2 * Copyright © 2015 Intel Corporation
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5 * copy of this software and associated documentation files (the "Software"),
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7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
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9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice (including the next
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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
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25 #include "util/u_math.h"
26 #include "util/u_vector.h"
30 * A dynamically growable, circular buffer. Elements are added at head and
31 * removed from tail. head and tail are free-running uint32_t indices and we
32 * only compute the modulo with size when accessing the array. This way,
33 * number of bytes in the queue is always head - tail, even in case of
38 u_vector_init(struct u_vector *vector, uint32_t element_size, uint32_t size)
40 assert(util_is_power_of_two_nonzero(size));
41 assert(element_size < size && util_is_power_of_two_nonzero(element_size));
45 vector->element_size = element_size;
47 vector->data = malloc(size);
49 return vector->data != NULL;
53 u_vector_add(struct u_vector *vector)
55 uint32_t offset, size, split, src_tail, dst_tail;
58 if (vector->head - vector->tail == vector->size) {
59 size = vector->size * 2;
63 src_tail = vector->tail & (vector->size - 1);
64 dst_tail = vector->tail & (size - 1);
66 /* Since we know that the vector is full, this means that it's
67 * linear from start to end so we can do one copy.
69 memcpy((char *)data + dst_tail, vector->data, vector->size);
71 /* In this case, the vector is split into two pieces and we have
72 * to do two copies. We have to be careful to make sure each
73 * piece goes to the right locations. Thanks to the change in
74 * size, it may or may not still wrap around.
76 split = u_align_u32(vector->tail, vector->size);
77 assert(vector->tail <= split && split < vector->head);
78 memcpy((char *)data + dst_tail, (char *)vector->data + src_tail,
79 split - vector->tail);
80 memcpy((char *)data + (split & (size - 1)), vector->data,
81 vector->head - split);
88 assert(vector->head - vector->tail < vector->size);
90 offset = vector->head & (vector->size - 1);
91 vector->head += vector->element_size;
93 return (char *)vector->data + offset;
97 u_vector_remove(struct u_vector *vector)
101 if (vector->head == vector->tail)
104 assert(vector->head - vector->tail <= vector->size);
106 offset = vector->tail & (vector->size - 1);
107 vector->tail += vector->element_size;
109 return (char *)vector->data + offset;