Finally remove the hardcoded link between
compression helpers and zlib.
Association bewteen a stream and the compression library
is done at stream init time through a set of function
pointers. Library choice is based on compression level
parameter passed to compress_alloc(), this allow us to
stay 100% back compatible with current code.
Patch also adds the the necessary zlib engine plugin,
this turns out to be trivial since we have modeled
everything around zlib.
Signed-off-by: Marco Costalba <mcostalba@xxxxxxxxx>
---
compress.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++---------
compress.h | 6 ++++++
2 files changed, 52 insertions(+), 9 deletions(-)
diff --git a/compress.c b/compress.c
index b28c389..09a5df0 100644
--- a/compress.c
+++ b/compress.c
@@ -1,6 +1,41 @@
#include "cache.h"
#include "compress.h"
+/* Default zlib engine plugin definition
+ *
+ * Because everything is modeled after zlib the
+ * corresponding engine wrappers here are trivial
+ */
+static int zlib_deflateInit(z_stream *s, int l) { return deflateInit(s, l); }
+static int zlib_deflate(z_stream *s, int f) { return deflate(s, f); }
+static int zlib_deflateEnd(z_stream *s) { return deflateEnd(s); }
+static unsigned long zlib_deflateBound(z_stream *s, unsigned long sz) { return deflateBound(s, sz); }
+
+static int zlib_inflateInit(z_stream *s) { return inflateInit(s); }
+static int zlib_inflate(z_stream *s, int f) { return inflate(s, f); }
+static int zlib_inflateEnd(z_stream *s) { return inflateEnd(s); }
+
+
+/* link the stream to the compression library functions */
+static int register_engine(ext_stream *stream, int level)
+{
+ switch (level) {
+ case LZO_COMPRESSION:
+ die ("LZO compression still not implemented");
+ break;
+ default: /* assumed to be zlib */
+ stream->deflateInit_fn = zlib_deflateInit;
+ stream->deflate_fn = zlib_deflate;
+ stream->deflateEnd_fn = zlib_deflateEnd;
+ stream->deflateBound_fn = zlib_deflateBound;
+ stream->inflateInit_fn = zlib_inflateInit;
+ stream->inflate_fn = zlib_inflate;
+ stream->inflateEnd_fn = zlib_inflateEnd;
+ break;
+ };
+ return Z_OK;
+}
+
/*
* Compression helpers
*/
@@ -8,8 +43,9 @@
unsigned long compress_alloc(ext_stream *stream, int level, unsigned long size)
{
memset(stream, 0, sizeof(*stream));
- deflateInit(&stream->z, level);
- return deflateBound(&stream->z, size);
+ register_engine(stream, level);
+ stream->deflateInit_fn(&stream->z, level);
+ return stream->deflateBound_fn(&stream->z, size);
}
int compress_start(ext_stream *stream,
@@ -28,7 +64,7 @@ int compress_next(ext_stream *stream, int flush)
int result;
do {
- result = deflate(&stream->z, flush);
+ result = stream->deflate_fn(&stream->z, flush);
} while (result == Z_OK);
return result;
@@ -36,7 +72,7 @@ int compress_next(ext_stream *stream, int flush)
unsigned long compress_free(ext_stream *stream)
{
- deflateEnd(&stream->z);
+ stream->deflateEnd_fn(&stream->z);
return stream->z.total_out;
}
@@ -68,7 +104,8 @@ unsigned long compress_all(int level, unsigned char *in,
int decompress_alloc(ext_stream *stream)
{
memset(stream, 0, sizeof(*stream));
- return inflateInit(&stream->z);
+ register_engine(stream, Z_DEFAULT_COMPRESSION); // FIXME for now zlib assumed
+ return stream->inflateInit_fn(&stream->z);
}
int decompress_from(ext_stream *stream, unsigned char *in, unsigned long in_size)
@@ -87,24 +124,24 @@ int decompress_into(ext_stream *stream, unsigned char *out, unsigned long out_si
int decompress_next(ext_stream *stream, int flush)
{
- return inflate(&stream->z, flush);
+ return stream->inflate_fn(&stream->z, flush);
}
int decompress_next_from(ext_stream *stream, unsigned char *in, unsigned long in_size, int flush)
{
decompress_from(stream, in, in_size);
- return inflate(&stream->z, flush);
+ return stream->inflate_fn(&stream->z, flush);
}
int decompress_next_into(ext_stream *stream, unsigned char *out, unsigned long out_size, int flush)
{
decompress_into(stream, out, out_size);
- return inflate(&stream->z, flush);
+ return stream->inflate_fn(&stream->z, flush);
}
unsigned long decompress_free(ext_stream *stream)
{
- inflateEnd(&stream->z);
+ stream->inflateEnd_fn(&stream->z);
return stream->z.total_out;
}
diff --git a/compress.h b/compress.h
index d1de31f..151234a 100644
--- a/compress.h
+++ b/compress.h
@@ -1,6 +1,12 @@
#ifndef COMPRESS_H
#define COMPRESS_H
+/* Add here custom compression levels. First 0-9
+ * and -1 are reserved values used by zlib
+ */
+#define LZO_COMPRESSION 99
+
+
/* Any compress/decompress engine must implement all the
* below functions that are modeled after the zlib ones.
*/
--
1.5.4.rc2.98.g58cd2
-
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