gossip: Added short_channel_id_to_uint for uintmap index

Signed-off-by: Christian Decker <decker.christian@gmail.com>

bitcoin/short_channel_id.c

@@ -32,3 +32,9 @@ bool short_channel_id_eq(const struct short_channel_id *a,
 	return a->blocknum == b->blocknum && a->txnum == b->txnum &&
 	       a->outnum == b->outnum;
 }
+
+u64 short_channel_id_to_uint(const struct short_channel_id *scid)
+{
+	return ((u64)scid->blocknum & 0xFFFFFF) << 40 |
+	       ((u64)scid->txnum & 0xFFFFFF) << 16 | (scid->outnum & 0xFFFF);
+}

bitcoin/short_channel_id.h

@@ -25,4 +25,7 @@ bool short_channel_id_eq(const struct short_channel_id *a,
 
 char *short_channel_id_to_str(const tal_t *ctx, const struct short_channel_id *scid);
 
+/* Fast, platform dependent, way to convert from a short_channel_id to u64 */
+u64 short_channel_id_to_uint(const struct short_channel_id *scid);
+
 #endif /* LIGHTNING_BITCOIN_SHORT_CHANNEL_ID_H */