From 4c757935082a85dc5a26569335f5a098d7f46cda Mon Sep 17 00:00:00 2001
From: Ivan Grokhotkov <igrokhotkov@gmail.com>
Date: Sun, 14 Feb 2016 22:16:46 +0300
Subject: [PATCH] Fix undefined reference to putchar

---
 cores/esp8266/libc_replacements.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/cores/esp8266/libc_replacements.c b/cores/esp8266/libc_replacements.c
index 964e84521..57fbed9c9 100644
--- a/cores/esp8266/libc_replacements.c
+++ b/cores/esp8266/libc_replacements.c
@@ -44,6 +44,13 @@ int ICACHE_RAM_ATTR puts(const char * str) {
     return ets_printf("%s", str);
 }
 
+// newlib has 'putchar' defined to a big scary construct
+#undef putchar
+
+int ICACHE_RAM_ATTR putchar(int c) {
+    return ets_putc(c);
+}
+
 int ICACHE_RAM_ATTR printf(const char* format, ...) {
     int ret;
     va_list arglist;