add printf via DEBUG_PORT define see #909

Author: Links2004

src/WebSockets.h

@@ -50,7 +50,10 @@
         DEBUG_ESP_PORT.flush();             \
     }
 #else
-// #define DEBUG_WEBSOCKETS(...) os_printf( __VA_ARGS__ )
+#ifdef DEBUG_PORT
+#define DEBUG_WEBSOCKETS(...) debug_printf( __VA_ARGS__ )
+    void debug_printf(const char *format, ...);
+#endif
 #endif
 #endif
 

src/debug.cpp

@@ -0,0 +1,31 @@
+
+#include "WebSockets.h"
+
+#include <stdarg.h>
+
+#ifdef DEBUG_PORT
+
+void debug_printf(const char *format, ...) {
+    va_list arg;
+    va_start(arg, format);
+    char temp[64];
+    char* buffer = temp;
+    size_t len = vsnprintf(temp, sizeof(temp), format, arg);
+    va_end(arg);
+    if (len > sizeof(temp) - 1) {
+        buffer = new (std::nothrow) char[len + 1];
+        if (!buffer) {
+            return 0;
+        }
+        va_start(arg, format);
+        vsnprintf(buffer, len + 1, format, arg);
+        va_end(arg);
+    }
+    len = DEBUG_PORT.write((const uint8_t*) buffer, len);
+    if (buffer != temp) {
+        delete[] buffer;
+    }
+    return len;
+}
+
+#endif