On 08/09/2017 06:41 PM, Nicolai Hähnle wrote:
On 08.08.2017 18:57, Samuel Pitoiset wrote:
Will be used for allocating bindless descriptor slots for
RadeonSI.

Signed-off-by: Samuel Pitoiset <samuel.pitoi...@gmail.com>
---
  src/gallium/auxiliary/Makefile.sources |   1 +
src/gallium/auxiliary/util/u_idalloc.h | 103 +++++++++++++++++++++++++++++++++
  2 files changed, 104 insertions(+)
  create mode 100644 src/gallium/auxiliary/util/u_idalloc.h

diff --git a/src/gallium/auxiliary/Makefile.sources b/src/gallium/auxiliary/Makefile.sources
index 9ae8e6c8ca..10101d45a4 100644
--- a/src/gallium/auxiliary/Makefile.sources
+++ b/src/gallium/auxiliary/Makefile.sources
@@ -253,6 +253,7 @@ C_SOURCES := \
      util/u_hash_table.h \
      util/u_helpers.c \
      util/u_helpers.h \
+    util/u_idalloc.h \
      util/u_index_modify.c \
      util/u_index_modify.h \
      util/u_inlines.h \
diff --git a/src/gallium/auxiliary/util/u_idalloc.h b/src/gallium/auxiliary/util/u_idalloc.h
new file mode 100644
index 0000000000..e98f47ccb1
--- /dev/null
+++ b/src/gallium/auxiliary/util/u_idalloc.h
@@ -0,0 +1,103 @@
+/**************************************************************************
+ *
+ * Copyright 2017 Valve Corporation
+ * All Rights Reserved.
+ *
+ * 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 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 AUTHORS AND/OR ITS 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.
+ *
+ **************************************************************************/
+
+#ifndef U_IDALLOC_H
+#define U_IDALLOC_H
+
+/* A simple allocator that allocates and release "numbers". */
+
+#include "util/u_memory.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct util_idalloc
+{
+   uint32_t *data;
+   unsigned num_elements;
+};
+
+static inline void
+util_idalloc_init(struct util_idalloc *buf)
+{
+   memset(buf, 0, sizeof(*buf));
+}
+
+static inline void
+util_idalloc_fini(struct util_idalloc *buf)
+{
+   if (buf->data)
+      free(buf->data);
+}
+
+static inline void
+util_idalloc_resize(struct util_idalloc *buf, unsigned new_num_elements)
+{
+   assert(!(new_num_elements % 32));

Just round up. That's cheap enough, and there's no reason to leak this implementation detail to the caller.

Yeah, that sounds better.



+
+   if (new_num_elements > buf->num_elements) {
+      unsigned i;
+
+      buf->data = realloc(buf->data,
+                          (new_num_elements / 32) * sizeof(*buf->data));
+
+      for (i = buf->num_elements / 32; i < new_num_elements / 32; i++)
+         buf->data[i] = 0;
+      buf->num_elements = new_num_elements;
+   }
+}
+
+static inline int32_t
+util_idalloc_get_next_free(struct util_idalloc *buf)

Call it get_first_free and use bit scan per word. (I wouldn't be surprised if GCC actually recognized and optimized that pattern in optimized builds, but still...). But see below as well.


+{
+   for (unsigned i = 0; i < buf->num_elements; i++) {
+      if (!(buf->data[i / 32] & (1 << (i % 32))))
+         return i;
+   }
+   return -1;
+}
+
+static inline void
+util_idalloc_lock(struct util_idalloc *buf, unsigned id)
+{
+   assert(id < buf->num_elements);
+   buf->data[id / 32] |= 1 << (id % 32);
+}
+
+static inline void
+util_idalloc_unlock(struct util_idalloc *buf, unsigned id)
+{
+   assert(id < buf->num_elements);
+   buf->data[id / 32] &= ~(1 << (id % 32));
+}

lock/unlock sounds a lot like mutexes/locks in the threading sense.

Is the get_next_free/lock/unlock interface really needed? Since this module calls itself an ID allocator, how about an interface

unsigned util_idalloc_alloc(struct util_idalloc *buf);
void util_idalloc_free(struct util_idalloc *buf, unsigned id);

instead?

This interface is simpler and should be enough for my needs.


If that's the interface, I'd honestly prefer a non-inline implementation as well.

Cheers,
Nicolai


+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* U_IDALLOC_H */



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