Experimental: add new WiFi (pseudo) modes: WIFI_SHUTDOWN & WIFI_RESUME (#6356)

* add new WiFimodes: WIFI_SHUTDOWN & WIFI_RESUME with example
* restore WiFi.onWiFiModeChange()

Author: d-a-v

cores/esp8266/core_esp8266_eboot_command.cpp

@@ -21,36 +21,15 @@
 
 #include <stddef.h>
 #include <stdbool.h>
+#include "coredecls.h"
 #include "eboot_command.h"
 
-extern "C" {
 
-static uint32_t crc_update(uint32_t crc, const uint8_t *data, size_t length)
-{
-    uint32_t i;
-    bool bit;
-    uint8_t c;
-    
-    while (length--) {
-        c = *data++;
-        for (i = 0x80; i > 0; i >>= 1) {
-            bit = crc & 0x80000000;
-            if (c & i) {
-                bit = !bit;
-            }
-            crc <<= 1;
-            if (bit) {
-                crc ^= 0x04c11db7;
-            }
-        }
-    }
-    return crc;
-}
+extern "C" {
 
 static uint32_t eboot_command_calculate_crc32(const struct eboot_command* cmd)
 {
-    return crc_update(0xffffffff, (const uint8_t*) cmd, 
-                      offsetof(struct eboot_command, crc32));
+    return crc32((const uint8_t*) cmd, offsetof(struct eboot_command, crc32));
 }
 
 int eboot_command_read(struct eboot_command* cmd)

cores/esp8266/coredecls.h

@@ -8,6 +8,7 @@ extern "C" {
 
 // TODO: put declarations here, get rid of -Wno-implicit-function-declaration
 
+#include <stddef.h>
 #include <stdint.h>
 #include <cont.h> // g_pcont declaration
 
@@ -20,6 +21,7 @@ void settimeofday_cb (void (*cb)(void));
 void disable_extra4k_at_link_time (void) __attribute__((noinline));
 
 uint32_t sqrt32 (uint32_t n);
+uint32_t crc32 (const void* data, size_t length, uint32_t crc = 0xffffffff);
 
 #ifdef __cplusplus
 }

cores/esp8266/crc32.cpp

@@ -0,0 +1,42 @@
+/*
+ crc32.cpp
+
+ Copyright (c) 2015 Ivan Grokhotkov. All rights reserved.
+ This file is part of the esp8266 core for Arduino environment.
+
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ This library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with this library; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include "coredecls.h"
+
+// moved from core_esp8266_eboot_command.cpp
+uint32_t crc32 (const void* data, size_t length, uint32_t crc /*= 0xffffffff*/)
+{
+    const uint8_t* ldata = (const uint8_t*)data;
+    while (length--)
+    {
+        uint8_t c = *ldata++;
+        for (uint32_t i = 0x80; i > 0; i >>= 1)
+        {
+            bool bit = crc & 0x80000000;
+            if (c & i)
+                bit = !bit;
+            crc <<= 1;
+            if (bit)
+                crc ^= 0x04c11db7;
+        }
+    }
+    return crc;
+}