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      1 /**************************************************************************
      2  *
      3  * Copyright 2009 VMware, Inc.
      4  * Copyright 2012 Marek Olk <maraeo (at) gmail.com>
      5  * All Rights Reserved.
      6  *
      7  * Permission is hereby granted, free of charge, to any person obtaining a
      8  * copy of this software and associated documentation files (the
      9  * "Software"), to deal in the Software without restriction, including
     10  * without limitation the rights to use, copy, modify, merge, publish,
     11  * distribute, sub license, and/or sell copies of the Software, and to
     12  * permit persons to whom the Software is furnished to do so, subject to
     13  * the following conditions:
     14  *
     15  * The above copyright notice and this permission notice (including the
     16  * next paragraph) shall be included in all copies or substantial portions
     17  * of the Software.
     18  *
     19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
     20  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     21  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
     22  * IN NO EVENT SHALL THE AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR
     23  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
     24  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
     25  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     26  *
     27  **************************************************************************/
     28 
     29 /* A simple allocator that suballocates memory from a large buffer. */
     30 
     31 #include "pipe/p_defines.h"
     32 #include "util/u_inlines.h"
     33 #include "pipe/p_context.h"
     34 #include "util/u_memory.h"
     35 #include "util/u_math.h"
     36 
     37 #include "u_suballoc.h"
     38 
     39 
     40 struct u_suballocator {
     41    struct pipe_context *pipe;
     42 
     43    unsigned size;          /* Size of the whole buffer, in bytes. */
     44    unsigned bind;          /* Bitmask of PIPE_BIND_* flags. */
     45    enum pipe_resource_usage usage;
     46    boolean zero_buffer_memory; /* If the buffer contents should be zeroed. */
     47 
     48    struct pipe_resource *buffer;   /* The buffer we suballocate from. */
     49    unsigned offset; /* Aligned offset pointing at the first unused byte. */
     50 };
     51 
     52 
     53 /**
     54  * Create a suballocator.
     55  *
     56  * \p zero_buffer_memory determines whether the buffer contents should be
     57  * cleared to 0 after the allocation.
     58  */
     59 struct u_suballocator *
     60 u_suballocator_create(struct pipe_context *pipe, unsigned size, unsigned bind,
     61                       enum pipe_resource_usage usage,
     62 		      boolean zero_buffer_memory)
     63 {
     64    struct u_suballocator *allocator = CALLOC_STRUCT(u_suballocator);
     65    if (!allocator)
     66       return NULL;
     67 
     68    allocator->pipe = pipe;
     69    allocator->size = size;
     70    allocator->bind = bind;
     71    allocator->usage = usage;
     72    allocator->zero_buffer_memory = zero_buffer_memory;
     73    return allocator;
     74 }
     75 
     76 void
     77 u_suballocator_destroy(struct u_suballocator *allocator)
     78 {
     79    pipe_resource_reference(&allocator->buffer, NULL);
     80    FREE(allocator);
     81 }
     82 
     83 void
     84 u_suballocator_alloc(struct u_suballocator *allocator, unsigned size,
     85                      unsigned alignment, unsigned *out_offset,
     86                      struct pipe_resource **outbuf)
     87 {
     88    allocator->offset = align(allocator->offset, alignment);
     89 
     90    /* Don't allow allocations larger than the buffer size. */
     91    if (size > allocator->size)
     92       goto fail;
     93 
     94    /* Make sure we have enough space in the buffer. */
     95    if (!allocator->buffer ||
     96        allocator->offset + size > allocator->size) {
     97       /* Allocate a new buffer. */
     98       pipe_resource_reference(&allocator->buffer, NULL);
     99       allocator->offset = 0;
    100       allocator->buffer =
    101          pipe_buffer_create(allocator->pipe->screen, allocator->bind,
    102                             allocator->usage, allocator->size);
    103       if (!allocator->buffer)
    104          goto fail;
    105 
    106       /* Clear the memory if needed. */
    107       if (allocator->zero_buffer_memory) {
    108          struct pipe_transfer *transfer = NULL;
    109          void *ptr;
    110 
    111          ptr = pipe_buffer_map(allocator->pipe, allocator->buffer,
    112 			       PIPE_TRANSFER_WRITE, &transfer);
    113          memset(ptr, 0, allocator->size);
    114          pipe_buffer_unmap(allocator->pipe, transfer);
    115       }
    116    }
    117 
    118    assert(allocator->offset % alignment == 0);
    119    assert(allocator->offset < allocator->buffer->width0);
    120    assert(allocator->offset + size <= allocator->buffer->width0);
    121 
    122    /* Return the buffer. */
    123    *out_offset = allocator->offset;
    124    pipe_resource_reference(outbuf, allocator->buffer);
    125 
    126    allocator->offset += size;
    127    return;
    128 
    129 fail:
    130    pipe_resource_reference(outbuf, NULL);
    131 }
    132