test unpacking of PackBits()

src/packbits.c

@@ -0,0 +1,69 @@
+/* vim:expandtab:ts=2 sw=2:
+*/
+/*  Grafx2 - The Ultimate 256-color bitmap paint program
+
+    Copyright 2018-2019 Thomas Bernard
+    Copyright 2008 Yves Rizoud
+    Copyright 2007 Adrien Destugues
+    Copyright 1996-2001 Sunset Design (Guillaume Dorme & Karl Maritaud)
+
+    Grafx2 is free software; you can redistribute it and/or
+    modify it under the terms of the GNU General Public License
+    as published by the Free Software Foundation; version 2
+    of the License.
+
+    Grafx2 is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with Grafx2; if not, see <http://www.gnu.org/licenses/>
+*/
+
+///@file packbits.c
+/// Packbits compression as used in IFF etc.
+/// see http://fileformats.archiveteam.org/wiki/PackBits
+
+#include <stdio.h>
+#include <string.h>
+#include "struct.h"
+#include "gfx2log.h"
+#include "packbits.h"
+
+int PackBits_unpack_from_file(FILE * f, byte * dest, unsigned int count)
+{
+  unsigned int i = 0;
+  while (i < count)
+  {
+    byte cmd;
+    if (fread(&cmd, 1, 1, f) != 1)
+      return PACKBITS_UNPACK_READ_ERROR;
+    if (cmd > 128)
+    {
+      // cmd > 128 => repeat (257 - cmd) the next byte
+      byte v;
+      if (fread(&v, 1, 1, f) != 1)
+        return PACKBITS_UNPACK_READ_ERROR;
+      if (count < (i + 257 - cmd))
+        return PACKBITS_UNPACK_OVERFLOW_ERROR;
+      memset(dest + i, v, (257 - cmd));
+      i += (257 - cmd);
+    }
+    else if (cmd < 128)
+    {
+      // cmd < 128 => copy (cmd + 1) bytes
+      if (count < (i + cmd + 1))
+        return PACKBITS_UNPACK_OVERFLOW_ERROR;
+      if (fread(dest + i, 1, (cmd + 1), f) != (unsigned)(cmd + 1))
+        return PACKBITS_UNPACK_READ_ERROR;
+      i += (cmd + 1);
+    }
+    else
+    {
+      // 128 = NOP
+      GFX2_Log(GFX2_WARNING, "NOP in packbits stream\n");
+    }
+  }
+  return PACKBITS_UNPACK_OK;
+}