src/util/u_vector.c

   1 /*
   2  * Copyright © 2015 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  */
  23 #include "util/u_vector.h"
  24
  25 int
  26 u_vector_init(struct u_vector *vector, uint32_t element_size, uint32_t size)
  27 {
  28    assert(util_is_power_of_two(size));
  29    assert(element_size < size && util_is_power_of_two(element_size));
  30
  31    vector->head = 0;
  32    vector->tail = 0;
  33    vector->element_size = element_size;
  34    vector->size = size;
  35    vector->data = malloc(size);
  36
  37    return vector->data != NULL;
  38 }
  39
  40 void *
  41 u_vector_add(struct u_vector *vector)
  42 {
  43    uint32_t offset, size, split, src_tail, dst_tail;
  44    void *data;
  45
  46    if (vector->head - vector->tail == vector->size) {
  47       size = vector->size * 2;
  48       data = malloc(size);
  49       if (data == NULL)
  50          return NULL;
  51       src_tail = vector->tail & (vector->size - 1);
  52       dst_tail = vector->tail & (size - 1);
  53       if (src_tail == 0) {
  54          /* Since we know that the vector is full, this means that it's
  55           * linear from start to end so we can do one copy.
  56           */
  57          memcpy((char *)data + dst_tail, vector->data, vector->size);
  58       } else {
  59          /* In this case, the vector is split into two pieces and we have
  60           * to do two copies.  We have to be careful to make sure each
  61           * piece goes to the right locations.  Thanks to the change in
  62           * size, it may or may not still wrap around.
  63           */
  64          split = u_align_u32(vector->tail, vector->size);
  65          assert(vector->tail <= split && split < vector->head);
  66          memcpy((char *)data + dst_tail, (char *)vector->data + src_tail,
  67                 split - vector->tail);
  68          memcpy((char *)data + (split & (size - 1)), vector->data,
  69                 vector->head - split);
  70       }
  71       free(vector->data);
  72       vector->data = data;
  73       vector->size = size;
  74    }
  75
  76    assert(vector->head - vector->tail < vector->size);
  77
  78    offset = vector->head & (vector->size - 1);
  79    vector->head += vector->element_size;
  80
  81    return (char *)vector->data + offset;
  82 }
  83
  84 void *
  85 u_vector_remove(struct u_vector *vector)
  86 {
  87    uint32_t offset;
  88
  89    if (vector->head == vector->tail)
  90       return NULL;
  91
  92    assert(vector->head - vector->tail <= vector->size);
  93
  94    offset = vector->tail & (vector->size - 1);
  95    vector->tail += vector->element_size;
  96
  97    return (char *)vector->data + offset;
  98 }