_of_float == 'd' ? D_PRECISION_CHARS : 0));
+      know (number_of_chars <= MAX_PRECISION * sizeof (LITTLENUM_TYPE));
+      limit = words + (number_of_chars / sizeof (LITTLENUM_TYPE));
+      for (littlenum_pointer = words;
+	   littlenum_pointer < limit;
+	   littlenum_pointer++)
+	{
+	  md_number_to_chars (literalP, *littlenum_pointer,
+			      sizeof (LITTLENUM_TYPE));
+	  literalP += sizeof (LITTLENUM_TYPE);
+	};
+    }
+  else
+    {
+      number_of_chars = 0;
+    };
+
+  *sizeP = number_of_chars;
+  return (kind_of_float ? "" : "Bad call to md_atof()");
+}				/* md_atof() */
+
+/* atof_tahoe.c */