| 1 | //===-- lib/runtime/buffer.cpp ----------------------------------*- C++ -*-===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |
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| 9 | #include "flang-rt/runtime/buffer.h" |
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| 10 | #include <algorithm> |
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| 11 | |
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| 12 | namespace Fortran::runtime::io { |
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| 13 | RT_OFFLOAD_API_GROUP_BEGIN |
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| 14 | |
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| 15 | // Here's a very old trick for shifting circular buffer data cheaply |
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| 16 | // without a need for a temporary array. |
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| 17 | void LeftShiftBufferCircularly( |
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| 18 | char *buffer, std::size_t bytes, std::size_t shift) { |
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| 19 | // Assume that we start with "efgabcd" and the left shift is 3. |
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| 20 | RT_DIAG_PUSH |
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| 21 | RT_DIAG_DISABLE_CALL_HOST_FROM_DEVICE_WARN |
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| 22 | std::reverse(buffer, buffer + shift); // "gfeabcd" |
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| 23 | std::reverse(first: buffer, last: buffer + bytes); // "dcbaefg" |
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| 24 | std::reverse(first: buffer, last: buffer + bytes - shift); // "abcdefg" |
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| 25 | RT_DIAG_POP |
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| 26 | } |
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| 27 | |
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| 28 | RT_OFFLOAD_API_GROUP_END |
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| 29 | } // namespace Fortran::runtime::io |
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| 30 | |
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