Handle half NaN as per standard

PJK · Apr 26, 2015 · bceb5d8 · bceb5d8
1 parent 4b03a98
commit bceb5d8
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Showing 2 changed files with 12 additions and 2 deletions.
diff --git a/src/cbor_encoders.c b/src/cbor_encoders.c
@@ -220,7 +220,10 @@ size_t cbor_encode_half(float value, unsigned char * buffer, size_t buffer_size)
 	uint8_t exp = (val & 0x7F800000) >> 23; /* 0b0111_1111_1000_0000_0000_0000_0000_0000 */
 	uint32_t mant = val & 0x7FFFFF; /* 0b0000_0000_0111_1111_1111_1111_1111_1111 */
 	if (exp == 0xFF) { /* Infinity or NaNs */
-		res = (val & 0x80000000) >> 16 | 0x7C00 | (mant ? 1 : 0);
+		if (value != value)
+			res = (uint16_t)0x00e700; /* Not IEEE semantics - required by CBOR [s. 3.9] */
+		else
+			res = (val & 0x80000000) >> 16 | 0x7C00 | (mant ? 1 : 0) << 15;
 	} else if (exp == 0x00) { /* Zeroes or subnorms */
 		res = (val & 0x80000000) >> 16 | (uint16_t)(mant >> 13);
 	} else { /* Normal numbers */

diff --git a/test/type_7_encoders_test.c b/test/type_7_encoders_test.c
@@ -45,6 +45,12 @@ static void test_half(void **state) {
 	assert_memory_equal(buffer, ((unsigned char[]){ 0xF9, 0x7C, 0x00 }), 3);
 }
 
+static void test_half_special(void **state)
+{
+	assert_int_equal(3, cbor_encode_half(NAN, buffer, 512));
+	assert_memory_equal(buffer, ((unsigned char[]){ 0xF9, 0xE7, 0x00 }), 3);
+}
+
 static void test_float(void **state) {
 	assert_int_equal(5, cbor_encode_float(3.4028234663852886e+38, buffer, 512));
 	assert_memory_equal(buffer, ((unsigned char[]){ 0xFA, 0x7F, 0x7F, 0xFF, 0xFF }), 5);
@@ -63,7 +69,8 @@ int main(void) {
 		unit_test(test_break),
 		unit_test(test_half),
 		unit_test(test_float),
-		unit_test(test_double)
+		unit_test(test_double),
+		unit_test(test_half_special)
 	};
 	return run_tests(tests);
 }