ump: Add a function to provide the packet word length of a UMP type

Add a helper function to return the number of words of a given UMP
packet type.  Used for parsing MIDI Clip File stream, for example.

Signed-off-by: Takashi Iwai <[email protected]>

include/ump_msg.h

@@ -1003,6 +1003,7 @@ static inline uint8_t snd_ump_sysex_msg_length(const uint32_t *ump)
 
 int snd_ump_msg_sysex_expand(const uint32_t *ump, uint8_t *buf, size_t maxlen,
 			     size_t *filled);
+int snd_ump_packet_length(unsigned int type);
 
 #ifdef __cplusplus
 }

src/Versions.in.in

@@ -212,5 +212,6 @@ ALSA_1.2.13 {
     @SYMBOL_PREFIX@snd_ump_endpoint_info_set_*;
     @SYMBOL_PREFIX@snd_ump_block_info_clear;
     @SYMBOL_PREFIX@snd_ump_block_info_set_*;
+    @SYMBOL_PREFIX@snd_ump_packet_length;
 #endif
 } ALSA_1.2.10;

src/rawmidi/ump.c

@@ -1072,3 +1072,20 @@ int snd_ump_msg_sysex_expand(const uint32_t *ump, uint8_t *buf, size_t maxlen,
 		return -EINVAL;
 	}
 }
+
+/**
+ * \brief return the length of a UMP packet type
+ * \param type UMP packet type
+ * \return the length of the given UMP packet type in 32bit words (from 1 to 4),
+ *   or 0 for negative inputs.
+ */
+int snd_ump_packet_length(unsigned int type)
+{
+	static int packet_length[16] = {
+		1, 1, 1, 2, 2, 4, 1, 1, 2, 2, 2, 3, 3, 4, 4, 4
+	};
+
+	if (type > 16)
+		return 0;
+	return packet_length[type];
+}