86 lines
3.0 KiB
C
86 lines
3.0 KiB
C
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#pragma once
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#include <uzlib.h>
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#include <cstddef>
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// Return value for readAtMost().
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enum class InflateStatus {
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Ok, // Output buffer full; more compressed data remains.
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Done, // Stream ended cleanly (TINF_DONE). produced may be < maxLen.
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Error, // Decompression failed.
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};
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// Streaming deflate decompressor wrapping uzlib.
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//
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// Two modes:
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// init(false) — one-shot: input is a contiguous buffer, call read() once.
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// init(true) — streaming: allocates a 32KB ring buffer for back-references
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// across multiple read() / readAtMost() calls.
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//
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// Streaming callback pattern:
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// The uzlib read callback receives a `struct uzlib_uncomp*` with no separate
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// context pointer. To attach context, make InflateReader the *first member* of
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// your context struct, then cast inside the callback:
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//
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// struct MyCtx {
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// InflateReader reader; // must be first
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// FsFile* file;
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// // ...
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// };
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// static int myCb(struct uzlib_uncomp* u) {
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// MyCtx* ctx = reinterpret_cast<MyCtx*>(u); // valid: reader.decomp is at offset 0
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// // ... fill u->source / u->source_limit, return first byte
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// }
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// MyCtx ctx;
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// ctx.reader.init(true);
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// ctx.reader.setReadCallback(myCb);
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//
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class InflateReader {
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public:
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InflateReader() = default;
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~InflateReader();
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InflateReader(const InflateReader&) = delete;
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InflateReader& operator=(const InflateReader&) = delete;
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// Initialise decompressor. streaming=true allocates a 32KB ring buffer needed
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// when read() or readAtMost() will be called multiple times.
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// Returns false only in streaming mode if the ring buffer allocation fails.
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bool init(bool streaming = false);
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// Release the ring buffer and reset internal state.
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void deinit();
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// Set the entire compressed input as a contiguous memory buffer.
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// Used in one-shot mode; not needed when a read callback is set.
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void setSource(const uint8_t* src, size_t len);
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// Set a uzlib-compatible read callback for streaming input.
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// See class-level comment for the expected callback/context struct pattern.
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void setReadCallback(int (*cb)(uzlib_uncomp*));
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// Consume the 2-byte zlib header (CMF + FLG) from the input stream.
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// Call this once before the first read() when input is zlib-wrapped (e.g. PNG IDAT).
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void skipZlibHeader();
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// Decompress exactly len bytes into dest.
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// Returns false if the stream ends before producing len bytes, or on error.
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bool read(uint8_t* dest, size_t len);
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// Decompress up to maxLen bytes into dest.
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// Sets *produced to the number of bytes written.
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// Returns Done when the stream ends cleanly, Ok when there is more to read,
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// and Error on failure.
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InflateStatus readAtMost(uint8_t* dest, size_t maxLen, size_t* produced);
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// Returns a pointer to the underlying TINF_DATA.
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// Useful for advanced streaming setups where the callback needs access to the
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// uzlib struct directly (e.g. updating source/source_limit).
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uzlib_uncomp* raw() { return &decomp; }
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private:
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uzlib_uncomp decomp = {};
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uint8_t* ringBuffer = nullptr;
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};
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