Provide replacements for malloc, free and other libc functions

#11

cores/esp8266/libc_replacements.c

@@ -0,0 +1,101 @@
+/* 
+  libc_replacements.c - replaces libc functions with functions
+                        from Espressif SDK
+
+  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 <stddef.h>
+#include <stdarg.h>
+
+#include "ets_sys.h"
+#include "os_type.h"
+#include "osapi.h"
+#include "mem.h"
+#include "user_interface.h"
+
+
+void* malloc(size_t size) {
+  return os_malloc(size);
+}
+
+void free(void* ptr) {
+  os_free(ptr);
+}
+
+void* realloc(void* ptr, size_t size) {
+  return os_realloc(ptr, size);
+}
+
+int printf(const char* format, ...) {
+  va_list arglist;
+  va_start(arglist, format);
+  ets_vprintf(format, arglist);
+  va_end(arglist);
+}
+
+int sprintf(char* buffer, const char* format, ...) {
+  va_list arglist;
+  va_start(arglist, format);
+  ets_vsprintf(buffer, format, arglist);
+  va_end(arglist);
+}
+
+int snprintf(char* buffer, size_t size, const char* format, ...) {
+  va_list arglist;
+  va_start(arglist, format);
+  ets_vsnprintf(buffer, size, format, arglist);
+  va_end(arglist);
+}
+
+int memcmp(const void *s1, const void *s2, size_t n) {
+  return ets_memcmp(s1, s2, n);
+}
+
+void* memcpy(void *dest, const void *src, size_t n) {
+  return ets_memcpy(dest, src, n);
+}
+
+void* memset(void *s, int c, size_t n) {
+  return ets_memset(s, c, n);
+}
+
+int strcmp(const char *s1, const char *s2) {
+  return ets_strcmp(s1, s2);
+}
+
+char* strcpy(char *dest, const char *src) {
+  return ets_strcpy(dest, src);
+}
+
+size_t strlen(const char *s) {
+  return ets_strlen(s);
+}
+
+int strncmp(const char *s1, const char *s2, size_t len) {
+  return ets_strncmp(s1, s2, len);
+}
+
+char *strncpy(char *dest, const char *src, size_t n) {
+  return ets_strncpy(dest, src, n);
+}
+
+char *ets_strstr(const char *haystack, const char *needle) {
+  return strstr(haystack, needle);
+}
+