Merge pull request espressif#45 "write_flash: Show actual flash write…

… speed"

With minor modifications to overwrite last status line, print write
offset in completion line.

esptool.py

@@ -585,6 +585,8 @@ def div_roundup(a, b):
             blocks = div_roundup(len(image), esp.ESP_FLASH_BLOCK)
             esp.flash_begin(blocks*esp.ESP_FLASH_BLOCK, address)
             seq = 0
+            written = 0
+            t = time.time()
             while len(image) > 0:
                 print '\rWriting at 0x%08x... (%d %%)' % (address + seq*esp.ESP_FLASH_BLOCK, 100*(seq+1)/blocks),
                 sys.stdout.flush()
@@ -597,7 +599,9 @@ def div_roundup(a, b):
                 esp.flash_block(block, seq)
                 image = image[esp.ESP_FLASH_BLOCK:]
                 seq += 1
-            print
+                written += len(block)
+            t = time.time() - t
+            print '\rWrote %d bytes at 0x%08x in %.1f seconds (%.1f kbit/s)...' % (written, address, t, written / t * 8 / 1000)
         print '\nLeaving...'
         if args.flash_mode == 'dio':
             esp.flash_unlock_dio()