Move base32 into base so that it can be used within base.

components/base32/base32.cc

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "components/base32/base32.h"
-
-#include <stddef.h>
-#include <algorithm>
-#include <limits>
-
-#include "base/logging.h"
-
-namespace base32 {
-
-namespace {
-constexpr char kEncoding[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
-}  // namespace
-
-std::string Base32Encode(base::StringPiece input, Base32EncodePolicy policy) {
-  if (input.empty())
-    return std::string();
-
-  if (input.size() > std::numeric_limits<size_t>::max() / 8) {
-    NOTREACHED()
-        << "Input is too large and would overflow encoded size computation.";
-    return std::string();
-  }
-
-  // Per RFC4648, the output is formed of 8 characters per 40 bits of input and
-  // another 8 characters for the last group of [1,39] bits in the input.
-  // That is: ceil(input.size() * 8.0 / 40.0) * 8 ==
-  //          ceil(input.size() / 5.0) * 8 ==
-  //          ((input.size() + 4) / 5) * 8.
-  const size_t padded_length = ((input.size() + 4) / 5) * 8;
-
-  // When no padding is used, the output is exactly 1 character per 5 bits of
-  // input and one more for the last [1,4] bits.
-  // That is: ceil(input.size() * 8.0 / 5.0) ==
-  //          (input.size() * 8 + 4) / 5.
-  const size_t unpadded_length = (input.size() * 8 + 4) / 5;
-
-  std::string output;
-  const size_t encoded_length = policy == Base32EncodePolicy::INCLUDE_PADDING
-                                    ? padded_length
-                                    : unpadded_length;
-  output.reserve(encoded_length);
-
-  // A bit stream which will be read from the left and appended to from the
-  // right as it's emptied.
-  uint16_t bit_stream = (static_cast<uint8_t>(input[0]) << 8);
-  size_t next_byte_index = 1;
-  int free_bits = 8;
-  while (free_bits < 16) {
-    // Extract the 5 leftmost bits in the stream
-    output.push_back(kEncoding[(bit_stream & 0xf800) >> 11]);
-    bit_stream <<= 5;
-    free_bits += 5;
-
-    // If there is enough room in the bit stream, inject another byte (if there
-    // are any left...).
-    if (free_bits >= 8 && next_byte_index < input.size()) {
-      free_bits -= 8;
-      bit_stream += static_cast<uint8_t>(input[next_byte_index++]) << free_bits;
-    }
-  }
-
-  if (policy == Base32EncodePolicy::INCLUDE_PADDING) {
-    output.append(padded_length - unpadded_length, '=');
-  }
-
-  DCHECK_EQ(encoded_length, output.size());
-  return output;
-}
-
-}  // namespace base32