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/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "linker.h"
#include "linker_debug.h"
#include "ba.h"
#undef min
#define min(a,b) ((a)<(b)?(a):(b))
#define BA_IS_FREE(index) (!(ba->bitmap[index].allocated))
#define BA_ORDER(index) ba->bitmap[index].order
#define BA_BUDDY_INDEX(index) ((index) ^ (1 << BA_ORDER(index)))
#define BA_NEXT_INDEX(index) ((index) + (1 << BA_ORDER(index)))
#define BA_OFFSET(index) ((index) * ba->min_alloc)
#define BA_START_ADDR(index) (BA_OFFSET(index) + ba->base)
#define BA_LEN(index) ((1 << BA_ORDER(index)) * ba->min_alloc)
static unsigned long ba_order(struct ba *ba, unsigned long len);
void ba_init(struct ba *ba)
{
int i, index = 0;
unsigned long max_order = ba_order(ba, ba->size);
if (ba->max_order == 0 || ba->max_order > max_order)
ba->max_order = max_order;
for (i = sizeof(ba->num_entries) * 8 - 1; i >= 0; i--) {
if (ba->num_entries & 1<<i) {
BA_ORDER(index) = i;
index = BA_NEXT_INDEX(index);
}
}
}
int ba_free(struct ba *ba, int index)
{
int buddy, curr = index;
/* clean up the bitmap, merging any buddies */
ba->bitmap[curr].allocated = 0;
/* find a slots buddy Buddy# = Slot# ^ (1 << order)
* if the buddy is also free merge them
* repeat until the buddy is not free or end of the bitmap is reached
*/
do {
buddy = BA_BUDDY_INDEX(curr);
if (BA_IS_FREE(buddy) &&
BA_ORDER(buddy) == BA_ORDER(curr)) {
BA_ORDER(buddy)++;
BA_ORDER(curr)++;
curr = min(buddy, curr);
} else {
break;
}
} while (curr < ba->num_entries);
return 0;
}
static unsigned long ba_order(struct ba *ba, unsigned long len)
{
unsigned long i;
len = (len + ba->min_alloc - 1) / ba->min_alloc;
len--;
for (i = 0; i < sizeof(len)*8; i++)
if (len >> i == 0)
break;
return i;
}
int ba_allocate(struct ba *ba, unsigned long len)
{
int curr = 0;
int end = ba->num_entries;
int best_fit = -1;
unsigned long order = ba_order(ba, len);
if (order > ba->max_order)
return -1;
/* look through the bitmap:
* if you find a free slot of the correct order use it
* otherwise, use the best fit (smallest with size > order) slot
*/
while (curr < end) {
if (BA_IS_FREE(curr)) {
if (BA_ORDER(curr) == (unsigned char)order) {
/* set the not free bit and clear others */
best_fit = curr;
break;
}
if (BA_ORDER(curr) > (unsigned char)order &&
(best_fit < 0 ||
BA_ORDER(curr) < BA_ORDER(best_fit)))
best_fit = curr;
}
curr = BA_NEXT_INDEX(curr);
}
/* if best_fit < 0, there are no suitable slots,
* return an error
*/
if (best_fit < 0)
return -1;
/* now partition the best fit:
* split the slot into 2 buddies of order - 1
* repeat until the slot is of the correct order
*/
while (BA_ORDER(best_fit) > (unsigned char)order) {
int buddy;
BA_ORDER(best_fit) -= 1;
buddy = BA_BUDDY_INDEX(best_fit);
BA_ORDER(buddy) = BA_ORDER(best_fit);
}
ba->bitmap[best_fit].allocated = 1;
return best_fit;
}
unsigned long ba_start_addr(struct ba *ba, int index)
{
return BA_START_ADDR(index);
}
unsigned long ba_len(struct ba *ba, int index)
{
return BA_LEN(index);
}
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