gallium/util: add helper code for 1D integer range

Reviewed-by: Brian Paul <brianp@vmware.com>
v2: cosmetic changes based on Brian's review

Tested-by: Andreas Boll <andreas.boll.dev@gmail.com>
NOTE: This is a candidate for the 9.1 branch. (the next patch depends on it)

diff --git a/src/gallium/auxiliary/util/u_range.h b/src/gallium/auxiliary/util/u_range.h
new file mode 100644 (file)
index 0000000..4b1d0d1
--- /dev/null
+++ b/src/gallium/auxiliary/util/u_range.h
@@ -0,0 +1,89 @@
+/*
+ * Copyright 2013 Marek Olšák <maraeo@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * on the rights to use, copy, modify, merge, publish, distribute, sub
+ * license, and/or sell copies of the Software, and to permit persons to whom
+ * the Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+ * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+ * USE OR OTHER DEALINGS IN THE SOFTWARE. */
+
+/**
+ * @file
+ * 1D integer range, capable of the union and intersection operations.
+ *
+ * It only maintains a single interval which is extended when the union is
+ * done. This implementation is partially thread-safe (readers are not
+ * protected by a lock).
+ *
+ * @author Marek Olšák
+ */
+
+#ifndef U_RANGE_H
+#define U_RANGE_H
+
+#include "os/os_thread.h"
+
+struct util_range {
+   unsigned start; /* inclusive */
+   unsigned end; /* exclusive */
+
+   /* for the range to be consistent with multiple contexts: */
+   pipe_mutex write_mutex;
+};
+
+
+static INLINE void
+util_range_set_empty(struct util_range *range)
+{
+   range->start = ~0;
+   range->end = 0;
+}
+
+/* This is like a union of two sets. */
+static INLINE void
+util_range_add(struct util_range *range, unsigned start, unsigned end)
+{
+   if (start < range->start || end > range->end) {
+      pipe_mutex_lock(range->write_mutex);
+      range->start = MIN2(start, range->start);
+      range->end = MAX2(end, range->end);
+      pipe_mutex_unlock(range->write_mutex);
+   }
+}
+
+static INLINE boolean
+util_ranges_intersect(struct util_range *range, unsigned start, unsigned end)
+{
+   return MAX2(start, range->start) < MIN2(end, range->end);
+}
+
+
+/* Init/deinit */
+
+static INLINE void
+util_range_init(struct util_range *range)
+{
+   pipe_mutex_init(range->write_mutex);
+   util_range_set_empty(range);
+}
+
+static INLINE void
+util_range_destroy(struct util_range *range)
+{
+   pipe_mutex_destroy(range->write_mutex);
+}
+
+#endif