fuchsia / third_party / mesa / a748a57e636985e7a30db44be8b935beddb92560 / . / src / util / u_vector.c

/* | |

* 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. | |

*/ | |

/** | |

* initial_element_count and element_size must be power-of-two. | |

*/ | |

int | |

u_vector_init_pow2(struct u_vector *vector, | |

uint32_t initial_element_count, | |

uint32_t element_size) | |

{ | |

assert(util_is_power_of_two_nonzero(initial_element_count)); | |

assert(util_is_power_of_two_nonzero(element_size)); | |

vector->head = 0; | |

vector->tail = 0; | |

vector->element_size = element_size; | |

vector->size = element_size * initial_element_count; | |

vector->data = malloc(vector->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; | |

} |