Implement protocol versioning (except PGM)

Implements SP protocol versioning, legacy protocol support, and the
following pattern protocol versions:

PAIR:     v2
PUBSUB:   v1 (legacy), v3
REQREP:   v1
PIPELINE: v2
SURVEY:   v1

Engine support is only for stream_engine_t at this stage.

Signed-off-by: Martin Lucina <martin@lucina.net>

1 files changed, 41 insertions, 2 deletions

diff --git a/src/wire.hpp b/src/wire.hpp
index f840fce..e751818 100644
--- a/src/wire.hpp
+++ b/src/wire.hpp
@@ -24,11 +24,50 @@
 #include "stdint.hpp"
 
 //  Protocol-related constants.
-#define XS_CMD_SUBSCRIBE 1
-#define XS_CMD_UNSUBSCRIBE 2
+
+//  Protocol header.
+#define SP_HEADER_LENGTH 8
+
+//  Patterns.
+#define SP_PAIR 1
+#define SP_PUBSUB 2
+#define SP_REQREP 3
+#define SP_PIPELINE 4
+#define SP_SURVEY 5
+
+//  Roles.
+#define SP_PAIR_PAIR 1
+#define SP_PUBSUB_PUB 1
+#define SP_PUBSUB_SUB 2
+#define SP_REQREP_REQ 1
+#define SP_REQREP_REP 2
+#define SP_PIPELINE_PUSH 1
+#define SP_PIPELINE_PULL 2
+#define SP_SURVEY_SURVEYOR 1
+#define SP_SURVEY_RESPONDENT 2
+
+//  PUBSUB pattern commands.
+#define SP_PUBSUB_CMD_SUBSCRIBE 1
+#define SP_PUBSUB_CMD_UNSUBSCRIBE 2
 
 namespace xs
 {
+    //  Protocol header type.
+    typedef unsigned char sp_header_t [SP_HEADER_LENGTH];
+
+    //  Get the SP protocol header for the specified pattern, version and role.
+    inline void sp_get_header (sp_header_t header_, int pattern_, int version_,
+        int role_)
+    {
+        header_ [0] = 0;
+        header_ [1] = 0;
+        header_ [2] = 'S';
+        header_ [3] = 'P';
+        header_ [4] = pattern_ & 0xff;
+        header_ [5] = version_ & 0xff;
+        header_ [6] = role_ & 0xff;
+        header_ [7] = 0;
+    }
 
     //  Helper functions to convert different integer types to/from network
     //  byte order.