X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/6e683a79101025ee0d371f0b9bece811856edd8d..d04c0e00da3a27693bbf9cc4f2d5c88e56d80f20:/utils/macros.h

diff --git a/utils/macros.h b/utils/macros.h
index dba22a7..2ca5a06 100644
--- a/utils/macros.h
+++ b/utils/macros.h
@@ -61,16 +61,18 @@
 #define MLIB__STR(x) #x
 #define STR(x) MLIB__STR(x)
 
-/* --- @GLUE@ --- *
+/* --- @GLUE@, @GLUE3@ --- *
  *
  * Arguments:	@x, y@ = two sequences of tokens
+ *		@z@ = a third sequence of tokens
  *
  * Returns:	A single token formed by gluing together the macro-expansions
- *		of @x@ and @y@.
+ *		of @x@ and @y@, and @z@ for @GLUE3@.
  */
 
 #define MLIB__GLUE(x, y) x##y
 #define GLUE(x, y) MLIB__GLUE(x, y)
+#define GLUE3(x, y, z) GLUE(x, MLIB__GLUE(y, z))
 
 /* --- @STATIC_ASSERT@ --- *
  *
@@ -87,9 +89,72 @@
 #  define STATIC_ASSERT(cond, msg) static_assert(!!(cond), msg)
 #else
 #  define STATIC_ASSERT(cond, msg)					\
-	IGNORABLE extern char static_assert_failed[2*!!(cond) - 1]
+	IGNORABLE extern char static_assert_failed[1 - 2*!(cond)]
 #endif
 
+/* --- @CHECK_TYPE@ ---
+ *
+ * Arguments:	@expty@ = expected type of @x@
+ *		@expty x@ = some object
+ *
+ * Returns:	Integer zero.
+ *
+ * Use:		Cause a compile-time failure unless the type of @x@ is
+ *		assignment-compatible with @expty@.
+ */
+
+#define CHECK_TYPE(expty, x) (!sizeof(*(expty *)0 = (x)))
+
+/* --- @CONVERT_CAREFULLY@ ---
+ *
+ * Arguments:	@newty@ = new type for the result
+ *		@expty@ = expected type of @x@
+ *		@expty x@ = some object
+ *
+ * Returns:	@x@, but coerced to type @newty@.
+ *
+ * Use:		Like @(newty)x@, except that it checks at compile-time that
+ *		@x@ is at least assignment-compatible with type @expty@
+ *		before trying.
+ */
+
+#define CONVERT_CAREFULLY(newty, expty, x)				\
+	(CHECK_TYPE(expty, x) + (/*unconst unvolatile*/ newty)(x))
+
+/* --- @UNCONST@, @UNVOLATILE@, @UNQUALIFY@ --- *
+ *
+ * Arguments:	@type@ = a type name
+ *		@type *p@ = a pointer
+ *
+ * Returns:	@p@, but without @const@, @volatile@ or both qualifiers.
+ *
+ * Use:		Strips qualifiers from pointer types.
+ *
+ *		The @UNCONST@ macro strips @const@.  It checks that @p@
+ *		has type `pointer to @type@ or @const type@'; if not, a
+ *		compile-time error results.  Otherwise, it returns the value
+ *		of @p@, converted to `pointer to (non-constant) @type@'.  It
+ *		will not silently strip a @volatile@ qualifier.
+ *
+ *		The @UNVOLATILE@ macro is similar, except that it strips
+ *		@volatile@ instead of @const@.  The @UNQUALIFY@ macro strips
+ *		both qualifiers.
+ */
+
+#define UNCONST(type, p) CONVERT_CAREFULLY(type *, const type *, p)
+#define UNVOLATILE(type, p) CONVERT_CAREFULLY(type *, volatile type *, p)
+#define UNQUALIFY(type, p)						\
+	CONVERT_CAREFULLY(type *, const volatile type *, p)
+
+/* --- @EMPTY@ --- *
+ *
+ * Arguments:	---
+ *
+ * Returns:	The empty token sequence.
+ */
+
+#define EMPTY
+
 /* --- @COMMA@ --- *
  *
  * Arguments:	---
@@ -197,7 +262,11 @@
 #if GCC_VERSION_P(2, 7) || CLANG_VERSION_P(0, 0)
 #  define LAUNDER(x)							\
 	({ __typeof__(x) _y; __asm__("" : "=g"(_y) : "0"(x)); _y; })
-#  define RELAX do __asm__ __volatile__("" ::: "memory"); while (0)
+#  define ADMIRE(x)							\
+	({ __asm__("" :: "g"(x)); })
+#  define ADMIRE_BUF(p, sz)						\
+	({ __asm__("" :: "m"(*(unsigned char *)p), "g"(sz) : "memory"); })
+#  define RELAX do __asm__(""); while (0)
 #endif
 
 #if CLANG_VERSION_P(3, 3)
@@ -318,6 +387,24 @@
 #  define LAUNDER(x) (x)
 #endif
 
+/* --- @ADMIRE@, @ADMIRE_BUF@ --- *
+ *
+ * Arguments:	@x@ = some scalar expression
+ *		@const void *p@, @size_t sz@ = a pointer and length
+ *
+ * Returns:	---
+ *
+ * Use:		Ensures that the compiler generates code to compute @x@ or
+ *		the contents of the buffer at @p@.
+ */
+
+#ifndef ADMIRE
+#  define ADMIRE(x) ((void)(x))
+#endif
+#ifndef ADMIRE_BUF
+#  define ADMIRE_BUF(p, sz) ((void)(p), (void)(sz))
+#endif
+
 /* --- @RELAX@ --- *
  *
  * Arguments:	---