Added the (possibly modified) Espressif SDK to the project to avoid problems with building. This may not be OK license wise, but who cares

esp_iot_sdk_v1.5.2/include/osapi.h

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2010 Espressif System
+ */
+
+#ifndef _OSAPI_H_
+#define _OSAPI_H_
+
+#include <string.h>
+#include "user_config.h"
+
+#define os_bzero ets_bzero
+#define os_delay_us ets_delay_us
+#define os_install_putc1 ets_install_putc1
+
+#define os_memcmp ets_memcmp
+#define os_memcpy ets_memcpy
+#define os_memmove ets_memmove
+#define os_memset ets_memset
+#define os_strcat strcat
+#define os_strchr strchr
+#define os_strcmp ets_strcmp
+#define os_strcpy ets_strcpy
+#define os_strlen ets_strlen
+#define os_strncmp ets_strncmp
+#define os_strncpy ets_strncpy
+#define os_strstr ets_strstr
+#ifdef USE_US_TIMER
+#define os_timer_arm_us(a, b, c) ets_timer_arm_new(a, b, c, 0)
+#endif
+#define os_timer_arm(timer, time_ms, repeat) ets_timer_arm_new(timer, time_ms, repeat, 1)
+#define os_timer_disarm ets_timer_disarm
+#define os_timer_setfn ets_timer_setfn
+
+#define os_sprintf  ets_sprintf
+#define os_snprintf ets_snprintf
+
+#ifdef USE_OPTIMIZE_PRINTF
+#define os_printf(fmt, ...) do {	\
+	static const char flash_str[] ICACHE_RODATA_ATTR STORE_ATTR = fmt;	\
+	os_printf_plus(flash_str, ##__VA_ARGS__);	\
+	} while(0)
+#else
+#define os_printf	os_printf_plus
+#endif
+
+unsigned long os_random(void);
+int os_get_random(unsigned char *buf, size_t len);
+
+#endif
+