From da62ebc152c3a7a7699e84f9b007fc9ff0f80df0 Mon Sep 17 00:00:00 2001
From: Tomasz Scislowicz <toomasz@gmail.com>
Date: Wed, 19 Sep 2018 22:00:16 +0200
Subject: [PATCH 1/2] getFreeSysStack implementation

---
 cores/esp8266/Esp.cpp | 5 +++++
 cores/esp8266/Esp.h   | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/cores/esp8266/Esp.cpp b/cores/esp8266/Esp.cpp
index 1fd8b2c52d..554e4f8a45 100644
--- a/cores/esp8266/Esp.cpp
+++ b/cores/esp8266/Esp.cpp
@@ -183,6 +183,11 @@ uint32_t EspClass::getFreeContStack()
     return cont_get_free_stack(g_pcont);
 }
 
+uint32_t EspClass::getFreeSysStack()
+{
+	register volatile uint32_t stackAddress asm("a1");
+	return stackAddress-SYSTEM_STACK_END_ADDRESS;
+}
 uint32_t EspClass::getChipId(void)
 {
     return system_get_chip_id();
diff --git a/cores/esp8266/Esp.h b/cores/esp8266/Esp.h
index d058f2225c..829d6b720c 100644
--- a/cores/esp8266/Esp.h
+++ b/cores/esp8266/Esp.h
@@ -65,6 +65,9 @@ enum RFMode {
 #define WAKE_NO_RFCAL    RF_NO_CAL
 #define WAKE_RF_DISABLED RF_DISABLED
 
+// for getFreeSysStack
+#define SYSTEM_STACK_END_ADDRESS 0x3FFFC000
+
 enum ADCMode {
     ADC_TOUT = 33,
     ADC_TOUT_3V3 = 33,
@@ -111,6 +114,7 @@ class EspClass {
         void getHeapStats(uint32_t* free = nullptr, uint16_t* max = nullptr, uint8_t* frag = nullptr);
 
         uint32_t getFreeContStack();
+		uint32_t getFreeSysStack();
 
         const char * getSdkVersion();
         String getCoreVersion();

From 434dd97a28990a09ec5fffda98119e0ae3298dfe Mon Sep 17 00:00:00 2001
From: Tomasz Scislowicz <toomasz@gmail.com>
Date: Wed, 19 Sep 2018 22:09:59 +0200
Subject: [PATCH 2/2] space instead of tabs

---
 cores/esp8266/Esp.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cores/esp8266/Esp.h b/cores/esp8266/Esp.h
index 829d6b720c..b05f7817f8 100644
--- a/cores/esp8266/Esp.h
+++ b/cores/esp8266/Esp.h
@@ -114,7 +114,7 @@ class EspClass {
         void getHeapStats(uint32_t* free = nullptr, uint16_t* max = nullptr, uint8_t* frag = nullptr);
 
         uint32_t getFreeContStack();
-		uint32_t getFreeSysStack();
+        uint32_t getFreeSysStack();
 
         const char * getSdkVersion();
         String getCoreVersion();