third_party/pigweed/repo/pw_kvs/alignment.cc

   1 // Copyright 2020 The Pigweed Authors
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not
   4 // use this file except in compliance with the License. You may obtain a copy of
   5 // the License at
   6 //
   7 //     https://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  12 // License for the specific language governing permissions and limitations under
  13 // the License.
  14
  15 #include "pw_kvs/alignment.h"
  16
  17 #include "pw_status/try.h"
  18
  19 namespace pw {
  20
  21 StatusWithSize AlignedWriter::Write(std::span<const std::byte> data) {
  22   while (!data.empty()) {
  23     size_t to_copy = std::min(write_size_ - bytes_in_buffer_, data.size());
  24
  25     std::memcpy(&buffer_[bytes_in_buffer_], data.data(), to_copy);
  26     PW_TRY_WITH_SIZE(AddBytesToBuffer(to_copy));
  27     data = data.subspan(to_copy);
  28   }
  29
  30   return StatusWithSize(bytes_written_);
  31 }
  32
  33 StatusWithSize AlignedWriter::Flush() {
  34   Status status;
  35
  36   // If data remains in the buffer, pad it to the alignment size and flush the
  37   // remaining data.
  38   if (bytes_in_buffer_ != 0u) {
  39     const size_t remaining_bytes = AlignUp(bytes_in_buffer_, alignment_bytes_);
  40     std::memset(&buffer_[bytes_in_buffer_],
  41                 int(kPadByte),
  42                 remaining_bytes - bytes_in_buffer_);
  43     status = output_.Write(buffer_, remaining_bytes).status();
  44
  45     bytes_written_ += remaining_bytes;  // Include padding in the total.
  46     bytes_in_buffer_ = 0;
  47   }
  48
  49   const StatusWithSize result(status, bytes_written_);
  50   bytes_written_ = 0;
  51   return result;
  52 }
  53
  54 StatusWithSize AlignedWriter::Write(Input& input, size_t size) {
  55   while (size > 0u) {
  56     const size_t to_read = std::min(write_size_ - bytes_in_buffer_, size);
  57     StatusWithSize result = input.Read(buffer_ + bytes_in_buffer_, to_read);
  58     if (!result.ok()) {
  59       return StatusWithSize(result.status(), bytes_written_);
  60     }
  61     PW_TRY_WITH_SIZE(AddBytesToBuffer(to_read));
  62     size -= result.size();
  63   }
  64
  65   return StatusWithSize(bytes_written_);
  66 }
  67
  68 StatusWithSize AlignedWriter::AddBytesToBuffer(size_t bytes_added) {
  69   bytes_in_buffer_ += bytes_added;
  70
  71   // If the buffer is full, write it out.
  72   if (bytes_in_buffer_ == write_size_) {
  73     StatusWithSize result = output_.Write(buffer_, write_size_);
  74
  75     // Always use write_size_ for the bytes written. If there was an error
  76     // assume the space was written or at least disturbed.
  77     bytes_written_ += write_size_;
  78     bytes_in_buffer_ = 0;
  79
  80     if (!result.ok()) {
  81       return StatusWithSize(result.status(), bytes_written_);
  82     }
  83   }
  84
  85   return StatusWithSize(bytes_written_);
  86 }
  87
  88 }  // namespace pw