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/**************************************************************************
*
* Copyright 2017 Valve Corporation
* All Rights Reserved.
*
* 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, sub license, 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 NON-INFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS AND/OR ITS SUPPLIERS 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.
*
**************************************************************************/
/**
* @file
* A simple allocator that allocates and release "numbers".
*
* @author Samuel Pitoiset <samuel.pitoiset@gmail.com>
*/
#include "util/u_idalloc.h"
#include "util/u_math.h"
#include <stdlib.h>
static void
util_idalloc_resize(struct util_idalloc *buf, unsigned new_num_elements)
{
if (new_num_elements > buf->num_elements) {
buf->data = realloc(buf->data, new_num_elements * sizeof(*buf->data));
memset(&buf->data[buf->num_elements], 0,
(new_num_elements - buf->num_elements) * sizeof(*buf->data));
buf->num_elements = new_num_elements;
}
}
void
util_idalloc_init(struct util_idalloc *buf, unsigned initial_num_ids)
{
memset(buf, 0, sizeof(*buf));
assert(initial_num_ids);
util_idalloc_resize(buf, DIV_ROUND_UP(initial_num_ids, 32));
}
void
util_idalloc_fini(struct util_idalloc *buf)
{
if (buf->data)
free(buf->data);
}
unsigned
util_idalloc_alloc(struct util_idalloc *buf)
{
unsigned num_elements = buf->num_elements;
for (unsigned i = buf->lowest_free_idx; i < num_elements; i++) {
if (buf->data[i] == 0xffffffff)
continue;
unsigned bit = ffs(~buf->data[i]) - 1;
buf->data[i] |= 1u << bit;
buf->lowest_free_idx = i;
return i * 32 + bit;
}
/* No slots available, resize and return the first free. */
util_idalloc_resize(buf, MAX2(num_elements, 1) * 2);
buf->lowest_free_idx = num_elements;
buf->data[num_elements] |= 1;
return num_elements * 32;
}
static unsigned
find_free_block(struct util_idalloc *buf, unsigned start)
{
for (unsigned i = start; i < buf->num_elements; i++) {
if (!buf->data[i])
return i;
}
return buf->num_elements;
}
/* Allocate a range of consecutive IDs. Return the first ID. */
unsigned
util_idalloc_alloc_range(struct util_idalloc *buf, unsigned num)
{
if (num == 1)
return util_idalloc_alloc(buf);
unsigned num_alloc = DIV_ROUND_UP(num, 32);
unsigned num_elements = buf->num_elements;
unsigned base = find_free_block(buf, buf->lowest_free_idx);
while (1) {
unsigned i;
for (i = base;
i < num_elements && i - base < num_alloc && !buf->data[i]; i++);
if (i - base == num_alloc)
goto ret; /* found */
if (i == num_elements)
break; /* not found */
/* continue searching */
base = !buf->data[i] ? i : i + 1;
}
/* No slots available, allocate more. */
util_idalloc_resize(buf, num_elements * 2 + num_alloc);
ret:
/* Mark the bits as used. */
for (unsigned i = base; i < base + num_alloc - (num % 32 != 0); i++)
buf->data[i] = 0xffffffff;
if (num % 32 != 0)
buf->data[base + num_alloc - 1] |= BITFIELD_MASK(num % 32);
if (buf->lowest_free_idx == base)
buf->lowest_free_idx = base + num / 32;
/* Validate this algorithm. */
for (unsigned i = 0; i < num; i++)
assert(util_idalloc_exists(buf, base * 32 + i));
return base * 32;
}
void
util_idalloc_free(struct util_idalloc *buf, unsigned id)
{
assert(id / 32 < buf->num_elements);
unsigned idx = id / 32;
buf->lowest_free_idx = MIN2(idx, buf->lowest_free_idx);
buf->data[idx] &= ~(1 << (id % 32));
}
void
util_idalloc_reserve(struct util_idalloc *buf, unsigned id)
{
if (id / 32 >= buf->num_elements)
util_idalloc_resize(buf, (id / 32 + 1) * 2);
buf->data[id / 32] |= 1u << (id % 32);
}
void
util_idalloc_mt_init(struct util_idalloc_mt *buf,
unsigned initial_num_ids, bool skip_zero)
{
simple_mtx_init(&buf->mutex, mtx_plain);
util_idalloc_init(&buf->buf, initial_num_ids);
buf->skip_zero = skip_zero;
if (skip_zero) {
ASSERTED unsigned zero = util_idalloc_alloc(&buf->buf);
assert(zero == 0);
}
}
/* Callback for drivers using u_threaded_context (abbreviated as tc). */
void
util_idalloc_mt_init_tc(struct util_idalloc_mt *buf)
{
util_idalloc_mt_init(buf, 1 << 16, true);
}
void
util_idalloc_mt_fini(struct util_idalloc_mt *buf)
{
util_idalloc_fini(&buf->buf);
simple_mtx_destroy(&buf->mutex);
}
unsigned
util_idalloc_mt_alloc(struct util_idalloc_mt *buf)
{
simple_mtx_lock(&buf->mutex);
unsigned id = util_idalloc_alloc(&buf->buf);
simple_mtx_unlock(&buf->mutex);
return id;
}
void
util_idalloc_mt_free(struct util_idalloc_mt *buf, unsigned id)
{
if (id == 0 && buf->skip_zero)
return;
simple_mtx_lock(&buf->mutex);
util_idalloc_free(&buf->buf, id);
simple_mtx_unlock(&buf->mutex);
}
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