97d5406aef
This adds a very minimal internal allocator api that lets us create a dynamically growable (grow only) stack. Underlying the allocator is the idea of "sub stacks" which are simply malloc()'d chunks of memory kept in a linked list. The stack itself maintains a pointer to the current sub-stack and a current sub-stack-offset. 99% of the time allocating from the stack is just a case of returning a pointer to the current sub-stack + sub-stack-offset and bumping the offset by the allocation size. If there isn't room in the current sub-stack then we walk through the list of free sub-stacks looking for one that's big enough for the allocation and if we reach the end of the list then we allocate a new sub-stack twice as big as the last (or twice as big as the requested allocation if that's bigger). Since it's a stack model there is no api to free allocations, just a function to rewind the stack to the beginning. We expect this to be useful in multiple places in Cogl as an extremely fast allocator in cases when we know we can scrap all the allocations after we're done figuring something out or as a building block for other allocators. For example the tessellator used for CoglPath allocates lots of tiny structures that can all be freed after tessellation. Reviewed-by: Neil Roberts <neil@linux.intel.com> (cherry picked from commit 6ee4a7a1b7f695bdfeb10ffa4112e776beea0a9d)
52 lines
1.3 KiB
C
52 lines
1.3 KiB
C
/*
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* Cogl
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*
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* An object oriented GL/GLES Abstraction/Utility Layer
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*
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* Copyright (C) 2011 Intel Corporation.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see <http://www.gnu.org/licenses/>.
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*
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*
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*/
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#if !defined(__COGL_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
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#error "Only <cogl/cogl.h> can be included directly."
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#endif
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#include <glib.h>
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#ifndef __COGL_MEMORY_STACK__
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#define __COGL_MEMORY_STACK__
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G_BEGIN_DECLS
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typedef struct _CoglMemoryStack CoglMemoryStack;
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CoglMemoryStack *
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_cogl_memory_stack_new (size_t initial_size_bytes);
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void *
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_cogl_memory_stack_alloc (CoglMemoryStack *stack, size_t bytes);
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void
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_cogl_memory_stack_rewind (CoglMemoryStack *stack);
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void
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_cogl_memory_stack_free (CoglMemoryStack *stack);
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G_END_DECLS
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#endif /* __COGL_MEMORY_STACK__ */
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