First implementation - untested, v0.1.0

README.md

@@ -1,2 +1,5 @@
 # crc16
 
+An CRC-16 implementation
+
+Made with this https://www.sunshine2k.de/articles/coding/crc/understanding_crc.html#ch4 tutorial.

crc.go

@@ -0,0 +1,32 @@
+package crc16
+
+var Crc16Table = make([]uint16, 256)
+
+const GeneratorPolynomial = 0x1021
+
+func init() {
+	calculateTable()
+}
+
+func calculateTable() {
+	for dividend := 0; dividend < 256; dividend++ {
+		crc := uint16(dividend << 8)
+		for bit := 0; bit < 8; bit++ {
+			if (crc & 0x8000) != 0 {
+				crc = (crc << 1) ^ GeneratorPolynomial
+			} else {
+				crc <<= 1
+			}
+		}
+		Crc16Table[dividend] = crc
+	}
+}
+
+func Calculate(data []byte) uint16 {
+	crc := uint16(0)
+	for _, b := range data {
+		pos := byte(crc>>8) ^ b
+		crc = (crc << 8) ^ Crc16Table[pos]
+	}
+	return crc
+}

go.mod

@@ -0,0 +1,3 @@
+module git.barfuss.email/jan/crc16
+
+go 1.22.1