add support for reading and writing QUIC's ufloat16

utils/float16_test.go

@@ -0,0 +1,144 @@
+package utils
+
+import (
+	"bytes"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("float16", func() {
+	It("reads", func() {
+		testcases := []struct {
+			expected uint64
+			binary   uint16
+		}{
+			// There are fewer decoding test cases because encoding truncates, and
+			// decoding returns the smallest expansion.
+			// Small numbers represent themselves.
+			{0, 0},
+			{1, 1},
+			{2, 2},
+			{3, 3},
+			{4, 4},
+			{5, 5},
+			{6, 6},
+			{7, 7},
+			{15, 15},
+			{31, 31},
+			{42, 42},
+			{123, 123},
+			{1234, 1234},
+			// Check transition through 2^11.
+			{2046, 2046},
+			{2047, 2047},
+			{2048, 2048},
+			{2049, 2049},
+			// Running out of mantissa at 2^12.
+			{4094, 4094},
+			{4095, 4095},
+			{4096, 4096},
+			{4098, 4097},
+			{4100, 4098},
+			// Check transition through 2^13.
+			{8190, 6143},
+			{8192, 6144},
+			{8196, 6145},
+			// Half-way through the exponents.
+			{0x7FF8000, 0x87FF},
+			{0x8000000, 0x8800},
+			{0xFFF0000, 0x8FFF},
+			{0x10000000, 0x9000},
+			// Transition into the largest exponent.
+			{0x1FFE0000000, 0xF7FF},
+			{0x20000000000, 0xF800},
+			{0x20040000000, 0xF801},
+			// Transition into the max value.
+			{0x3FF80000000, 0xFFFE},
+			{0x3FFC0000000, 0xFFFF},
+		}
+		for _, testcase := range testcases {
+			b := &bytes.Buffer{}
+			WriteUint16(b, testcase.binary)
+			val, err := ReadUfloat16(b)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(val).To(Equal(testcase.expected))
+		}
+	})
+
+	It("writes", func() {
+		testcases := []struct {
+			decoded uint64
+			encoded uint16
+		}{
+			// Small numbers represent themselves.
+			{0, 0},
+			{1, 1},
+			{2, 2},
+			{3, 3},
+			{4, 4},
+			{5, 5},
+			{6, 6},
+			{7, 7},
+			{15, 15},
+			{31, 31},
+			{42, 42},
+			{123, 123},
+			{1234, 1234},
+			// Check transition through 2^11.
+			{2046, 2046},
+			{2047, 2047},
+			{2048, 2048},
+			{2049, 2049},
+			// Running out of mantissa at 2^12.
+			{4094, 4094},
+			{4095, 4095},
+			{4096, 4096},
+			{4097, 4096},
+			{4098, 4097},
+			{4099, 4097},
+			{4100, 4098},
+			{4101, 4098},
+			// Check transition through 2^13.
+			{8190, 6143},
+			{8191, 6143},
+			{8192, 6144},
+			{8193, 6144},
+			{8194, 6144},
+			{8195, 6144},
+			{8196, 6145},
+			{8197, 6145},
+			// Half-way through the exponents.
+			{0x7FF8000, 0x87FF},
+			{0x7FFFFFF, 0x87FF},
+			{0x8000000, 0x8800},
+			{0xFFF0000, 0x8FFF},
+			{0xFFFFFFF, 0x8FFF},
+			{0x10000000, 0x9000},
+			// Transition into the largest exponent.
+			{0x1FFFFFFFFFE, 0xF7FF},
+			{0x1FFFFFFFFFF, 0xF7FF},
+			{0x20000000000, 0xF800},
+			{0x20000000001, 0xF800},
+			{0x2003FFFFFFE, 0xF800},
+			{0x2003FFFFFFF, 0xF800},
+			{0x20040000000, 0xF801},
+			{0x20040000001, 0xF801},
+			// Transition into the max value and clamping.
+			{0x3FF80000000, 0xFFFE},
+			{0x3FFBFFFFFFF, 0xFFFE},
+			{0x3FFC0000000, 0xFFFF},
+			{0x3FFC0000001, 0xFFFF},
+			{0x3FFFFFFFFFF, 0xFFFF},
+			{0x40000000000, 0xFFFF},
+			{0xFFFFFFFFFFFFFFFF, 0xFFFF},
+		}
+		for _, testcase := range testcases {
+			b := &bytes.Buffer{}
+			WriteUfloat16(b, testcase.decoded)
+			val, err := ReadUint16(b)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(val).To(Equal(testcase.encoded))
+		}
+	})
+})