gallium/util: add a simple allocator for suballocating from a large buffer

Tested-by: Aaron Watry <[email protected]>
Reviewed-by: Alex Deucher <[email protected]>

1 files changed, 132 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/util/u_suballoc.c b/src/gallium/auxiliary/util/u_suballoc.c
new file mode 100644
index 00000000000..efa9a0c5e09
--- /dev/null
+++ b/src/gallium/auxiliary/util/u_suballoc.c
@@ -0,0 +1,132 @@
+/**************************************************************************
+ * 
+ * Copyright 2009 VMware, Inc.
+ * Copyright 2012 Marek Olšák <[email protected]>
+ * 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.
+ * 
+ **************************************************************************/
+
+/* A simple allocator that suballocates memory from a large buffer. */
+
+#include "pipe/p_defines.h"
+#include "util/u_inlines.h"
+#include "pipe/p_context.h"
+#include "util/u_memory.h"
+#include "util/u_math.h"
+
+#include "u_suballoc.h"
+
+
+struct u_suballocator {
+   struct pipe_context *pipe;
+
+   unsigned size;          /* Size of the whole buffer, in bytes. */
+   unsigned alignment;     /* Alignment of each sub-allocation. */
+   unsigned bind;          /* Bitmask of PIPE_BIND_* flags. */
+   unsigned usage;         /* One of PIPE_USAGE_* flags. */
+   boolean zero_buffer_memory; /* If the buffer contents should be zeroed. */
+
+   struct pipe_resource *buffer;   /* The buffer we suballocate from. */
+   unsigned offset; /* Aligned offset pointing at the first unused byte. */
+};
+
+
+/**
+ * Create a suballocator.
+ *
+ * \p zero_buffer_memory determines whether the buffer contents should be
+ * cleared to 0 after the allocation.
+ */
+struct u_suballocator *
+u_suballocator_create(struct pipe_context *pipe, unsigned size,
+                      unsigned alignment, unsigned bind, unsigned usage,
+		      boolean zero_buffer_memory)
+{
+   struct u_suballocator *allocator = CALLOC_STRUCT(u_suballocator);
+   if (!allocator)
+      return NULL;
+
+   allocator->pipe = pipe;
+   allocator->size = align(size, alignment);
+   allocator->alignment = alignment;
+   allocator->bind = bind;
+   allocator->usage = usage;
+   allocator->zero_buffer_memory = zero_buffer_memory;
+   return allocator;
+}
+
+void
+u_suballocator_destroy(struct u_suballocator *allocator)
+{
+   pipe_resource_reference(&allocator->buffer, NULL);
+   FREE(allocator);
+}
+
+void
+u_suballocator_alloc(struct u_suballocator *allocator, unsigned size,
+                     unsigned *out_offset, struct pipe_resource **outbuf)
+{
+   unsigned alloc_size = align(size, allocator->alignment);
+
+   /* Don't allow allocations larger than the buffer size. */
+   if (alloc_size > allocator->size)
+      goto fail;
+
+   /* Make sure we have enough space in the buffer. */
+   if (!allocator->buffer ||
+       allocator->offset + alloc_size > allocator->size) {
+      /* Allocate a new buffer. */
+      pipe_resource_reference(&allocator->buffer, NULL);
+      allocator->offset = 0;
+      allocator->buffer =
+         pipe_buffer_create(allocator->pipe->screen, allocator->bind,
+                            allocator->usage, allocator->size);
+      if (!allocator->buffer)
+         goto fail;
+
+      /* Clear the memory if needed. */
+      if (allocator->zero_buffer_memory) {
+         struct pipe_transfer *transfer = NULL;
+         void *ptr;
+
+         ptr = pipe_buffer_map(allocator->pipe, allocator->buffer,
+			       PIPE_TRANSFER_WRITE, &transfer);
+         memset(ptr, 0, allocator->size);
+         pipe_buffer_unmap(allocator->pipe, transfer);
+      }
+   }
+
+   assert(allocator->offset % allocator->alignment == 0);
+   assert(allocator->offset < allocator->buffer->width0);
+   assert(allocator->offset + alloc_size <= allocator->buffer->width0);
+
+   /* Return the buffer. */
+   *out_offset = allocator->offset;
+   pipe_resource_reference(outbuf, allocator->buffer);
+
+   allocator->offset += alloc_size;
+   return;
+
+fail:
+   pipe_resource_reference(outbuf, NULL);
+}