minmax: New module, safe min and max macros

[ccan] / ccan / minmax / minmax.h

diff --git a/ccan/minmax/minmax.h b/ccan/minmax/minmax.h
new file mode 100644 (file)
index 0000000..d111d1b
--- /dev/null
+++ b/ccan/minmax/minmax.h
@@ -0,0 +1,65 @@
+/* CC0 (Public domain) - see LICENSE file for details */
+#ifndef CCAN_MINMAX_H
+#define CCAN_MINMAX_H
+
+#include "config.h"
+
+#include <ccan/build_assert/build_assert.h>
+
+#if !HAVE_STATEMENT_EXPR || !HAVE_TYPEOF
+/*
+ * Without these, there's no way to avoid unsafe double evaluation of
+ * the arguments
+ */
+#error Sorry, minmax module requires statement expressions and typeof
+#endif
+
+#if HAVE_BUILTIN_TYPES_COMPATIBLE_P
+#define MINMAX_ASSERT_COMPATIBLE(a, b) \
+       BUILD_ASSERT(__builtin_types_compatible_p(a, b))
+#else
+#define MINMAX_ASSERT_COMPATIBLE(a, b) \
+       do { } while (0)
+#endif
+
+#define min(a, b) \
+       ({ \
+               typeof(a) _a = (a); \
+               typeof(b) _b = (b); \
+               MINMAX_ASSERT_COMPATIBLE(typeof(_a), typeof(_b)); \
+               _a < _b ? _a : _b; \
+       })
+
+#define max(a, b) \
+       ({ \
+               typeof(a) _a = (a); \
+               typeof(b) _b = (b); \
+               MINMAX_ASSERT_COMPATIBLE(typeof(_a), typeof(_b)); \
+               _a > _b ? _a : _b; \
+       })
+
+#define clamp(v, f, c) (max(min((v), (c)), (f)))
+
+
+#define min_t(t, a, b) \
+       ({ \
+               t _ta = (a); \
+               t _tb = (b); \
+               min(_ta, _tb); \
+       })
+#define max_t(t, a, b) \
+       ({ \
+               t _ta = (a); \
+               t _tb = (b); \
+               max(_ta, _tb); \
+       })
+
+#define clamp_t(t, v, f, c) \
+       ({ \
+               t _tv = (v); \
+               t _tf = (f); \
+               t _tc = (c); \
+               clamp(_tv, _tf, _tc); \
+       })
+
+#endif /* CCAN_MINMAX_H */