auto import from //depot/cupcake/@137055

linker/ba.c

@@ -0,0 +1,180 @@
+/*
+ * 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);
+}