Initial revision

lib/float/extend.c

@@ -0,0 +1,111 @@
+/*
+  (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
+  See the copyright notice in the ACK home directory, in the file "Copyright".
+*/
+
+/* $Header$ */
+
+/*
+	CONVERTS FLOATING POINT TO EXTENDED FORMAT
+
+	Two sizes of FLOATING Point are known:
+		SINGLE and DOUBLE
+*/
+/********************************************************/
+/*
+	It is not required to normalize in extended
+	format, but it has been chosen to do so.
+	Extended Format is as follows (at exit):
+
+->sign	S000 0000 | 0000 0000		<SIGN>
+->exp	0EEE EEEE | EEEE EEEE		<EXPONENT>
+->m1	LFFF FFFF | FFFF FFFF		<L.Fraction>
+	FFFF FFFF | FFFF FFFF		<Fraction>
+->m2	FFFF FFFF | FFFF FFFF		<Fraction>
+	FFFF F000 | 0000 0000		<Fraction>
+*/
+/********************************************************/
+
+#include "FP_bias.h"
+#include "FP_shift.h"
+#include "FP_types.h"
+#include "get_put.h"
+/********************************************************/
+
+void
+extend(from,to,size)
+unsigned long	*from;
+EXTEND	*to;
+int	size;
+{
+	register char *cpt1;
+	unsigned long	tmp;
+	int	leadbit = 0;
+
+	cpt1 = (char *) from;
+
+#if FL_MSL_AT_LOW_ADDRESS
+#if FL_MSW_AT_LOW_ADDRESS
+	to->exp = uget2(cpt1);
+#else
+	to->exp = uget2(cpt1+2);
+#endif
+#else
+#if FL_MSW_AT_LOW_ADDRESS
+	to->exp = uget2(cpt1+(size == sizeof(DOUBLE) ? 4 : 0));
+#else
+	to->exp = uget2(cpt1+(size == sizeof(DOUBLE) ? 6 : 2));
+#endif
+#endif
+	to->sign = (to->exp & 0x8000);	/* set sign bit */
+	to->exp ^= to->sign;
+	if (size == sizeof(DOUBLE))
+		to->exp >>= DBL_EXPSHIFT;
+	else
+		to->exp >>= SGL_EXPSHIFT;
+	if (to->exp > 0)
+		leadbit++;	/* will set Lead bit later	*/
+	else to->exp++;
+
+	if (size == sizeof(DOUBLE))	{
+#if FL_MSL_AT_LOW_ADDRESS
+		to->m1 = get4(cpt1);
+		cpt1 += 4;
+		tmp = get4(cpt1);
+#else
+		tmp = get4(cpt1);
+		cpt1 += 4;
+		to->m1 = get4(cpt1);
+#endif
+		if (to->exp == 1 && to->m1 == 0 && tmp == 0) {
+			to->exp = 0;
+			to->sign = 0;
+			to->m1 = 0;
+			to->m2 = 0;
+			return;
+		}
+		to->m1 <<= DBL_M1LEFT;		/* shift	*/
+		to->exp -= DBL_BIAS;		/* remove bias	*/
+		to->m1 |= (tmp>>DBL_RPACK);	/* plus 10 == 32	*/
+		to->m2 = (tmp<<DBL_LPACK);	/* plus 22 == 32	*/
+	}
+	else	{	/* size == sizeof(SINGLE)		*/
+		to->m1 = get4(cpt1);
+		to->m1  <<= SGL_M1LEFT;	/* shift	*/
+		if (to->exp == 1 && to->m1 == 0) {
+			to->exp = 0;
+			to->sign = 0;
+			to->m1 = 0;
+			to->m2 = 0;
+			return;
+		}
+		to->exp -= SGL_BIAS;		/* remove bias	*/
+		to->m2 = 0L;
+	}
+
+	to->m1 |= NORMBIT;				/* set bit L	*/
+	if (leadbit == 0) {		/* set or clear Leading Bit	*/
+		to->m1 &= ~NORMBIT;			/* clear bit L	*/
+		nrm_ext(to);				/* and normalize */
+	}
+}