Added first half of RE'd user_interface.c

core/include/esp/sar_regs.h

@@ -0,0 +1,39 @@
+/* esp/sar_regs.h
+ *
+ * ESP8266 register definitions for the "sar" region (0x3FF2xxx)
+ *
+ * The 0x60000D00 register region is referred to as "sar" by some old header
+ * files. Apparently referenced both by ROM I2C functions as well as ADC
+ * config/read functions.
+ *
+ * Not compatible with ESP SDK register access code.
+ */
+
+#ifndef _ESP_SAR_REGS_H
+#define _ESP_SAR_REGS_H
+
+#include "esp/types.h"
+#include "common_macros.h"
+
+#define SAR_BASE 0x60000d00
+// Unfortunately,
+// esp-open-sdk/xtensa-lx106-elf/xtensa-lx106-elf/sysroot/usr/include/xtensa/config/specreg.h
+// already has a "SAR" macro definition which would conflict with this, so
+// we'll use "ESPSAR" instead..
+#define ESPSAR (*(struct SAR_REGS *)(SAR_BASE))
+
+/* Note: This memory region is not currently well understood.  Pretty much all
+ * of the definitions here are from reverse-engineering the Espressif SDK code,
+ * many are just educated guesses, and almost certainly some are misleading or
+ * wrong.  If you can improve on any of this, please contribute!
+ */
+
+struct SAR_REGS {
+    uint32_t volatile _unknown0[18];   // 0x00 - 0x44
+    uint32_t volatile UNKNOWN_48;      // 0x48 : used by sdk_system_restart_in_nmi()
+} __attribute__ (( packed ));
+
+_Static_assert(sizeof(struct SAR_REGS) == 0x4c, "SAR_REGS is the wrong size");
+
+#endif /* _ESP_SAR_REGS_H */
+