D38034.diff
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	diff --git a/sys/sys/limits.h b/sys/sys/limits.h
	--- a/sys/sys/limits.h
	+++ b/sys/sys/limits.h
	@@ -90,6 +90,26 @@
	#define QUAD_MIN (__QUAD_MIN) /* min value for a quad_t */
	#endif

	+/*
	+ * Programmatically determine the maximum value of
	+ * an unsigned and signed type, without integer overflow.
	+ *
	+ * After determining the byte-size of the type,
	+ * e.g. 2 for uint16_t, set the left-most bit. (0x8000)
	+ * Set all bits but the highest by subtracting one. (0x7FFF)
	+ * Shift all set bits left by one by way of muliply by 2. (0xFFFE)
	+ * Finally, set the lowest bit by adding one. (0xFFFF)
	+ *
	+ * This is a portable way to programmatically determine
	+ * the maximum value of an unsigned variable of arbitrary size.
	+ */
	+#define UTYPE_MAX(x) \
	+ ((((1ULL << (sizeof((x)) * 8 - 1)) - 1) * 2) + 1)
	+
	+#define TYPE_MAX(x) \
	+ ((((1ULL << (sizeof((x)) * 8 - 2)) - 1) * 2) + 1)
	+
	+
	#if __XSI_VISIBLE \|\| __POSIX_VISIBLE >= 200809
	#define LONG_BIT __LONG_BIT
	#define WORD_BIT __WORD_BIT