First batch of opensdk additions

Replacements for:
    libmain/misc.o
    libmain/os_cpu_a.o
    libmain/spi_flash.o
    libmain/timers.o
    libmain/uart.o
    libmain/xtensa_context.o

core/include/flashchip.h

@@ -0,0 +1,39 @@
+/* flashchip.h
+ *
+ * sdk_flashchip_t structure used by the SDK and some bootrom routines
+ *
+ * This is in a separate include file because it's referenced by several other
+ * headers which are otherwise independent of each other.
+ *
+ * Part of esp-open-rtos
+ * Copyright (C) 2015 Alex Stewart and Angus Gratton
+ * BSD Licensed as described in the file LICENSE
+ */
+
+#ifndef _FLASHCHIP_H
+#define _FLASHCHIP_H
+
+/* SDK/bootrom uses this structure internally to account for flash size.
+
+   chip_size field is initialised during startup from the flash size
+   saved in the image header (on the first 8 bytes of SPI flash).
+
+   Other field are initialised to hardcoded values by the SDK.
+
+   ** NOTE: This structure is passed to some bootrom routines and is therefore
+   fixed.  Be very careful if you want to change it that you do not break
+   things. **
+
+   Based on RE work by @foogod at
+   http://esp8266-re.foogod.com/wiki/Flashchip_%28IoT_RTOS_SDK_0.9.9%29
+*/
+typedef struct {
+    uint32_t device_id;
+    uint32_t chip_size;   /* in bytes */
+    uint32_t block_size;  /* in bytes */
+    uint32_t sector_size; /* in bytes */
+    uint32_t page_size;   /* in bytes */
+    uint32_t status_mask;
+} sdk_flashchip_t;
+
+#endif /* _FLASHCHIP_H */