Calculate friend codes for other games

common/friend_code.go

@@ -4,8 +4,70 @@ import (
 	"crypto/md5"
 	"encoding/binary"
 	"fmt"
+	"strings"
 )
 
+const (
+	fcCRC8 = iota
+	fcMD5  = iota
+)
+
+var crc8Table = func() [256]byte {
+	var table [256]byte
+	poly := byte(0x07)
+
+	for i := 0; i < 256; i++ {
+		crc := byte(i)
+
+		for j := 0; j < 8; j++ {
+			if crc&0x80 != 0 {
+				crc = (crc << 1) ^ poly
+			} else {
+				crc <<= 1
+			}
+		}
+
+		table[i] = crc
+	}
+
+	return table
+}()
+
+func crc8(data []byte) byte {
+	crc := byte(0)
+
+	for _, b := range data {
+		crc = crc8Table[crc^b]
+	}
+
+	return crc
+}
+
+func getCRCType(gameId string) (crcType byte, reverse bool) {
+	reverse = false
+
+	if strings.HasPrefix(gameId, "RSB") {
+		crcType = fcCRC8
+		return
+	}
+
+	if strings.HasPrefix(gameId, "HDM") || strings.HasPrefix(gameId, "WDM") {
+		crcType = fcCRC8
+		reverse = true
+		return
+	}
+
+	switch gameId[0] {
+	case 'R', 'S', 'H', 'W', 'X', 'Y':
+		crcType = fcMD5
+
+	default:
+		crcType = fcCRC8
+	}
+
+	return
+}
+
 func CalcFriendCode(pid uint32, gameId string) uint64 {
 	if pid == 0 {
 		return 0
@@ -18,15 +80,29 @@ func CalcFriendCode(pid uint32, gameId string) uint64 {
 	buffer[6] = gameId[1]
 	buffer[7] = gameId[0]
 
+	crc, _ := getCRCType(gameId)
+
+	if crc == fcCRC8 {
+		return uint64(pid) | (uint64(crc8(buffer)&0x7f) << 32)
+	}
+
 	digest := md5.Sum(buffer)
 	return uint64(pid) | (uint64(digest[0]&0xfe) << 31)
 }
 
 func CalcFriendCodeString(pid uint32, gameId string) string {
-	return GetRawFriendCodeString(CalcFriendCode(pid, gameId))
+	_, reverse := getCRCType(gameId)
+
+	return GetRawFriendCodeString(CalcFriendCode(pid, gameId), reverse)
 }
 
-func GetRawFriendCodeString(fc uint64) string {
-	s := fmt.Sprintf("%012d", fc)
+func GetRawFriendCodeString(fc uint64, reverse bool) string {
+	s := fmt.Sprintf("%012d", max(min(fc, 999999999999), 0))
+
+	if reverse {
+		// Reverse the digit order
+		s = s[11:12] + s[10:11] + s[9:10] + s[8:9] + s[7:8] + s[6:7] + s[5:6] + s[4:5] + s[3:4] + s[2:3] + s[1:2] + s[0:1]
+	}
+
 	return s[len(s)-12:len(s)-8] + "-" + s[len(s)-8:len(s)-4] + "-" + s[len(s)-4:]
 }