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diff --git a/scripts/update_payload/format_utils.py b/scripts/update_payload/format_utils.py
new file mode 100644
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+++ b/scripts/update_payload/format_utils.py
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+# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Various formatting functions."""
+
+
+def NumToPercent(num, total, min_precision=1, max_precision=5):
+  """Returns the percentage (string) of |num| out of |total|.
+
+  If the percentage includes a fraction, it will be computed down to the least
+  precision that yields a non-zero and ranging between |min_precision| and
+  |max_precision|. Values are always rounded down. All arithmetic operations
+  are integer built-ins. Examples (using default precision):
+
+    (1, 1) => 100%
+    (3, 10) => 30%
+    (3, 9) => 33.3%
+    (3, 900) => 0.3%
+    (3, 9000000) => 0.00003%
+    (3, 900000000) => 0%
+    (5, 2) => 250%
+
+  Args:
+    num: the value of the part
+    total: the value of the whole
+    min_precision: minimum precision for fractional percentage
+    max_precision: maximum precision for fractional percentage
+  Returns:
+    Percentage string.
+
+  """
+  percent = 0
+  precision = min(min_precision, max_precision)
+  factor = 10 ** precision
+  while precision <= max_precision:
+    percent = num * 100 * factor / total
+    if percent:
+      break
+    factor *= 10
+    precision += 1
+
+  whole, frac = divmod(percent, factor)
+  while frac and not frac % 10:
+    frac /= 10
+    precision -= 1
+
+  return '%d%s%%' % (whole, '.%0*d' % (precision, frac) if frac else '')
+
+
+def BytesToHumanReadable(size, precision=1, decimal=False):
+  """Returns a human readable representation of a given |size|.
+
+  The returned string includes unit notations in either binary (KiB, MiB, etc)
+  or decimal (kB, MB, etc), based on the value of |decimal|. The chosen unit is
+  the largest that yields a whole (or mixed) number. It may contain up to
+  |precision| fractional digits. Values are always rounded down. Largest unit
+  is an exabyte. All arithmetic operations are integer built-ins. Examples
+  (using default precision and binary units):
+
+    4096 => 4 KiB
+    5000 => 4.8 KiB
+    500000 => 488.2 KiB
+    5000000 => 4.7 MiB
+
+  Args:
+    size: the size in bytes
+    precision: the number of digits past the decimal point
+    decimal: whether to compute/present decimal or binary units
+  Returns:
+    Readable size string, or None if no conversion is applicable (i.e. size is
+    less than the smallest unit).
+
+  """
+  constants = (
+      (('KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB'), 1024),
+      (('kB', 'MB', 'GB', 'TB', 'PB', 'EB'), 1000)
+  )
+  suffixes, base = constants[decimal]
+  exp, magnitude = 0, 1
+  while exp < len(suffixes):
+    next_magnitude = magnitude * base
+    if size < next_magnitude:
+      break
+    exp += 1
+    magnitude = next_magnitude
+
+  if exp != 0:
+    whole = size / magnitude
+    frac = (size % magnitude) * (10 ** precision) / magnitude
+    while frac and not frac % 10:
+      frac /= 10
+    return '%d%s %s' % (whole, '.%d' % frac if frac else '', suffixes[exp - 1])