Index: ossp-pkg/sio/sio.pod
RCS File: /v/ossp/cvs/ossp-pkg/sio/sio.pod,v
rcsdiff -q -kk '-r1.2' '-r1.3' -u '/v/ossp/cvs/ossp-pkg/sio/sio.pod,v' 2>/dev/null
--- sio.pod	2002/11/08 10:36:35	1.2
+++ sio.pod	2002/11/08 11:03:13	1.3
@@ -405,7 +405,6 @@
      char *c;
  } private_t;
 
- static
  sio_rc_t XXX_init(sio_t *sio, void **up) {
 
      private_t *my;
@@ -427,7 +426,6 @@
 B<sio_create_stage> and a corresponding cleanup function is called
 when the stage is detroyed with B<sio_destroy_stage>.
 
- static
  sio_rc_t XXX_cleanup(sio_t *sio, void *u)
  {
      private_t *my = (private_t *)u;
@@ -444,7 +442,6 @@
 parameters are passed through B<sio_configure_stage> to the
 configure function of the module.
 
- static
  sio_rc_t XXX_configure(sio_t *sio, void *u, void *o, void *v)
  {
      private_t *my = (private_t *)u;
@@ -538,6 +535,86 @@
 assembly line and B<sio_output> schedules all stages attached
 to the output assembly line.
 
+A full-duplex protocol however needs to mix input and output
+operations. This can be done by telling the scheduler to
+cross sides with the result code SIO_XSTREAM and by maintaining
+a state machine that directs the scheduler back to the
+originating track.
+
+Example:
+
+ sio_rc_t XXX_openr(sio_t *sio, al_t *al, void *u)
+ {
+     private_t *my = (private_t *)u;
+     ... 
+     /* cache reference to input assembly line */
+     my->al_in = al;
+     my->state = INIT;
+     ...
+ }
+ sio_rc_t XXX_openw(sio_t *sio, al_t *al, void *u)
+ {
+     private_t *my = (private_t *)u;
+     ... 
+     /* cache reference to output assembly line */
+     my->al_out = al;
+     my->state = INIT;
+     ...
+ }
+ sio_rc_t XXX_input(sio_t *sio, al_t *al, void *u)
+ {
+     return XXX_protocol(sio, (private_t *)u, 0);
+ }
+ sio_rc_t XXX_output(sio_t *sio, al_t *al, void *u)
+ {
+     return XXX_protocol(sio, (private_t *)u, 1);
+ }
+
+
+ sio_rc_t XXX_protocol(sio_t *sio, private_t *my, int isoutput)
+ {
+     switch (my->state) {
+     case INIT:
+        my->isoutput = isoutput;
+        my->state    = NEXT;
+        ...
+        /* protocol needs global assembly lines,
+         * we need to put aside any data */
+        XXX_preserve_al(my);
+
+        /* protocol starts with output */
+        if (isoutput) {
+
+            return SIO_LOOP;    /* next state on this side */
+        } else
+            return SIO_XSTREAM; /* next state on other side */
+
+     case NEXT:
+     ....
+     case INPUT:
+        al_append_bytes(my->al_in, ...);
+     ...
+     case OUTPUT:
+        al_append_bytes(my->al_out, ...);
+     ...
+     case LAST:
+        ...
+        my->state = DONE;
+
+        /* restore global asembly lines */
+        XXX_restore_output(my);
+
+        if (isoutput != my->isoutput)
+            return SIO_XSTREAM;
+        else
+            return SIO_LOOP;
+
+     case DONE:
+     ...
+     }
+     ...
+ }
+
 
 =back