diff options
Diffstat (limited to 'libbutl/lz4.hxx')
| -rw-r--r-- | libbutl/lz4.hxx | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/libbutl/lz4.hxx b/libbutl/lz4.hxx index 98175c1..cfe9967 100644 --- a/libbutl/lz4.hxx +++ b/libbutl/lz4.hxx @@ -30,8 +30,9 @@ namespace butl // The output and most likely the input streams must be in the binary // mode. // - // Valid values for the compressions level are between 1 (fastest) and - // 12 (best compression level). + // Valid values for the compression level are between 1 (fastest) and 12 + // (best compression level) though, practically, after 9 returns are + // diminished. // // Valid block sizes and their IDs: // @@ -40,6 +41,10 @@ namespace butl // 6: 1MB // 7: 4MB // + // Note that due to the underlying API limitations, 0 content size is + // treated as absent and it's therefore impossible to compress 0-byte + // content with content size. + // // This function produces compressed content identical to: // // lz4 -z -<compression_level> -B<block_size_id> -BD [--content-size] @@ -120,8 +125,8 @@ namespace butl // This function may throw std::bad_alloc as well as exceptions thrown by // fdstream read/write functions. It may also throw std::invalid_argument // if the compressed content is invalid with what() returning the error - // description. The input stream is expected to throw on badbit (but not - // failbit). The output stream is expected to throw on badbit or failbit. + // description. The input stream is expected to throw on badbit but not + // failbit. The output stream is expected to throw on badbit or failbit. // // The input and most likely the output streams must be in the binary // mode. @@ -162,6 +167,8 @@ namespace butl // function sets the required input and output buffer capacities (ic, // oc) and the number of bytes left in the header buffer (hn) and // returns the number of bytes expected by the following call to next(). + // If content_size is not NULL, then it is set to the decompressed + // content size, if available. // // The caller normally allocates the input and output buffers, copies // remaining header buffer data over to the input buffer, and then fills @@ -169,7 +176,7 @@ namespace butl // call to next(). // std::size_t - begin (); + begin (optional<std::uint64_t>* content_size = nullptr); // Then call next() to decompress the next chunk of input. This function // returns the number of bytes expected by the following call to next() @@ -188,7 +195,7 @@ namespace butl // Implementation details. // - decompressor (); + decompressor (): hn (0), in (0), on (0), ctx_ (nullptr) {} ~decompressor (); public: |