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/*
* Copyright © 2015 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include <string.h>
#include "util/u_math.h"
#include "util/u_vector.h"
/** @file u_vector.c
*
* A dynamically growable, circular buffer. Elements are added at head and
* removed from tail. head and tail are free-running uint32_t indices and we
* only compute the modulo with size when accessing the array. This way,
* number of bytes in the queue is always head - tail, even in case of
* wraparound.
*/
int
u_vector_init(struct u_vector *vector, uint32_t element_size, uint32_t size)
{
assert(util_is_power_of_two_or_zero(size));
assert(element_size < size && util_is_power_of_two_or_zero(element_size));
vector->head = 0;
vector->tail = 0;
vector->element_size = element_size;
vector->size = size;
vector->data = malloc(size);
return vector->data != NULL;
}
void *
u_vector_add(struct u_vector *vector)
{
uint32_t offset, size, split, src_tail, dst_tail;
void *data;
if (vector->head - vector->tail == vector->size) {
size = vector->size * 2;
data = malloc(size);
if (data == NULL)
return NULL;
src_tail = vector->tail & (vector->size - 1);
dst_tail = vector->tail & (size - 1);
if (src_tail == 0) {
/* Since we know that the vector is full, this means that it's
* linear from start to end so we can do one copy.
*/
memcpy((char *)data + dst_tail, vector->data, vector->size);
} else {
/* In this case, the vector is split into two pieces and we have
* to do two copies. We have to be careful to make sure each
* piece goes to the right locations. Thanks to the change in
* size, it may or may not still wrap around.
*/
split = u_align_u32(vector->tail, vector->size);
assert(vector->tail <= split && split < vector->head);
memcpy((char *)data + dst_tail, (char *)vector->data + src_tail,
split - vector->tail);
memcpy((char *)data + (split & (size - 1)), vector->data,
vector->head - split);
}
free(vector->data);
vector->data = data;
vector->size = size;
}
assert(vector->head - vector->tail < vector->size);
offset = vector->head & (vector->size - 1);
vector->head += vector->element_size;
return (char *)vector->data + offset;
}
void *
u_vector_remove(struct u_vector *vector)
{
uint32_t offset;
if (vector->head == vector->tail)
return NULL;
assert(vector->head - vector->tail <= vector->size);
offset = vector->tail & (vector->size - 1);
vector->tail += vector->element_size;
return (char *)vector->data + offset;
}
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