move flash_write and flush to seperate files for other usage

src/flash.h

@@ -0,0 +1,58 @@
+/**************************************************************************/
+/*!
+    @file     flash.h
+    @author   hathach (tinyusb.org)
+
+    @section LICENSE
+
+    Software License Agreement (BSD License)
+
+    Copyright (c) 2018, Adafruit Industries (adafruit.com)
+    All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions are met:
+    1. Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in the
+    documentation and/or other materials provided with the distribution.
+    3. Neither the name of the copyright holders nor the
+    names of its contributors may be used to endorse or promote products
+    derived from this software without specific prior written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
+    EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
+    DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+    ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+/**************************************************************************/
+
+#ifndef FLASH_H_
+#define FLASH_H_
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "nrf_nvmc.h"
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+//void flash_erase(uint32_t page_addr);
+void flash_write(uint32_t dst, const uint8_t *src, int len);
+void flash_flush(void);
+
+
+#ifdef __cplusplus
+ }
+#endif
+
+#endif /* FLASH_H_ */