Switch AMI NVAR parser to Kaitai

common/umemstream.h

@@ -0,0 +1,58 @@
+/* umemstream.h
+
+ Copyright (c) 2023, Nikolaj Schlej. All rights reserved.
+ This program and the accompanying materials
+ are licensed and made available under the terms and conditions of the BSD License
+ which accompanies this distribution.  The full text of the license may be found at
+ http://opensource.org/licenses/bsd-license.php
+
+ THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+ */
+
+#ifndef UMEMSTREAM_H
+#define UMEMSTREAM_H
+
+#include <sstream>
+
+// NOTE: this implementation is certainly not a valid replacement to std::stringstream
+// NOTE: because it only supports getting through the buffer once
+// NOTE: however, we already do it this way, so it's enough for practical purposes
+
+class umembuf : public std::streambuf {
+public:
+    umembuf(const char *p, size_t l) {
+        setg((char*)p, (char*)p, (char*)p + l);
+    }
+
+    pos_type seekoff(off_type off, std::ios_base::seekdir dir, std::ios_base::openmode which = std::ios_base::in) override
+    {
+        (void)which;
+        if (dir == std::ios_base::cur)
+            gbump((int)off);
+        else if (dir == std::ios_base::end)
+            setg(eback(), egptr() + off, egptr());
+        else if (dir == std::ios_base::beg)
+            setg(eback(), eback() + off, egptr());
+        return gptr() - eback();
+    }
+
+    pos_type seekpos(pos_type sp, std::ios_base::openmode which) override
+    {
+        return seekoff(sp - pos_type(off_type(0)), std::ios_base::beg, which);
+    }
+};
+
+class umemstream : public std::istream {
+public:
+  umemstream(const char *p, size_t l) : std::istream(&buffer_),
+    buffer_(p, l) {
+    rdbuf(&buffer_);
+  }
+
+private:
+  umembuf buffer_;
+};
+
+#endif // UMEMSTREAM_H