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/*
* Copyright © 2025 Valve 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 "ralloc.h"
#include "u_range_remap.h"
/* Binary search for the range that contains n */
static struct range_entry *
get_range_entry(unsigned n, const struct range_remap *r_remap)
{
if (!r_remap->sorted_array)
return NULL;
unsigned low = 0;
unsigned high = r_remap->sorted_array_length - 1;
unsigned mid = (low + high) / 2;
struct range_entry *mid_entry = &r_remap->sorted_array[mid];
while (low <= high) {
if (n < mid_entry->start) {
if (low == high || mid == low) {
/* No entry found for n */
return NULL;
}
high = mid - 1;
mid = (low + high) / 2;
/* Move backward to new_mid */
mid_entry = &r_remap->sorted_array[mid];
} else if (n > mid_entry->end) {
if (low == high || mid == high) {
/* No entry found for n */
return NULL;
}
low = mid + 1;
mid = (low + high) / 2;
/* Move forward to new_mid */
mid_entry = &r_remap->sorted_array[mid];
} else {
/* n is within the current range */
return mid_entry;
}
}
return NULL;
}
/* Insert a new range entry or if ptr is non-null update an existing entries
* pointer value if start and end match exactly. If the range overlaps an
* existing entry we return NULL or if start and end match an entry exactly
* but ptr is null we return the existing entry.
*/
struct range_entry *
util_range_insert_remap(unsigned start, unsigned end,
struct range_remap *r_remap, void *ptr)
{
struct list_head *r_list = &r_remap->r_list;
struct list_range_entry *lre = NULL;
if (list_is_empty(r_list)) {
lre = rzalloc(r_remap->list_mem_ctx, struct list_range_entry);
list_addtail(&lre->node, r_list);
goto insert_end;
}
/* Shortcut for consecutive location inserts */
struct list_range_entry *last_entry =
list_last_entry(r_list, struct list_range_entry, node);
if (last_entry->entry.end < start) {
lre = rzalloc(r_remap->list_mem_ctx, struct list_range_entry);
list_addtail(&lre->node, r_list);
goto insert_end;
}
unsigned low = 0;
unsigned high = list_length(r_list) - 1;
unsigned mid = (low + high) / 2;
struct list_range_entry *mid_entry =
list_first_entry(r_list, struct list_range_entry, node);
unsigned i = 0;
while (i < mid) {
mid_entry =
list_entry(mid_entry->node.next, struct list_range_entry, node);
i++;
}
while (low <= high) {
if (end < mid_entry->entry.start) {
if (low == high || mid == low) {
lre = rzalloc(r_remap->list_mem_ctx, struct list_range_entry);
list_addtail(&lre->node, &mid_entry->node); /* insert before mid */
goto insert_end;
}
high = mid - 1;
unsigned new_mid = (low + high) / 2;
while (mid > new_mid) {
mid_entry =
list_entry(mid_entry->node.prev, struct list_range_entry, node);
mid--;
}
} else if (start > mid_entry->entry.end) {
if (low == high || mid == high) {
lre = rzalloc(r_remap->list_mem_ctx, struct list_range_entry);
list_add(&lre->node, &mid_entry->node); /* insert after mid */
goto insert_end;
}
low = mid + 1;
unsigned new_mid = (low + high) / 2;
while (mid < new_mid) {
mid_entry =
list_entry(mid_entry->node.next, struct list_range_entry, node);
mid++;
}
} else if (mid_entry->entry.start == start && mid_entry->entry.end == end) {
if (!ptr)
return &mid_entry->entry;
lre = mid_entry;
goto insert_end;
} else {
/* Attempting to insert an entry that overlaps an existing range */
return NULL;
}
}
insert_end:
lre->entry.start = start;
lre->entry.end = end;
lre->entry.ptr = ptr;
return &lre->entry;
}
void
util_range_switch_to_sorted_array(struct range_remap *r_remap)
{
r_remap->sorted_array_length = list_length(&r_remap->r_list);
if (r_remap->sorted_array) {
ralloc_free(r_remap->sorted_array);
r_remap->sorted_array = NULL;
}
if (r_remap->sorted_array_length == 0)
return;
r_remap->sorted_array = rzalloc_array(r_remap, struct range_entry,
r_remap->sorted_array_length);
unsigned i = 0;
list_for_each_entry(struct list_range_entry, e, &r_remap->r_list, node) {
r_remap->sorted_array[i].start = e->entry.start;
r_remap->sorted_array[i].end = e->entry.end;
r_remap->sorted_array[i].ptr = e->entry.ptr;
i++;
}
/* Free linked list and reset head */
list_inithead(&r_remap->r_list);
ralloc_free(r_remap->list_mem_ctx);
r_remap->list_mem_ctx = ralloc_context(r_remap);
}
/* Return the range entry that maps to n or NULL if no match found. */
struct range_entry *
util_range_remap(unsigned n, const struct range_remap *r_remap)
{
return get_range_entry(n, r_remap);
}
struct range_remap *
util_create_range_remap()
{
struct range_remap *r = rzalloc(NULL, struct range_remap);
list_inithead(&r->r_list);
r->list_mem_ctx = ralloc_context(r);
return r;
}
/* Free previous list and create a new empty list */
struct range_remap *
util_reset_range_remap(struct range_remap *r_remap)
{
ralloc_free(r_remap);
return util_create_range_remap();
}
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