base: print() functions for floating point types

Fixes #2055

repos/base/include/base/output.h

@@ -120,6 +120,16 @@ namespace Genode {
 		print(output, (int)value);
 	}
 
+	/**
+	 * Print single-precision float
+	 */
+	void print(Output &output, float);
+
+	/**
+	 * Print double-precision float
+	 */
+	void print(Output &output, double);
+
 	/**
 	 * Helper for the hexadecimal output of integer values
 	 *

repos/base/src/include/base/internal/output.h

@@ -108,6 +108,39 @@ static inline void out_unsigned(T value, unsigned base, int pad,
 }
 
 
+/**
+ * Output floating point value
+ */
+template <typename T, typename OUT_CHAR_FN>
+static inline void out_float(T value, unsigned base, unsigned length, OUT_CHAR_FN const &out_char)
+{
+	/* set flag if value is negative */
+	int neg = value < 0 ? 1 : 0;
+
+	/* get absolute value */
+	value = value < 0 ? -value : value;
+
+	uint64_t integer = (uint64_t)value;
+
+	if (neg)
+		out_char('-');
+
+	out_unsigned(integer, base, 0, out_char);
+	out_char('.');
+
+	if (length) {
+		do {
+			value -= integer;
+			value = value*base;
+
+			integer = (int64_t)value;
+			out_char(ascii(integer));
+
+			length--;
+		} while (length && (value > 0.0));
+	}
+}
+
 namespace Genode { template <size_t, typename> class Buffered_output; }
 
 

repos/base/src/lib/base/output.cc

@@ -75,6 +75,15 @@ void Genode::print(Output &output, long long value)
 	out_signed<long long>(value, 10, [&] (char c) { output.out_char(c); });
 }
 
+void Genode::print(Output &output, float value)
+{
+	out_float<float>(value, 10, 3, [&] (char c) { output.out_char(c); });
+}
+
+void Genode::print(Output &output, double value)
+{
+	out_float<double>(value, 10, 6, [&] (char c) { output.out_char(c); });
+}
 
 void Genode::print(Output &output, Hex const &value)
 {