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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/sparc/lib/bitext.c
Initial import
Diffstat (limited to 'arch/sparc/lib/bitext.c')
-rw-r--r--arch/sparc/lib/bitext.c127
1 files changed, 127 insertions, 0 deletions
diff --git a/arch/sparc/lib/bitext.c b/arch/sparc/lib/bitext.c
new file mode 100644
index 000000000..8ec4e9c02
--- /dev/null
+++ b/arch/sparc/lib/bitext.c
@@ -0,0 +1,127 @@
+/*
+ * bitext.c: kernel little helper (of bit shuffling variety).
+ *
+ * Copyright (C) 2002 Pete Zaitcev <zaitcev@yahoo.com>
+ *
+ * The algorithm to search a zero bit string is geared towards its application.
+ * We expect a couple of fixed sizes of requests, so a rotating counter, reset
+ * by align size, should provide fast enough search while maintaining low
+ * fragmentation.
+ */
+
+#include <linux/string.h>
+#include <linux/bitmap.h>
+
+#include <asm/bitext.h>
+
+/**
+ * bit_map_string_get - find and set a bit string in bit map.
+ * @t: the bit map.
+ * @len: requested string length
+ * @align: requested alignment
+ *
+ * Returns offset in the map or -1 if out of space.
+ *
+ * Not safe to call from an interrupt (uses spin_lock).
+ */
+int bit_map_string_get(struct bit_map *t, int len, int align)
+{
+ int offset, count; /* siamese twins */
+ int off_new;
+ int align1;
+ int i, color;
+
+ if (t->num_colors) {
+ /* align is overloaded to be the page color */
+ color = align;
+ align = t->num_colors;
+ } else {
+ color = 0;
+ if (align == 0)
+ align = 1;
+ }
+ align1 = align - 1;
+ if ((align & align1) != 0)
+ BUG();
+ if (align < 0 || align >= t->size)
+ BUG();
+ if (len <= 0 || len > t->size)
+ BUG();
+ color &= align1;
+
+ spin_lock(&t->lock);
+ if (len < t->last_size)
+ offset = t->first_free;
+ else
+ offset = t->last_off & ~align1;
+ count = 0;
+ for (;;) {
+ off_new = find_next_zero_bit(t->map, t->size, offset);
+ off_new = ((off_new + align1) & ~align1) + color;
+ count += off_new - offset;
+ offset = off_new;
+ if (offset >= t->size)
+ offset = 0;
+ if (count + len > t->size) {
+ spin_unlock(&t->lock);
+/* P3 */ printk(KERN_ERR
+ "bitmap out: size %d used %d off %d len %d align %d count %d\n",
+ t->size, t->used, offset, len, align, count);
+ return -1;
+ }
+
+ if (offset + len > t->size) {
+ count += t->size - offset;
+ offset = 0;
+ continue;
+ }
+
+ i = 0;
+ while (test_bit(offset + i, t->map) == 0) {
+ i++;
+ if (i == len) {
+ bitmap_set(t->map, offset, len);
+ if (offset == t->first_free)
+ t->first_free = find_next_zero_bit
+ (t->map, t->size,
+ t->first_free + len);
+ if ((t->last_off = offset + len) >= t->size)
+ t->last_off = 0;
+ t->used += len;
+ t->last_size = len;
+ spin_unlock(&t->lock);
+ return offset;
+ }
+ }
+ count += i + 1;
+ if ((offset += i + 1) >= t->size)
+ offset = 0;
+ }
+}
+
+void bit_map_clear(struct bit_map *t, int offset, int len)
+{
+ int i;
+
+ if (t->used < len)
+ BUG(); /* Much too late to do any good, but alas... */
+ spin_lock(&t->lock);
+ for (i = 0; i < len; i++) {
+ if (test_bit(offset + i, t->map) == 0)
+ BUG();
+ __clear_bit(offset + i, t->map);
+ }
+ if (offset < t->first_free)
+ t->first_free = offset;
+ t->used -= len;
+ spin_unlock(&t->lock);
+}
+
+void bit_map_init(struct bit_map *t, unsigned long *map, int size)
+{
+ bitmap_zero(map, size);
+ memset(t, 0, sizeof *t);
+ spin_lock_init(&t->lock);
+ t->map = map;
+ t->size = size;
+}