+#define GMC_BUFSIZE 266
+
+/** Message ID bits 4, 5 */
+#define MSGID_MASK 0x30 /**< Mask to get message ID bits */
+#define MSGID_INF 0x00 /**< Start of message with device info */
+#define MSGID_D10 0x10 /**< Start of data message, non-displayed intermediate */
+#define MSGID_DTA 0x20 /**< Start of data message, displayed, averaged */
+#define MSGID_DATA 0x30 /**< Data byte in message */
+
+#define MSGC_MASK 0x0f /**< Mask to get message byte contents */
+
+#define MSGSRC_MASK 0xc0 /**< Mask to get bits related to message source */
+
+#define bc(x) (x & MSGC_MASK) /**< Get contents from a byte */
+
+#define MASK_6BITS 0x3f /**< Mask lower six bits. */
+
+/** Internal multimeter model codes. In opposite to the multimeter models from
+ * protocol (see decode_model()), these codes allow working with ranges.
+ */
+enum model {
+ SR_METRAHIT_NONE = 0, /**< Value for uninitialized variable */
+ SR_METRAHIT_12S = 12,
+ SR_METRAHIT_13S14A = 13,
+ SR_METRAHIT_14S = 14,
+ SR_METRAHIT_15S = 15,
+ SR_METRAHIT_16S = 16,
+ SR_METRAHIT_16I = 17,
+ SR_METRAHIT_16X = SR_METRAHIT_16I, /**< All Metrahit 16 */
+ /* A Metrahit 17 exists, but seems not to have an IR interface. */
+ SR_METRAHIT_18S = 18,
+ SR_METRAHIT_2X = 20, /**< For model type comparisons */
+ SR_METRAHIT_22SM = 22,
+ SR_METRAHIT_23S = 23,
+ SR_METRAHIT_24S = 24,
+ SR_METRAHIT_25SM = 25,
+ SR_METRAHIT_26S = 26,
+ SR_METRAHIT_28S = 28,
+ SR_METRAHIT_29S = 29,
+};
+
+/** Convert GMC model code in send mode to sigrok-internal one. */
+SR_PRIV int sr_gmc_decode_model_sm(guchar mcode);
+
+/** Convert GMC model code in bidirectional mode to sigrok-internal one.
+ \param[in] mcode Model code.
+
+ \return Model code
+*/
+SR_PRIV int sr_gmc_decode_model_bidi(guchar mcode);
+
+/** Create 14-bytes (42 byte) message used in bidirectional mode.
+ * \param[in] addr Target address. 0..15, 0=Broadcast.
+ * \param[in] func Function code.
+ * \param[in] params Further parameters, &char[9]. Unused bytes must be 0.
+ * \param[out] buf &guchar[42] Output buffer (3*14).
+ *
+ */
+void create_msg_14(guchar addr, guchar func, guchar* params, guchar* buf);
+
+/** Get model string from sigrok-internal model code.
+ */
+SR_PRIV const char* sr_gmc_model_str(enum model mcode);
+