minimal plan9port to cross-build Jehanne

lib/lib9/fmt/nan64.c

@@ -0,0 +1,78 @@
+/* Copyright (c) 2002-2006 Lucent Technologies; see LICENSE */
+
+/*
+ * 64-bit IEEE not-a-number routines.
+ * This is big/little-endian portable assuming that
+ * the 64-bit doubles and 64-bit integers have the
+ * same byte ordering.
+ */
+
+#include "plan9.h"
+#include <assert.h>
+#include "fmt.h"
+#include "fmtdef.h"
+
+static uvlong uvnan    = ((uvlong)0x7FF00000<<32)|0x00000001;
+static uvlong uvinf    = ((uvlong)0x7FF00000<<32)|0x00000000;
+static uvlong uvneginf = ((uvlong)0xFFF00000<<32)|0x00000000;
+
+/* gcc sees through the obvious casts. */
+static uvlong
+d2u(double d)
+{
+	union {
+		uvlong v;
+		double d;
+	} u;
+	assert(sizeof(u.d) == sizeof(u.v));
+	u.d = d;
+	return u.v;
+}
+
+static double
+u2d(uvlong v)
+{
+	union {
+		uvlong v;
+		double d;
+	} u;
+	assert(sizeof(u.d) == sizeof(u.v));
+	u.v = v;
+	return u.d;
+}
+
+double
+__NaN(void)
+{
+	return u2d(uvnan);
+}
+
+int
+__isNaN(double d)
+{
+	uvlong x;
+
+	x = d2u(d);
+	/* IEEE 754: exponent bits 0x7FF and non-zero mantissa */
+	return (x&uvinf) == uvinf && (x&~uvneginf) != 0;
+}
+
+double
+__Inf(int sign)
+{
+	return u2d(sign < 0 ? uvneginf : uvinf);
+}
+
+int
+__isInf(double d, int sign)
+{
+	uvlong x;
+
+	x = d2u(d);
+	if(sign == 0)
+		return x==uvinf || x==uvneginf;
+	else if(sign > 0)
+		return x==uvinf;
+	else
+		return x==uvneginf;
+}