add _zstd cython module

game_backuper/_zstd.pxd

@@ -0,0 +1,46 @@
+from libc.stddef cimport size_t
+
+
+cdef extern from "zstd.h":
+    ctypedef struct ZSTD_CCtx:
+        pass
+    ctypedef ZSTD_CCtx ZSTD_CStream
+    ctypedef enum ZSTD_EndDirective:
+        ZSTD_e_continue = 0
+        ZSTD_e_flush = 1
+        ZSTD_e_end = 2
+    cdef struct ZSTD_inBuffer_s:
+        const void* src
+        size_t size
+        size_t pos
+    ctypedef ZSTD_inBuffer_s ZSTD_inBuffer
+    cdef struct ZSTD_outBuffer_s:
+        void* dst
+        size_t size
+        size_t pos
+    ctypedef ZSTD_outBuffer_s ZSTD_outBuffer
+    ctypedef enum ZSTD_cParameter:
+        ZSTD_c_compressionLevel
+        ZSTD_c_checksumFlag
+    ctypedef struct ZSTD_DCtx:
+        pass
+    ctypedef ZSTD_DCtx ZSTD_DStream
+
+    const char* ZSTD_versionString()
+    unsigned ZSTD_isError(size_t code)
+    const char* ZSTD_getErrorName(size_t code)
+    int ZSTD_maxCLevel()
+    ZSTD_CCtx* ZSTD_createCCtx()
+    size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx)
+    ZSTD_CStream* ZSTD_createCStream()
+    size_t ZSTD_freeCStream(ZSTD_CStream* zcs)
+    size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel)
+    size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, int value)
+    size_t ZSTD_CStreamInSize()
+    size_t ZSTD_CStreamOutSize()
+    size_t ZSTD_DStreamInSize()
+    size_t ZSTD_DStreamOutSize()
+    size_t ZSTD_compressStream2(ZSTD_CCtx* cctx, ZSTD_outBuffer* output, ZSTD_inBuffer* inp, ZSTD_EndDirective endOp)
+    ZSTD_DCtx* ZSTD_createDCtx()
+    size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx)
+    size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* inp)