# Compress::Raw::Zlib

📦 std

Low-level interface to the `zlib` compression library. `Compress::Raw::Zlib` is the thin binding layer underneath `Compress::Zlib` and the whole `IO::Compress::*` family. It exposes zlib’s streaming `deflate`/`inflate` state machines directly, plus the `crc32`/`adler32` checksums and the zlib manifest constants. ```perl use Compress::Raw::Zlib; my ($d, $status) = Compress::Raw::Zlib::Deflate->new(); $d->deflate($input, my $output); $d->flush($output); my ($i, $istatus) = Compress::Raw::Zlib::Inflate->new(); $i->inflate($output, my $roundtrip); ``` This is a 1:1 transliteration of `cpan/Compress-Raw-Zlib/Zlib.xs` (upstream 2.222). The Perl half of `Compress/Raw/Zlib.pm` - the `Parameters` option parser and the `Deflate`/`Inflate`/`InflateScan` constructors - is embedded verbatim and injected with `eval_pv_boot`, the same faithful-mirror technique `B.rs` uses for `B.pm`. zlib itself is reached through `dlopen` (`libz.so.1`), exactly the library the upstream XS links against. No DEFLATE implementation lives here. ## Functions ### Other Functions #### `ret_iv` typemap `T_IV`: `sv_setiv(TARG, (IV)RETVAL); ST(0) = TARG;` #### `ret_uv` typemap `T_UV`: xsubpp emits `TARGu((IV)RETVAL, 1); ST(0) = TARG;` #### `ret_pv` typemap `T_PV`: `sv_setpv((SV*)TARG, RETVAL); ST(0) = TARG;` A NULL RETVAL sets undef - which is what `msg()` wants. #### `ret_bool` typemap `T_BOOL`: `ST(0) = boolSV(RETVAL);` #### `ret_dual` typemap `T_DUAL` (DualType): `SV * RETVALSV = sv_newmortal(); setDUALstatus(RETVALSV, RETVAL); ST(0) = RETVALSV;`