Deflate.h

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#ifndef CASACORE_SISCO_DEFLATE_H_
#define CASACORE_SISCO_DEFLATE_H_
 
#include "libdeflate.h"
 
#include <cstddef>
#include <span>
#include <stdexcept>
 
namespace casacore::deflate {
 
class Compressor {
 public:
  Compressor(int compression_level)
      : compressor_(libdeflate_alloc_compressor(compression_level)) {
    if (!compressor_)
      throw std::runtime_error(
          "Could not create compressor: bad settings or out of memory");
  }
 
  Compressor(int compression_level, const libdeflate_options& options)
      : compressor_(
            libdeflate_alloc_compressor_ex(compression_level, &options)) {
    if (!compressor_)
      throw std::runtime_error(
          "Could not create compressor: bad settings or out of memory");
  }
 
  ~Compressor() { libdeflate_free_compressor(compressor_); }

  size_t Compress(std::span<const std::byte> input,
                  std::span<std::byte> output) {
    return libdeflate_deflate_compress(compressor_, input.data(), input.size(),
                                       output.data(), output.size());
  }

  size_t CompressBound(size_t input_size) {
    return libdeflate_deflate_compress_bound(compressor_, input_size);
  }
 
 private:
  struct libdeflate_compressor* compressor_;
};
 
class Decompressor {
 public:
  Decompressor() : decompressor_(libdeflate_alloc_decompressor()) {
    if (!decompressor_)
      throw std::runtime_error(
          "Could not create decompressor: bad settings or out of memory");
  }
 
  Decompressor(const libdeflate_options& options)
      : decompressor_(libdeflate_alloc_decompressor_ex(&options)) {
    if (!decompressor_)
      throw std::runtime_error(
          "Could not create decompressor: bad settings or out of memory");
  }
 
  ~Decompressor() { libdeflate_free_decompressor(decompressor_); }
 
  size_t Decompress(std::span<const std::byte> input,
                    std::span<std::byte> output) {
    size_t actual_out_nbytes_ret;
    const libdeflate_result result = libdeflate_deflate_decompress(
        decompressor_, input.data(), input.size(), output.data(), output.size(),
        &actual_out_nbytes_ret);
    switch (result) {
      case LIBDEFLATE_SUCCESS:
        break;
      case LIBDEFLATE_BAD_DATA:
        throw std::runtime_error("Could not decompress data: bad data");
      case LIBDEFLATE_SHORT_OUTPUT:
        throw std::runtime_error(
            "Could not decompress data: data shorter than expected");
      case LIBDEFLATE_INSUFFICIENT_SPACE:
        throw std::runtime_error(
            "Could not decompress data: insufficient space in output buffer");
    }
    return actual_out_nbytes_ret;
  }
 
 private:
  struct libdeflate_decompressor* decompressor_;
};
 
}  // namespace casacore::deflate
 
#endif