Add a helper macro to use the new gen-options packed format.

[dxcommon.git] / src / xtra.h

diff --git a/src/xtra.h b/src/xtra.h
new file mode 100644 (file)
index 0000000..4de8df5
--- /dev/null
+++ b/src/xtra.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright © 2023 Nick Bowler
+ *
+ * License WTFPL2: Do What The Fuck You Want To Public License, version 2.
+ * This is free software: you are free to do what the fuck you want to.
+ * There is NO WARRANTY, to the extent permitted by law.
+ */
+
+#ifndef DX_XTRA_H_
+#define DX_XTRA_H_
+
+#define XTRA_PASTE(a, b) a ## b
+#define XTRA_PASTE2(a, b) XTRA_PASTE(a, b)
+
+#define XTRA_ARRAYSIZE(a) (sizeof (a) / sizeof (a)[0])
+
+/*
+ * This macro may be used to simplify construction of a 'struct option'
+ * array from the packed format produced by gen-options.awk.
+ *
+ * Expanding this in a function will
+ *
+ *   (1) declare a constant array with static storage duration that
+ *       contains the packed representation, and
+ *   (2) declare an array of struct option of suitable length, with
+ *       the given name, and
+ *   (3) emit code to fill the struct option array from the packed
+ *       representation.
+ *
+ * The uint_leastXX_t typedefs must be in scope in order to use this macro.
+ */
+#define XTRA_PACKED_LOPTS(name) \
+       static const XTRA_PASTE2(uint_least, XTRA_PASTE2(LOPT_PACK_BITS2, _t)) \
+               name##_packed[] = { LOPTS_PACKED_INITIALIZER }; \
+       struct option name[XTRA_ARRAYSIZE(name##_packed) + 1] = {0}; \
+       do { \
+               unsigned i; \
+               for (i = 0; i < XTRA_ARRAYSIZE(name##_packed); i++) \
+                       LOPT_UNPACK(name[i], name##_packed[i]); \
+       } while (0)
+
+#endif