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CPM OPERATING SYSTEMS/CPM 68K/1.0X SOURCES/v101/c/libf/ffptof.c

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+/*
+	Copyright 1982
+	Alcyon Corporation
+	8716 Production Ave.
+	San Diego, Ca.  92121
+*/
+
+/*char *version "@(#) _ffptof - Feb 1, 1983"; */
+
+/*
+ *	FFP Floating Point Representation to Internal Representation :
+ *		FFP Standard Single Precision Representation Floating Point
+ *
+ *	float
+ *	ffptof(lf)
+ *	long lf;
+ *
+ *	Largest positive number is 3.4 * 10^18 and the smallest positive
+ *	number is 1.2 * 10^-20.
+ *	Rely's on the fact that a long and a float are both 32 bits.
+ */
+
+float
+ffptof(lf)
+long lf;
+{
+	register int exp, count, fsign;
+	float f;
+
+	if (lf == 0L)
+		return(0.0);
+	fsign = (lf & 0x80);
+	exp = (lf & 0x7f) - 0x40;
+	lf = (lf>>8) & 0xffffff;	/* 24 bits of fraction */
+	f = lf;
+	f = f / 16777216.0;	/* 2 ^ 24 */
+	while (exp < 0) {	/* negative exp : 2^-? */
+		f = f / 2.0;
+		exp++;
+	}
+	while (exp > 0) {	/* positive exp : 2^+? */
+		f = f * 2.0;
+		exp--;
+	}
+	if (fsign)
+		f = -f;
+	return(f);
+}