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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
u_vector_init(struct u_vector * vector,uint32_t element_size,uint32_t size)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 *
u_vector_add(struct u_vector * vector)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 *
u_vector_remove(struct u_vector * vector)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 }
99