diff --git a/targets/TARGET_Realtek/TARGET_AMEBA/flash_api.c b/targets/TARGET_Realtek/TARGET_AMEBA/flash_api.c
index 851b7e21552..c8ebf87a07a 100644
--- a/targets/TARGET_Realtek/TARGET_AMEBA/flash_api.c
+++ b/targets/TARGET_Realtek/TARGET_AMEBA/flash_api.c
@@ -15,10 +15,6 @@
  */
 #include "flash_ext.h"
 
-#define FLASH_START       (SPI_FLASH_BASE + FLASH_OFS_START)
-#define FLASH_END         (SPI_FLASH_BASE + FLASH_OFS_END)
-#define FLASH_OFS(addr)   ((addr) - SPI_FLASH_BASE)
-
 int32_t flash_init(flash_t *obj)
 {
     __flash_ext_turnon();
@@ -35,20 +31,25 @@ int32_t flash_free(flash_t *obj)
 
 int32_t flash_erase_sector(flash_t *obj, uint32_t address)
 {
-    __flash_ext_erase_sector(obj, FLASH_OFS(address));
+    flash_ext_erase_sector(obj, address);
 
     return 0;
 }
 
+int32_t flash_read(flash_t *obj, uint32_t address, uint8_t *data, uint32_t size)
+{
+    return flash_ext_stream_read(obj, address, size, data);;
+}
+
 int32_t flash_program_page(flash_t *obj, uint32_t address, const uint8_t *data, uint32_t size)
 {
-    return __flash_ext_stream_write(obj, FLASH_OFS(address), size, data);
+    return flash_ext_stream_write(obj, address, size, data);
 }
 
 uint32_t flash_get_sector_size(const flash_t *obj, uint32_t address)
 {
-    if (address < FLASH_START || address >= FLASH_END)
-        return 0;
+    if (address >= FLASH_OFS_END)
+        return MBED_FLASH_INVALID_SIZE;
 
     return FLASH_SECTOR_SIZE;
 }
@@ -60,7 +61,7 @@ uint32_t flash_get_page_size(const flash_t *obj)
 
 uint32_t flash_get_start_address(const flash_t *obj)
 {
-    return FLASH_START;
+    return FLASH_OFS_START;
 }
 
 uint32_t flash_get_size(const flash_t *obj)
diff --git a/targets/TARGET_Realtek/TARGET_AMEBA/flash_ext.c b/targets/TARGET_Realtek/TARGET_AMEBA/flash_ext.c
index 598966ca7c4..2618ac8f5f6 100644
--- a/targets/TARGET_Realtek/TARGET_AMEBA/flash_ext.c
+++ b/targets/TARGET_Realtek/TARGET_AMEBA/flash_ext.c
@@ -128,7 +128,7 @@ int flash_ext_stream_read(flash_t *obj, uint32_t addr, uint32_t len, uint8_t *da
     __flash_ext_turnon();
 
     SpicWaitWipDoneRefinedRtl8195A(flashobj.SpicInitPara);
-    
+
     offset = addr & 0x03;
     addr = addr & ~0x03;
     pbuf = data;
@@ -189,13 +189,13 @@ int __flash_ext_stream_write(flash_t *obj, uint32_t addr, uint32_t len, const ui
     uint32_t i, offset, word;
     const uint8_t*pbuf;
     uint8_t *ptr;
-    u8 flashtype = 0; 
+    u8 flashtype = 0;
 
     offset = addr & 0x03;
     addr = addr & ~0x03;
     pbuf = data;
     flashtype = flashobj.SpicInitPara.flashtype;
-    
+
     if (offset != 0) {
         word = HAL_READ32(SPI_FLASH_BASE, addr);
         ptr = (uint8_t *)&word + offset;
@@ -207,7 +207,7 @@ int __flash_ext_stream_write(flash_t *obj, uint32_t addr, uint32_t len, const ui
         }
         HAL_WRITE32(SPI_FLASH_BASE, addr, word);
         SpicWaitBusyDoneRtl8195A();
-        
+
         if(flashtype == FLASH_MICRON){
             SpicWaitOperationDoneRtl8195A(flashobj.SpicInitPara);
         } else {
@@ -222,7 +222,7 @@ int __flash_ext_stream_write(flash_t *obj, uint32_t addr, uint32_t len, const ui
                 ((uint32_t)(*(pbuf+2)) << 16) | ((uint32_t)(*(pbuf+3)) << 24);
             HAL_WRITE32(SPI_FLASH_BASE, addr, word);
             SpicWaitBusyDoneRtl8195A();
-            
+
             if(flashtype == FLASH_MICRON){
                 SpicWaitOperationDoneRtl8195A(flashobj.SpicInitPara);
             } else {
@@ -237,7 +237,7 @@ int __flash_ext_stream_write(flash_t *obj, uint32_t addr, uint32_t len, const ui
         while (len >= 4) {
             HAL_WRITE32(SPI_FLASH_BASE, addr, (uint32_t)*((uint32_t *)pbuf));
             SpicWaitBusyDoneRtl8195A();
-            
+
             if(flashtype == FLASH_MICRON){
                 SpicWaitOperationDoneRtl8195A(flashobj.SpicInitPara);
             } else {
@@ -260,7 +260,7 @@ int __flash_ext_stream_write(flash_t *obj, uint32_t addr, uint32_t len, const ui
 
         HAL_WRITE32(SPI_FLASH_BASE, addr, word);
         SpicWaitBusyDoneRtl8195A();
-        
+
         if(flashtype == FLASH_MICRON){
             SpicWaitOperationDoneRtl8195A(flashobj.SpicInitPara);
         } else {
@@ -271,7 +271,7 @@ int __flash_ext_stream_write(flash_t *obj, uint32_t addr, uint32_t len, const ui
     return 0;
 }
 
-int flash_ext_stream_write(flash_t *obj, uint32_t addr, uint32_t len, uint8_t *data)
+int flash_ext_stream_write(flash_t *obj, uint32_t addr, uint32_t len, const uint8_t *data)
 {
     int32_t status;
 
@@ -287,7 +287,7 @@ int flash_stream_read(flash_t *obj, uint32_t addr, uint32_t len, uint8_t *data)
     return flash_ext_stream_read(obj, addr, len, data);
 }
 
-int flash_stream_write(flash_t *obj, uint32_t addr, uint32_t len, uint8_t *data)
+int flash_stream_write(flash_t *obj, uint32_t addr, uint32_t len, const uint8_t *data)
 {
     return flash_ext_stream_write(obj, addr, len, data);
 }
@@ -308,7 +308,7 @@ Users can use either of functions depending on their needs.
 */
 
 int flash_ext_burst_write(flash_t *obj, uint32_t address ,uint32_t length, uint8_t *data)
-{    
+{
     u32 OccuSize;
     u32 ProgramSize;
     u32 PageSize;
@@ -340,7 +340,7 @@ int flash_ext_burst_write(flash_t *obj, uint32_t address ,uint32_t length, uint8
             }
 
             address += ProgramSize;
-            data += ProgramSize;   
+            data += ProgramSize;
             length -= ProgramSize;
             OccuSize = 0;
         } else{
@@ -435,7 +435,7 @@ This function aims to reset the status register, please make sure the operation
 void flash_ext_reset_status(flash_t *obj)
 {
     __flash_ext_turnon();
-    SpicSetFlashStatusRefinedRtl8195A(0, flashobj.SpicInitPara);    
+    SpicSetFlashStatusRefinedRtl8195A(0, flashobj.SpicInitPara);
     SpicWaitWipDoneRefinedRtl8195A(flashobj.SpicInitPara);
     __flash_ext_turnoff();
 }
diff --git a/targets/TARGET_Realtek/TARGET_AMEBA/flash_ext.h b/targets/TARGET_Realtek/TARGET_AMEBA/flash_ext.h
index aed9f266b58..6ad5c799dac 100644
--- a/targets/TARGET_Realtek/TARGET_AMEBA/flash_ext.h
+++ b/targets/TARGET_Realtek/TARGET_AMEBA/flash_ext.h
@@ -25,17 +25,17 @@ extern "C" {
 
 #define FLASH_PAGE_SIZE 256
 #define FLASH_SIZE        0x100000
-#define FLASH_OFS_START   0xc0000
+#define FLASH_OFS_START   0x0
 #define FLASH_OFS_END     (FLASH_OFS_START + FLASH_SIZE)
 
 extern void flash_ext_erase_sector(flash_t *obj, uint32_t address);
 extern void flash_ext_erase_block(flash_t * obj, uint32_t address);
-extern int flash_ext_read_word(flash_t *obj, uint32_t address, uint32_t * data);
+extern int flash_ext_read_word(flash_t *obj, uint32_t address, uint32_t *data);
 extern int flash_ext_write_word(flash_t *obj, uint32_t address, uint32_t data);
-extern int flash_ext_stream_read(flash_t *obj, uint32_t address, uint32_t len, uint8_t * data);
-extern int flash_ext_stream_write(flash_t *obj, uint32_t address, uint32_t len, uint8_t * data);
+extern int flash_ext_stream_read(flash_t *obj, uint32_t address, uint32_t len, uint8_t *data);
+extern int flash_ext_stream_write(flash_t *obj, uint32_t address, uint32_t len, const uint8_t *data);
 extern int flash_stream_read(flash_t *obj, uint32_t addr, uint32_t len, uint8_t *data);
-extern int flash_stream_write(flash_t *obj, uint32_t addr, uint32_t len, uint8_t *data);
+extern int flash_stream_write(flash_t *obj, uint32_t addr, uint32_t len, const uint8_t *data);
 extern void flash_ext_write_protect(flash_t *obj, uint32_t protect);
 extern int flash_ext_get_status(flash_t *obj);
 extern int flash_ext_set_status(flash_t *obj, uint32_t data);