playing with zlib

experimental/compress.lua

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+--[[
+    Implementation of compress routine from zlib
+    https://github.com/madler/zlib
+]]
+
+--[[
+    compress2
+
+    dest        Bytef *
+    destlen     uLongf *
+    source      const Bytef *
+    sourceLen   uLong
+    level       int
+]]
+local function compress2(dest, destLen, source, sourceLen, level)
+    local stream
+    local err
+    local max = math.hugemin
+    local left = destLen;
+    destLen = 0
+
+    local err = deflateInit(stream, level)
+    if err ~= Z_OK then
+        return err;
+    end
+
+    stream.next_out = dest;
+    stream.avail_out = 0;
+    stream.next_in = (z_const Byteef *)source
+    stream.avail_in = 0;
+
+    do
+    while err == Z_OK
+
+    *destLen = stream.total_out;
+    deflateEnd(stream)
+
+    return err == Z_STREAM_END ? Z_OK : err
+end
+
+local function compress(dest, destLen, source, sourceLen)
+    return compress2(dest, destLen, source, sourceLen, Z_DEFAULT_COMPRESSION)
+end
+
+local function compressBound(sourceLen)
+    return sourceLen + rshift(sourceLen, 12) + rshift(sourceLen, 14) +
+    rshift(sourceLen, 25) + 13;
+end
+
+return {
+    compress = compress;
+    compress2 = compress2;
+    compressBound = compressBound;
+}

experimental/deflate.lua

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+--[[
+    zlib implementation of deflate
+
+    https://github.com/madler/zlib/blob/master/deflate.h
+]]
+local ffi = require("ffi")
+
+local zutil = require("zutil")
+
+local ex = {
+    LENGTH_CODES = 29;
+    LITERALS = 256;
+    D_CODES = 30;
+    BL_CODES = 19;
+    MAX_BITS = 15;
+    Buf_size = 16;
+    INIT_STATE = 42;
+    GZIP_STATE = 57;
+    EXTRA_STATE = 69;
+    NAME_STATE = 73;
+    COMMENT_STATE = 91;
+    HCRC_STATE = 103;
+    BUSY_STATE = 113;
+    FINISH_STATE = 666;     -- stream complete
+}
+
+
+ex.L_CODES = ex.LITERALS+1+ex.LENGTH_CODES;
+ex.HEAP_SIZE = 2*ex.L_CODES+1;
+
+ffi.cdef[[
+typedef struct ct_data_s {
+    union {
+        ush freq;   // frequency count for huffman
+        ush code;   // bit string
+    } fc;
+
+    union {
+        ush dad;    // father node in huffman tree
+        ush len;    // length of bit string
+    } dl;
+} ct_data;
+]]
+
+
+ffi.cdef[[
+    typedef struct static_tree_desc_s static_tree_desc;
+
+typedef struct tree_desc_s {
+    ct_data *dyn_tree;
+    int max_code;
+    const static_tree_desc *stat_desc;
+}
+]]
+
+ffi.cdef[[
+typedef ush Pos;
+typedef Pos Posf;
+typedef unsigned IPos;
+]]
+
+
+
+
+return ex

experimental/zutil.lua

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+local ffi = require("ffi")
+
+ffi.cdef[[
+typedef unsigned char uch;
+typedef uch echf;
+typedef unsigned short ush;
+typedef ush ushf;
+typedef unsigned long ulg;
+]]