janwas
c4e3037e60
fix crashdumps: was failing to write out to file (underlying cause: current directory no longer being set) app_hooks: add get_log_dir; used by debug and wdbg_sym minor improvements/documentation in archive+compression+file_cache+zip main: remove dead ScEd code This was SVN commit r3498.
66 lines
2.6 KiB
C
66 lines
2.6 KiB
C
#ifndef COMPRESSION_H__
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#define COMPRESSION_H__
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enum ContextType
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{
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CT_COMPRESSION,
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CT_DECOMPRESSION
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};
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enum CompressionMethod
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{
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CM_NONE,
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// zlib "deflate" - see RFC 1750, 1751.
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CM_DEFLATE
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};
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extern uintptr_t comp_alloc(ContextType type, CompressionMethod method);
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// set output buffer. all subsequent comp_feed() calls will write into it.
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// should only be called once (*) due to the comp_finish() interface - since
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// that allows querying the output buffer, it must not be fragmented.
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// * the previous output buffer is wiped out by comp_reset, so
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// setting it again (once!) after that is allowed and required.
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extern void comp_set_output(uintptr_t ctx, void* out, size_t out_size);
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// [compression contexts only:] allocate an output buffer big enough to
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// hold worst_case_compression_ratio*in_size bytes.
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// rationale: this interface is useful because callers cannot
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// reliably estimate how much output space is needed.
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// raises a warning for decompression contexts because this operation
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// does not make sense there:
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// - decompression ratio is quite large - ballpark 1000x;
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// - exact uncompressed size is known to caller (via archive file header).
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// note: buffer is held until comp_free; it can be reused after a
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// comp_reset. this reduces malloc/free calls.
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extern LibError comp_alloc_output(uintptr_t ctx, size_t in_size);
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// get current position in output buffer.
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// precondition: valid calls to EITHER comp_alloc_output OR comp_set_output.
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extern void* comp_get_output(uintptr_t ctx);
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// 'feed' the given buffer to the compressor/decompressor.
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// returns number of output bytes produced (*), or a negative LibError code.
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// * 0 is a legitimate return value - this happens if the input buffer is
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// small and the codec hasn't produced any output.
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// note: the buffer may be overwritten or freed immediately after - we take
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// care of copying and queuing any data that remains (e.g. due to
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// lack of output buffer space).
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extern ssize_t comp_feed(uintptr_t ctx, const void* in, size_t in_size);
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// feed any remaining queued input data, finish the compress/decompress and
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// pass back the output buffer.
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extern LibError comp_finish(uintptr_t ctx, void** out, size_t* out_size);
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// prepare this context for reuse. the effect is similar to freeing this
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// context and creating another.
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// rationale: this API avoids reallocating a considerable amount of
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// memory (ballbark 200KB LZ window plus output buffer).
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extern LibError comp_reset(uintptr_t ctx);
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// free this context and all associated memory.
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extern void comp_free(uintptr_t ctx);
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#endif // #ifndef COMPRESSION_H__
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