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+	      CROSS-PLATFORM PORTABILITY GUIDELINES FOR GALLIUM3D 
+
+
+= General Considerations =
+
+The state tracker and winsys driver support a rather limited number of
+platforms. However, the pipe drivers are meant to run in a wide number of
+platforms. Hence the pipe drivers, the auxiliary modules, and all public
+headers in general, should strictly follow these guidelines to ensure
+
+
+= Compiler Support =
+
+* Include the p_compiler.h.
+
+* Don't use the 'inline' keyword, use the INLINE macro in p_compiler.h instead.
+
+* Cast explicitly when converting to integer types of smaller sizes.
+
+* Cast explicitly when converting between float, double and integral types.
+
+* Don't use named struct initializers.
+
+* Don't use variable number of macro arguments. Use static inline functions
+instead.
+
+* Don't use C99 features.
+
+= Standard Library =
+
+* Avoid including standard library headers. Most standard library functions are
+not available in Windows Kernel Mode. Use the appropriate p_*.h include.
+
+== Memory Allocation ==
+
+* Use MALLOC, CALLOC, FREE instead of the malloc, calloc, free functions.
+
+* Use align_pointer() function defined in u_memory.h for aligning pointers
+ in a portable way.
+
+== Debugging ==
+
+* Use the functions/macros in p_debug.h.
+
+* Don't include assert.h, call abort, printf, etc.
+
+
+= Code Style =
+
+== Inherantice in C ==
+
+The main thing we do is mimic inheritance by structure containment.
+
+Here's a silly made-up example:
+
+/* base class */
+struct buffer
+{
+  int size;
+  void (*validate)(struct buffer *buf);
+};
+
+/* sub-class of bufffer */
+struct texture_buffer
+{
+  struct buffer base;  /* the base class, MUST COME FIRST! */
+  int format;
+  int width, height;
+};
+
+
+Then, we'll typically have cast-wrapper functions to convert base-class 
+pointers to sub-class pointers where needed:
+
+static inline struct vertex_buffer *vertex_buffer(struct buffer *buf)
+{
+  return (struct vertex_buffer *) buf;
+}
+
+
+To create/init a sub-classed object:
+
+struct buffer *create_texture_buffer(int w, int h, int format)
+{
+  struct texture_buffer *t = malloc(sizeof(*t));
+  t->format = format;
+  t->width = w;
+  t->height = h;
+  t->base.size = w * h;
+  t->base.validate = tex_validate;
+  return &t->base;
+}
+
+Example sub-class method:
+
+void tex_validate(struct buffer *buf)
+{
+  struct texture_buffer *tb = texture_buffer(buf);
+  assert(tb->format);
+  assert(tb->width);
+  assert(tb->height);
+}
+
+
+Note that we typically do not use typedefs to make "class names"; we use
+'struct whatever' everywhere.
+
+Gallium's pipe_context and the subclassed psb_context, etc are prime examples 
+of this.  There's also many examples in Mesa and the Mesa state tracker.