diff --git a/src/main/common/crc.c b/src/main/common/crc.c
index 1ccbd78e5e..afd77b79d1 100644
--- a/src/main/common/crc.c
+++ b/src/main/common/crc.c
@@ -77,3 +77,25 @@ void crc8_dvb_s2_sbuf_append(sbuf_t *dst, uint8_t *start)
     }
     sbufWriteU8(dst, crc);
 }
+
+uint8_t crc8_xor_update(uint8_t crc, const void *data, uint32_t length)
+{
+    const uint8_t *p = (const uint8_t *)data;
+    const uint8_t *pend = p + length;
+
+    for (; p != pend; p++) {
+        crc ^= *p;
+    }
+    return crc;
+}
+
+void crc8_xor_sbuf_append(sbuf_t *dst, uint8_t *start)
+{
+    uint8_t crc = 0;
+    const uint8_t *end = dst->ptr;
+    for (uint8_t *ptr = start; ptr < end; ++ptr) {
+        crc ^= *ptr;
+    }
+    sbufWriteU8(dst, crc);
+}
+
diff --git a/src/main/common/crc.h b/src/main/common/crc.h
index 8e8fbf5557..8aebc3c415 100644
--- a/src/main/common/crc.h
+++ b/src/main/common/crc.h
@@ -17,9 +17,12 @@
 
 #pragma once
 
+struct sbuf_s;
+
 uint16_t crc16_ccitt(uint16_t crc, unsigned char a);
 uint16_t crc16_ccitt_update(uint16_t crc, const void *data, uint32_t length);
 uint8_t crc8_dvb_s2(uint8_t crc, unsigned char a);
 uint8_t crc8_dvb_s2_update(uint8_t crc, const void *data, uint32_t length);
-struct sbuf_s;
 void crc8_dvb_s2_sbuf_append(struct sbuf_s *dst, uint8_t *start);
+uint8_t crc8_xor_update(uint8_t crc, const void *data, uint32_t length);
+void crc8_xor_sbuf_append(struct sbuf_s *dst, uint8_t *start);
diff --git a/src/main/common/streambuf.c b/src/main/common/streambuf.c
index 976439ae81..ad7db189d3 100644
--- a/src/main/common/streambuf.c
+++ b/src/main/common/streambuf.c
@@ -61,6 +61,12 @@ void sbufWriteU32BigEndian(sbuf_t *dst, uint32_t val)
 }
 
 
+void sbufFill(sbuf_t *dst, uint8_t data, int len)
+{
+    memset(dst->ptr, data, len);
+    dst->ptr += len;
+}
+
 void sbufWriteData(sbuf_t *dst, const void *data, int len)
 {
     memcpy(dst->ptr, data, len);
diff --git a/src/main/common/streambuf.h b/src/main/common/streambuf.h
index 790423350e..21f5822fb6 100644
--- a/src/main/common/streambuf.h
+++ b/src/main/common/streambuf.h
@@ -20,19 +20,20 @@
 #include <stdint.h>
 
 // simple buffer-based serializer/deserializer without implicit size check
-// little-endian encoding implemneted now
 
 typedef struct sbuf_s {
-    uint8_t *ptr;          // data pointer must be first (sbuff_t* is equivalent to uint8_t **)
+    uint8_t *ptr;          // data pointer must be first (sbuf_t* is equivalent to uint8_t **)
     uint8_t *end;
 } sbuf_t;
 
 sbuf_t *sbufInit(sbuf_t *sbuf, uint8_t *ptr, uint8_t *end);
+
 void sbufWriteU8(sbuf_t *dst, uint8_t val);
 void sbufWriteU16(sbuf_t *dst, uint16_t val);
 void sbufWriteU32(sbuf_t *dst, uint32_t val);
 void sbufWriteU16BigEndian(sbuf_t *dst, uint16_t val);
 void sbufWriteU32BigEndian(sbuf_t *dst, uint32_t val);
+void sbufFill(sbuf_t *dst, uint8_t data, int len);
 void sbufWriteData(sbuf_t *dst, const void *data, int len);
 void sbufWriteString(sbuf_t *dst, const char *string);
 void sbufWriteStringWithZeroTerminator(sbuf_t *dst, const char *string);