| Diana Picus | 651f58b | 2021-09-02 08:14:01 | [diff] [blame] | 1 | //===-- runtime/buffer.cpp ------------------------------------------------===// |
| peter klausler | f7be251 | 2020-01-24 00:59:27 | [diff] [blame] | 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | |
| 9 | #include "buffer.h" |
| 10 | #include <algorithm> |
| 11 | |
| 12 | namespace Fortran::runtime::io { |
| 13 | |
| 14 | // Here's a very old trick for shifting circular buffer data cheaply |
| 15 | // without a need for a temporary array. |
| 16 | void LeftShiftBufferCircularly( |
| 17 | char *buffer, std::size_t bytes, std::size_t shift) { |
| 18 | // Assume that we start with "efgabcd" and the left shift is 3. |
| Tim Keith | 1f87900 | 2020-03-29 04:00:16 | [diff] [blame] | 19 | std::reverse(buffer, buffer + shift); // "gfeabcd" |
| 20 | std::reverse(buffer, buffer + bytes); // "dcbaefg" |
| 21 | std::reverse(buffer, buffer + bytes - shift); // "abcdefg" |
| peter klausler | f7be251 | 2020-01-24 00:59:27 | [diff] [blame] | 22 | } |
| Tim Keith | 1f87900 | 2020-03-29 04:00:16 | [diff] [blame] | 23 | } // namespace Fortran::runtime::io |
