From c67750ad181372321dbc38d8069297050048cd1f Mon Sep 17 00:00:00 2001
From: Thorsten von Eicken <tve@rightscale.com>
Date: Tue, 27 Sep 2016 23:33:57 -0700
Subject: [PATCH] add support to reset slip communication

---
 cmd/cmd.c      |  8 +++++---
 cmd/cmd.h      |  8 +++++++-
 cmd/handlers.c | 10 +++++++++-
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/cmd/cmd.c b/cmd/cmd.c
index 705ee8a..4a8dc64 100644
--- a/cmd/cmd.c
+++ b/cmd/cmd.c
@@ -13,8 +13,6 @@
 #define DBG(format, ...) do { } while(0)
 #endif
 
-extern const CmdList commands[];
-
 //===== ESP -> Serial responses
 
 static void ICACHE_FLASH_ATTR
@@ -128,7 +126,11 @@ cmdParsePacket(uint8_t *buf, short len) {
   }
 #endif
 
-  if (data_ptr <= data_limit) {
+  if (!cmdInSync && packet->cmd != CMD_SYNC) {
+    // we have not received a sync, perhaps we reset? Tell MCU to do a sync
+    cmdResponseStart(CMD_SYNC, 0, 0);
+    cmdResponseEnd();
+  } else if (data_ptr <= data_limit) {
     cmdExec(commands, packet);
   } else {
     DBG("cmdParsePacket: packet length overrun, parsing arg %d\n", packet->argc);
diff --git a/cmd/cmd.h b/cmd/cmd.h
index be1e684..d1a8b19 100644
--- a/cmd/cmd.h
+++ b/cmd/cmd.h
@@ -6,6 +6,9 @@
 #define CMD_H
 #include <esp8266.h>
 
+// keep track of whether we received a sync command from uC
+extern bool cmdInSync;
+
 // Standard SLIP escape chars from RFC
 #define SLIP_END      0300    // indicates end of packet
 #define SLIP_ESC      0333    // indicates byte stuffing
@@ -48,7 +51,7 @@ typedef enum {
   CMD_REST_SETUP = 20,
   CMD_REST_REQUEST,
   CMD_REST_SETHEADER,
-  
+
   CMD_WEB_DATA = 30,  // MCU pushes data using this command
   CMD_WEB_REQ_CB,     // esp-link WEB callback
 } CmdName;
@@ -61,6 +64,9 @@ typedef struct {
   cmdfunc_t sc_function; // pointer to function
 } CmdList;
 
+// command dispatch table
+extern const CmdList commands[];
+
 #define CMD_CBNLEN 16
 typedef struct {
   char name[CMD_CBNLEN];
diff --git a/cmd/handlers.c b/cmd/handlers.c
index af328e7..1b45e1f 100644
--- a/cmd/handlers.c
+++ b/cmd/handlers.c
@@ -5,6 +5,7 @@
 #include "esp8266.h"
 #include "sntp.h"
 #include "cmd.h"
+#include "uart.h"
 #include <cgiwifi.h>
 #ifdef MQTT
 #include <mqtt_cmd.h>
@@ -28,7 +29,10 @@ static void cmdAddCallback(CmdPacket *cmd);
 
 // keep track of last status sent to uC so we can notify it when it changes
 static uint8_t lastWifiStatus = wifiIsDisconnected;
+// keep track of whether we have registered our cb handler with the wifi subsystem
 static bool wifiCbAdded = false;
+// keep track of whether we received a sync command from uC
+bool cmdInSync = false;
 
 // Command dispatch table for serial -> ESP commands
 const CmdList commands[] = {
@@ -53,7 +57,7 @@ const CmdList commands[] = {
 
 //===== List of registered callbacks (to uC)
 
-// WifiCb plus 10 for sensors
+// WifiCb plus 10 for other stuff
 #define MAX_CALLBACKS 12
 CmdCallback callbacks[MAX_CALLBACKS]; // cleared in cmdSync
 
@@ -118,6 +122,7 @@ cmdNull(CmdPacket *cmd) {
 static void ICACHE_FLASH_ATTR
 cmdSync(CmdPacket *cmd) {
   CmdRequest req;
+  uart0_write_char(SLIP_END); // prefix with a SLIP END to ensure we get a clean start
   cmdRequest(&req, cmd);
   if(cmd->argc != 0 || cmd->value == 0) {
     cmdResponseStart(CMD_RESP_V, 0, 0);
@@ -128,6 +133,8 @@ cmdSync(CmdPacket *cmd) {
   // clear callbacks table
   os_memset(callbacks, 0, sizeof(callbacks));
 
+  // TODO: call other protocols back to tell them to reset
+
   // register our callback with wifi subsystem
   if (!wifiCbAdded) {
     wifiAddStateChangeCb(cmdWifiCb);
@@ -137,6 +144,7 @@ cmdSync(CmdPacket *cmd) {
   // send OK response
   cmdResponseStart(CMD_RESP_V, cmd->value, 0);
   cmdResponseEnd();
+  cmdInSync = true;
 
   // save the MCU's callback and trigger an initial callback
   cmdAddCb("wifiCb", cmd->value);