1 files changed, 117 insertions, 0 deletions
diff --git a/src/zopfli/gzip_container.c b/src/zopfli/gzip_container.c
new file mode 100644
index 0000000..8a062f2
--- /dev/null
+++ b/src/zopfli/gzip_container.c
@@ -0,0 +1,117 @@
+/*
+Copyright 2013 Google Inc. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+Author: lode.vandevenne@gmail.com (Lode Vandevenne)
+Author: jyrki.alakuijala@gmail.com (Jyrki Alakuijala)
+*/
+
+#include "gzip_container.h"
+#include "util.h"
+
+#include <stdio.h>
+
+#include "deflate.h"
+
+/* Table of CRCs of all 8-bit messages. */
+static unsigned long crc_table[256];
+
+/* Flag: has the table been computed? Initially false. */
+static int crc_table_computed = 0;
+
+/* Makes the table for a fast CRC. */
+static void MakeCRCTable() {
+  unsigned long c;
+  int n, k;
+  for (n = 0; n < 256; n++) {
+    c = (unsigned long) n;
+    for (k = 0; k < 8; k++) {
+      if (c & 1) {
+        c = 0xedb88320L ^ (c >> 1);
+      } else {
+        c = c >> 1;
+      }
+    }
+    crc_table[n] = c;
+  }
+  crc_table_computed = 1;
+}
+
+
+/*
+Updates a running crc with the bytes buf[0..len-1] and returns
+the updated crc. The crc should be initialized to zero.
+*/
+static unsigned long UpdateCRC(unsigned long crc,
+                               const unsigned char *buf, size_t len) {
+  unsigned long c = crc ^ 0xffffffffL;
+  unsigned n;
+
+  if (!crc_table_computed)
+    MakeCRCTable();
+  for (n = 0; n < len; n++) {
+    c = crc_table[(c ^ buf[n]) & 0xff] ^ (c >> 8);
+  }
+  return c ^ 0xffffffffL;
+}
+
+/* Returns the CRC of the bytes buf[0..len-1]. */
+static unsigned long CRC(const unsigned char* buf, int len) {
+  return UpdateCRC(0L, buf, len);
+}
+
+/*
+Compresses the data according to the gzip specification.
+*/
+void ZopfliGzipCompress(const ZopfliOptions* options,
+                        const unsigned char* in, size_t insize,
+                        unsigned char** out, size_t* outsize) {
+  unsigned long crcvalue = CRC(in, insize);
+  unsigned char bp = 0;
+
+  ZOPFLI_APPEND_DATA(31, out, outsize);  /* ID1 */
+  ZOPFLI_APPEND_DATA(139, out, outsize);  /* ID2 */
+  ZOPFLI_APPEND_DATA(8, out, outsize);  /* CM */
+  ZOPFLI_APPEND_DATA(0, out, outsize);  /* FLG */
+  /* MTIME */
+  ZOPFLI_APPEND_DATA(0, out, outsize);
+  ZOPFLI_APPEND_DATA(0, out, outsize);
+  ZOPFLI_APPEND_DATA(0, out, outsize);
+  ZOPFLI_APPEND_DATA(0, out, outsize);
+
+  ZOPFLI_APPEND_DATA(2, out, outsize);  /* XFL, 2 indicates best compression. */
+  ZOPFLI_APPEND_DATA(3, out, outsize);  /* OS follows Unix conventions. */
+
+  ZopfliDeflate(options, 2 /* Dynamic block */, 1,
+                in, insize, &bp, out, outsize);
+
+  /* CRC */
+  ZOPFLI_APPEND_DATA(crcvalue % 256, out, outsize);
+  ZOPFLI_APPEND_DATA((crcvalue >> 8) % 256, out, outsize);
+  ZOPFLI_APPEND_DATA((crcvalue >> 16) % 256, out, outsize);
+  ZOPFLI_APPEND_DATA((crcvalue >> 24) % 256, out, outsize);
+
+  /* ISIZE */
+  ZOPFLI_APPEND_DATA(insize % 256, out, outsize);
+  ZOPFLI_APPEND_DATA((insize >> 8) % 256, out, outsize);
+  ZOPFLI_APPEND_DATA((insize >> 16) % 256, out, outsize);
+  ZOPFLI_APPEND_DATA((insize >> 24) % 256, out, outsize);
+
+  if (options->verbose) {
+    fprintf(stderr,
+            "Original Size: %d, Gzip: %d, Compression: %f%% Removed\n",
+            (int)insize, (int)*outsize,
+            100.0 * (double)(insize - *outsize) / (double)insize);
+  }
+}