#include <limits.h>
#include "debug.h"
#include "lib.h"
-#include "malloc.h"
-
-typedef unsigned long elem_type;
+#include "threads/malloc.h"
+#ifdef FILESYS
+#include "filesys/file.h"
+#endif
+\f
+/* Number of bits in an element. */
#define ELEM_BITS (sizeof (elem_type) * CHAR_BIT)
-#define ELEM_IDX(BIT_IDX) ((BIT_IDX) / ELEM_BITS)
-#define BIT_MASK(BIT_IDX) ((elem_type) 1 << ((BIT_IDX) % ELEM_BITS))
+/* Returns the index of the element that contains the bit
+ numbered BIT_IDX. */
+static inline size_t
+elem_idx (size_t bit_idx)
+{
+ return bit_idx / ELEM_BITS;
+}
+
+/* Returns an elem_type where only the bit corresponding to
+ BIT_IDX is turned on. */
+static inline elem_type
+bit_mask (size_t bit_idx)
+{
+ return (elem_type) 1 << (bit_idx % ELEM_BITS);
+}
+
+/* Returns the number of elements required for B's bits. */
static inline size_t
elem_cnt (const struct bitmap *b)
{
return DIV_ROUND_UP (b->bit_cnt, ELEM_BITS);
}
+/* Returns the number of bytes required by B's elements. */
static inline size_t
byte_cnt (const struct bitmap *b)
{
return sizeof (elem_type) * elem_cnt (b);
}
-void
+/* Returns a bit mask in which the bits actually used in the last
+ element of B's bits are set to 1 and the rest are set to 0. */
+static inline elem_type
+last_mask (const struct bitmap *b)
+{
+ int last_bits = b->bit_cnt % ELEM_BITS;
+ return last_bits ? ((elem_type) 1 << last_bits) - 1 : (elem_type) -1;
+}
+\f
+/* Initializes B to be a bitmap of BIT_CNT bits.
+ Returns true if successfalse, false if memory allocation
+ failed. */
+bool
bitmap_init (struct bitmap *b, size_t bit_cnt)
{
b->bit_cnt = bit_cnt;
b->bits = malloc (byte_cnt (b));
if (b->bits == NULL && bit_cnt > 0)
- return NULL;
+ return false;
bitmap_set_all (b, false);
- return b;
-}
-
-size_t
-bitmap_storage_size (const struct bitmap *b)
-{
- return byte_cnt (b);
+ return true;
}
+/* Destroys bitmap B, freeing its storage. */
void
bitmap_destroy (struct bitmap *b)
{
free (b->bits);
}
+/* Returns the number of bits in B. */
size_t
bitmap_size (const struct bitmap *b)
{
return b->bit_cnt;
}
+/* Sets the bit numbered IDX in B to VALUE. */
void
bitmap_set (struct bitmap *b, size_t idx, bool value)
{
ASSERT (b != NULL);
ASSERT (idx < b->bit_cnt);
if (value)
- b->bits[ELEM_IDX (idx)] |= BIT_MASK (idx);
+ b->bits[elem_idx (idx)] |= bit_mask (idx);
else
- b->bits[ELEM_IDX (idx)] &= ~BIT_MASK (idx);
+ b->bits[elem_idx (idx)] &= ~bit_mask (idx);
}
+/* Sets all bits in B to VALUE. */
void
bitmap_set_all (struct bitmap *b, bool value)
{
size_t i;
- size_t leftover_bits;
ASSERT (b != NULL);
- for (i = 0; i < elem_cnt (b); i++)
- b->bits[i] = value ? (elem_type) -1 : 0;
-
- leftover_bits = b->bit_cnt % ELEM_BITS;
- if (leftover_bits != 0)
- b->bits[i - 1] = ((elem_type) 1 << leftover_bits) - 1;
+ if (b->bit_cnt > 0)
+ {
+ for (i = 0; i < elem_cnt (b); i++)
+ b->bits[i] = value ? (elem_type) -1 : 0;
+ b->bits[elem_cnt (b) - 1] &= last_mask (b);
+ }
}
+/* Sets the bit numbered IDX in B to true. */
void
bitmap_mark (struct bitmap *b, size_t idx)
{
bitmap_set (b, idx, true);
}
+/* Sets the bit numbered IDX in B to false. */
void
bitmap_reset (struct bitmap *b, size_t idx)
{
bitmap_set (b, idx, false);
}
+/* Toggles the bit numbered IDX in B;
+ that is, if it is true, makes it false,
+ and if it is false, makes it true. */
void
bitmap_flip (struct bitmap *b, size_t idx)
{
ASSERT (b != NULL);
ASSERT (idx < b->bit_cnt);
- b->bits[ELEM_IDX (idx)] ^= BIT_MASK (idx);
+ b->bits[elem_idx (idx)] ^= bit_mask (idx);
}
+/* Returns the value of the bit numbered IDX in B. */
bool
bitmap_test (const struct bitmap *b, size_t idx)
{
ASSERT (b != NULL);
ASSERT (idx < b->bit_cnt);
- return (b->bits[ELEM_IDX (idx)] & BIT_MASK (idx)) != 0;
+ return (b->bits[elem_idx (idx)] & bit_mask (idx)) != 0;
}
+/* Returns the smallest index of a bit set to VALUE in B.
+ If no bits in B are set to VALUE, returns BITMAP_ERROR. */
size_t
bitmap_scan (const struct bitmap *b, bool value)
{
- elem_type ignore;
+ elem_type ignore = value ? 0 : (elem_type) -1;
size_t idx;
ASSERT (b != NULL);
- ignore = value ? 0 : (elem_type) -1;
for (idx = 0; idx < elem_cnt (b); idx++)
{
elem_type e = b->bits[idx];
- if (e != (elem_type) -1)
+ if (e != ignore)
{
idx *= ELEM_BITS;
- while ((e & 1) == 1)
+ while ((e & 1) != value)
{
e >>= 1;
idx++;
}
- return idx;
+ return idx < b->bit_cnt ? idx : BITMAP_ERROR;
}
}
return BITMAP_ERROR;
}
+/* Finds the smallest index of a bit set to false in B,
+ sets it to true, and returns the index.
+ If no bits in B are set to false, changes no bits and
+ returns BITMAP_ERROR. */
size_t
bitmap_find_and_set (struct bitmap *b)
{
return idx;
}
+/* Finds the smallest index of a bit set to true in B,
+ sets it to false, and returns the index.
+ If no bits in B are set to true, changes no bits and
+ returns BITMAP_ERROR. */
size_t
bitmap_find_and_clear (struct bitmap *b)
{
return idx;
}
+/* Returns the number of bits in B set to true. */
size_t
bitmap_set_cnt (const struct bitmap *b)
{
return cnt;
}
+/* Returns true if any bits in B are set to true,
+ and false otherwise.*/
bool
bitmap_any (const struct bitmap *b)
{
return false;
}
+/* Returns the number of bits in B set to false. */
bool
bitmap_clear_cnt (const struct bitmap *b)
{
return b->bit_cnt - bitmap_set_cnt (b);
}
+/* Returns true if no bits in B are set to true,
+ and false otherwise.*/
bool
bitmap_none (const struct bitmap *b)
{
return !bitmap_any (b);
}
+/* Returns true if every bit in B is set to true,
+ and false otherwise. */
bool
bitmap_all (const struct bitmap *b)
{
- size_t leftover_bits;
size_t i;
ASSERT (b != NULL);
for (i = 0; i < elem_cnt (b) - 1; i++)
if (b->bits[i] != (elem_type) -1)
- return true;
+ return false;
+ return b->bits[i] == last_mask (b);
+}
- leftover_bits = b->bit_cnt % ELEM_BITS;
- if (leftover_bits == 0)
- return b->bits[i] == (elem_type) -1;
- else
- return b->bits[i] == ((elem_type) 1 << leftover_bits) - 1;
+#ifdef FILESYS
+/* Returns the number of bytes needed to store B in a file. */
+size_t
+bitmap_file_size (const struct bitmap *b)
+{
+ return byte_cnt (b);
+}
+
+/* Reads FILE into B, ignoring errors. */
+void
+bitmap_read (struct bitmap *b, struct file *file)
+{
+ if (b->bit_cnt > 0)
+ {
+ file_read_at (file, b->bits, byte_cnt (b), 0);
+ b->bits[elem_cnt (b) - 1] &= last_mask (b);
+ }
+}
+
+/* Writes FILE to B, ignoring errors. */
+void
+bitmap_write (const struct bitmap *b, struct file *file)
+{
+ file_write_at (file, b->bits, byte_cnt (b), 0);
+}
+#endif /* FILESYS */
+
+/* Dumps the contents of B to the console as hexadecimal. */
+void
+bitmap_dump (const struct bitmap *b)
+{
+ hex_dump (b->bits, byte_cnt (b), false);
}
projects / pintos-anon / blobdiff