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 24#include <string.h> 25#include "util/u_math.h" 26#include "util/u_vector.h" 27 28/** @file u_vector.c 29 * 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 34 * wraparound. 35 */ 36 37/** 38 * initial_element_count and element_size must be power-of-two. 39 */ 40int 41u_vector_init_pow2(struct u_vector *vector, 42 uint32_t initial_element_count, 43 uint32_t element_size) 44{ 45 assert(util_is_power_of_two_nonzero(initial_element_count)); 46 assert(util_is_power_of_two_nonzero(element_size)); 47 48 vector->head = 0; 49 vector->tail = 0; 50 vector->element_size = element_size; 51 vector->size = element_size * initial_element_count; 52 vector->data = malloc(vector->size); 53 54 return vector->data != NULL; 55} 56 57void * 58u_vector_add(struct u_vector *vector) 59{ 60 uint32_t offset, size, split, src_tail, dst_tail; 61 void *data; 62 63 if (vector->head - vector->tail == vector->size) { 64 size = vector->size * 2; 65 data = malloc(size); 66 if (data == NULL) 67 return NULL; 68 src_tail = vector->tail & (vector->size - 1); 69 dst_tail = vector->tail & (size - 1); 70 if (src_tail == 0) { 71 /* Since we know that the vector is full, this means that it's 72 * linear from start to end so we can do one copy. 73 */ 74 memcpy((char *)data + dst_tail, vector->data, vector->size); 75 } else { 76 /* In this case, the vector is split into two pieces and we have 77 * to do two copies. We have to be careful to make sure each 78 * piece goes to the right locations. Thanks to the change in 79 * size, it may or may not still wrap around. 80 */ 81 split = u_align_u32(vector->tail, vector->size); 82 assert(vector->tail <= split && split < vector->head); 83 memcpy((char *)data + dst_tail, (char *)vector->data + src_tail, 84 split - vector->tail); 85 memcpy((char *)data + (split & (size - 1)), vector->data, 86 vector->head - split); 87 } 88 free(vector->data); 89 vector->data = data; 90 vector->size = size; 91 } 92 93 assert(vector->head - vector->tail < vector->size); 94 95 offset = vector->head & (vector->size - 1); 96 vector->head += vector->element_size; 97 98 return (char *)vector->data + offset; 99} 100 101void * 102u_vector_remove(struct u_vector *vector) 103{ 104 uint32_t offset; 105 106 if (vector->head == vector->tail) 107 return NULL; 108 109 assert(vector->head - vector->tail <= vector->size); 110 111 offset = vector->tail & (vector->size - 1); 112 vector->tail += vector->element_size; 113 114 return (char *)vector->data + offset; 115} 116