[pixbuf] Add generic concept of a pixel buffer

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/pixbuf.h

@@ -0,0 +1,55 @@
+#ifndef _IPXE_PIXBUF_H
+#define _IPXE_PIXBUF_H
+
+/** @file
+ *
+ * Pixel buffer
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stddef.h>
+#include <ipxe/refcnt.h>
+#include <ipxe/uaccess.h>
+
+/** A pixel buffer */
+struct pixel_buffer {
+	/** Reference count */
+	struct refcnt refcnt;
+	/** Width */
+	unsigned int width;
+	/** Height */
+	unsigned int height;
+	/** 32-bit (8:8:8:8) xRGB pixel data, in host-endian order */
+	userptr_t data;
+	/** Total length */
+	size_t len;
+};
+
+/**
+ * Get reference to pixel buffer
+ *
+ * @v pixbuf		Pixel buffer
+ * @ret pixbuf		Pixel buffer
+ */
+static inline __attribute__ (( always_inline )) struct pixel_buffer *
+pixbuf_get ( struct pixel_buffer *pixbuf ) {
+	ref_get ( &pixbuf->refcnt );
+	return pixbuf;
+}
+
+/**
+ * Drop reference to pixel buffer
+ *
+ * @v pixbuf		Pixel buffer
+ */
+static inline __attribute__ (( always_inline )) void
+pixbuf_put ( struct pixel_buffer *pixbuf ) {
+	ref_put ( &pixbuf->refcnt );
+}
+
+extern struct pixel_buffer * alloc_pixbuf ( unsigned int width,
+					    unsigned int height );
+
+#endif /* _IPXE_PIXBUF_H */