/**
* OCaml binding for _zlib_'s `deflateInit2` function.
*
* This creates a new stream and initializes it for deflate.
*
* This function may raise the following OCaml exceptions:
* - Out_of_memory exception
* - Failure exception: Invalid parameters
* - Failure exception: Invalid version
* - Failure exception: Unknown zlib return code
*
* See:
* https://github.com/madler/zlib/blob/cacf7f1d4e3d44d871b605da3b647f07d718623f/zlib.h#L538
*
* @param levelVal {value} OCaml `int`: the compression level, must be in the range 0..9.
* 0 gives no compression at all, 1 the best speed, 9 the best compression.
* @param windowBitsVal {value} OCaml `int`: base two logarithm of the window size (size of the
* history buffer) used by _zlib_. It should be in the range 9..15 for this version of _zlib_.
* It can also be in the range -15..-8 (the absolute value is used) for raw deflate.
* Finally, it can be greater than 15 for gzip encoding. See _zlib_'s documentation for
* `deflateInit2` for the exact documentation.
* @return {value} An OCaml value representing the new stream, initialized for deflate.
*/
CAMLprim value zlib_deflate_init2(value level_val, value window_bits_val) {
int level = Int_val(level_val);
int window_bits = Int_val(window_bits_val);
value z_streamp_val = zlib_new_stream();
z_streamp stream = ZStreamP_val(z_streamp_val);
int deflate_init2_result = deflateInit2(
stream,
level,
Z_DEFLATED, // method
window_bits,
8, // memLevel
Z_DEFAULT_STRATEGY // strategy
);
if (deflate_init2_result == Z_OK) {
return z_streamp_val;
}
switch (deflate_init2_result) {
case Z_MEM_ERROR:
caml_raise_out_of_memory();
break;
case Z_STREAM_ERROR:
// TODO: use stream->msg to get _zlib_'s text message
failwith("Error in `zlib_deflate_init2` (extc_stubs.c): call to `deflateInit2` failed: Z_STREAM_ERROR");
break;
case Z_VERSION_ERROR:
// TODO: use stream->msg to get _zlib_'s text message
failwith("Error in `zlib_deflate_init2` (extc_stubs.c): call to `deflateInit2` failed: Z_VERSION_ERROR");
break;
default:
failwith("Error in `zlib_deflate_init2` (extc_stubs.c): unknown return code from `deflateInit2`");
}
assert(0);
}
CAMLprim value zlib_inflate_init(value wbits) {
value z = zlib_new_stream();
if( inflateInit2(ZStreamP_val(z),Int_val(wbits)) != Z_OK )
failwith("zlib_inflate_init");
return z;
}
CAMLprim value zlib_deflate_init2(value lvl,value wbits) {
value z = zlib_new_stream();
if( deflateInit2(zval(z),Int_val(lvl),Z_DEFLATED,Int_val(wbits),8,Z_DEFAULT_STRATEGY) != Z_OK )
failwith("zlib_deflate_init");
return z;
}
