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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"
struct ba_bits {
unsigned allocated:1; /* 1 if allocated, 0 if free */
unsigned order:7; /* size of the region in ba space */
};
struct ba_info {
/* start address of the ba space */
unsigned long base;
/* total size of the ba space */
unsigned long size;
/* number of entries in the ba space */
int num_entries;
/* the bitmap for the region indicating which entries are allocated
* and which are free */
struct ba_bits *bitmap;
};
#undef min
#define min(a,b) ((a)<(b)?(a):(b))
#define BA_MIN_ALLOC LIBINC
#define BA_MAX_ORDER 128
#define BA_START LIBBASE
#define BA_SIZE (LIBLAST - LIBBASE)
#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 struct ba_bits ba_bitmap[BA_SIZE / BA_MIN_ALLOC];
static struct ba_info ba = {
.base = BA_START,
.size = BA_SIZE,
.bitmap = ba_bitmap,
.num_entries = sizeof(ba_bitmap)/sizeof(ba_bitmap[0]),
};
void ba_init(void)
{
int i, index = 0;
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(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(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(unsigned long len)
{
int curr = 0;
int end = ba.num_entries;
int best_fit = -1;
unsigned long order = ba_order(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(int index)
{
return BA_START_ADDR(index);
}
unsigned long ba_len(int index)
{
return BA_LEN(index);
}
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