qemu

bitmap.c (13870B)

---

 /*
  * Bitmap Module
  *
  * Stolen from linux/src/lib/bitmap.c
  *
  * Copyright (C) 2010 Corentin Chary
  *
  * This source code is licensed under the GNU General Public License,
  * Version 2.
  */
 
 #include "qemu/osdep.h"
 #include "qemu/bitops.h"
 #include "qemu/bitmap.h"
 #include "qemu/atomic.h"
 
 /*
  * bitmaps provide an array of bits, implemented using an
  * array of unsigned longs.  The number of valid bits in a
  * given bitmap does _not_ need to be an exact multiple of
  * BITS_PER_LONG.
  *
  * The possible unused bits in the last, partially used word
  * of a bitmap are 'don't care'.  The implementation makes
  * no particular effort to keep them zero.  It ensures that
  * their value will not affect the results of any operation.
  * The bitmap operations that return Boolean (bitmap_empty,
  * for example) or scalar (bitmap_weight, for example) results
  * carefully filter out these unused bits from impacting their
  * results.
  *
  * These operations actually hold to a slightly stronger rule:
  * if you don't input any bitmaps to these ops that have some
  * unused bits set, then they won't output any set unused bits
  * in output bitmaps.
  *
  * The byte ordering of bitmaps is more natural on little
  * endian architectures.
  */
 
 int slow_bitmap_empty(const unsigned long *bitmap, long bits)
 {
     long k, lim = bits/BITS_PER_LONG;
 
     for (k = 0; k < lim; ++k) {
         if (bitmap[k]) {
             return 0;
         }
     }
     if (bits % BITS_PER_LONG) {
         if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) {
             return 0;
         }
     }
 
     return 1;
 }
 
 int slow_bitmap_full(const unsigned long *bitmap, long bits)
 {
     long k, lim = bits/BITS_PER_LONG;
 
     for (k = 0; k < lim; ++k) {
         if (~bitmap[k]) {
             return 0;
         }
     }
 
     if (bits % BITS_PER_LONG) {
         if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) {
             return 0;
         }
     }
 
     return 1;
 }
 
 int slow_bitmap_equal(const unsigned long *bitmap1,
                       const unsigned long *bitmap2, long bits)
 {
     long k, lim = bits/BITS_PER_LONG;
 
     for (k = 0; k < lim; ++k) {
         if (bitmap1[k] != bitmap2[k]) {
             return 0;
         }
     }
 
     if (bits % BITS_PER_LONG) {
         if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) {
             return 0;
         }
     }
 
     return 1;
 }
 
 void slow_bitmap_complement(unsigned long *dst, const unsigned long *src,
                             long bits)
 {
     long k, lim = bits/BITS_PER_LONG;
 
     for (k = 0; k < lim; ++k) {
         dst[k] = ~src[k];
     }
 
     if (bits % BITS_PER_LONG) {
         dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
     }
 }
 
 int slow_bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
                     const unsigned long *bitmap2, long bits)
 {
     long k;
     long nr = BITS_TO_LONGS(bits);
     unsigned long result = 0;
 
     for (k = 0; k < nr; k++) {
         result |= (dst[k] = bitmap1[k] & bitmap2[k]);
     }
     return result != 0;
 }
 
 void slow_bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
                     const unsigned long *bitmap2, long bits)
 {
     long k;
     long nr = BITS_TO_LONGS(bits);
 
     for (k = 0; k < nr; k++) {
         dst[k] = bitmap1[k] | bitmap2[k];
     }
 }
 
 void slow_bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
                      const unsigned long *bitmap2, long bits)
 {
     long k;
     long nr = BITS_TO_LONGS(bits);
 
     for (k = 0; k < nr; k++) {
         dst[k] = bitmap1[k] ^ bitmap2[k];
     }
 }
 
 int slow_bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
                        const unsigned long *bitmap2, long bits)
 {
     long k;
     long nr = BITS_TO_LONGS(bits);
     unsigned long result = 0;
 
     for (k = 0; k < nr; k++) {
         result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
     }
     return result != 0;
 }
 
 void bitmap_set(unsigned long *map, long start, long nr)
 {
     unsigned long *p = map + BIT_WORD(start);
     const long size = start + nr;
     int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
     unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
 
     assert(start >= 0 && nr >= 0);
 
     while (nr - bits_to_set >= 0) {
         *p |= mask_to_set;
         nr -= bits_to_set;
         bits_to_set = BITS_PER_LONG;
         mask_to_set = ~0UL;
         p++;
     }
     if (nr) {
         mask_to_set &= BITMAP_LAST_WORD_MASK(size);
         *p |= mask_to_set;
     }
 }
 
 void bitmap_set_atomic(unsigned long *map, long start, long nr)
 {
     unsigned long *p = map + BIT_WORD(start);
     const long size = start + nr;
     int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
     unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
 
     assert(start >= 0 && nr >= 0);
 
     /* First word */
     if (nr - bits_to_set > 0) {
         qatomic_or(p, mask_to_set);
         nr -= bits_to_set;
         bits_to_set = BITS_PER_LONG;
         mask_to_set = ~0UL;
         p++;
     }
 
     /* Full words */
     if (bits_to_set == BITS_PER_LONG) {
         while (nr >= BITS_PER_LONG) {
             *p = ~0UL;
             nr -= BITS_PER_LONG;
             p++;
         }
     }
 
     /* Last word */
     if (nr) {
         mask_to_set &= BITMAP_LAST_WORD_MASK(size);
         qatomic_or(p, mask_to_set);
     } else {
         /* If we avoided the full barrier in qatomic_or(), issue a
          * barrier to account for the assignments in the while loop.
          */
         smp_mb();
     }
 }
 
 void bitmap_clear(unsigned long *map, long start, long nr)
 {
     unsigned long *p = map + BIT_WORD(start);
     const long size = start + nr;
     int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
     unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
 
     assert(start >= 0 && nr >= 0);
 
     while (nr - bits_to_clear >= 0) {
         *p &= ~mask_to_clear;
         nr -= bits_to_clear;
         bits_to_clear = BITS_PER_LONG;
         mask_to_clear = ~0UL;
         p++;
     }
     if (nr) {
         mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
         *p &= ~mask_to_clear;
     }
 }
 
 bool bitmap_test_and_clear(unsigned long *map, long start, long nr)
 {
     unsigned long *p = map + BIT_WORD(start);
     const long size = start + nr;
     int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
     unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
     bool dirty = false;
 
     assert(start >= 0 && nr >= 0);
 
     /* First word */
     if (nr - bits_to_clear > 0) {
         if ((*p) & mask_to_clear) {
             dirty = true;
         }
         *p &= ~mask_to_clear;
         nr -= bits_to_clear;
         bits_to_clear = BITS_PER_LONG;
         p++;
     }
 
     /* Full words */
     if (bits_to_clear == BITS_PER_LONG) {
         while (nr >= BITS_PER_LONG) {
             if (*p) {
                 dirty = true;
                 *p = 0;
             }
             nr -= BITS_PER_LONG;
             p++;
         }
     }
 
     /* Last word */
     if (nr) {
         mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
         if ((*p) & mask_to_clear) {
             dirty = true;
         }
         *p &= ~mask_to_clear;
     }
 
     return dirty;
 }
 
 bool bitmap_test_and_clear_atomic(unsigned long *map, long start, long nr)
 {
     unsigned long *p = map + BIT_WORD(start);
     const long size = start + nr;
     int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
     unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
     unsigned long dirty = 0;
     unsigned long old_bits;
 
     assert(start >= 0 && nr >= 0);
 
     /* First word */
     if (nr - bits_to_clear > 0) {
         old_bits = qatomic_fetch_and(p, ~mask_to_clear);
         dirty |= old_bits & mask_to_clear;
         nr -= bits_to_clear;
         bits_to_clear = BITS_PER_LONG;
         mask_to_clear = ~0UL;
         p++;
     }
 
     /* Full words */
     if (bits_to_clear == BITS_PER_LONG) {
         while (nr >= BITS_PER_LONG) {
             if (*p) {
                 old_bits = qatomic_xchg(p, 0);
                 dirty |= old_bits;
             }
             nr -= BITS_PER_LONG;
             p++;
         }
     }
 
     /* Last word */
     if (nr) {
         mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
         old_bits = qatomic_fetch_and(p, ~mask_to_clear);
         dirty |= old_bits & mask_to_clear;
     } else {
         if (!dirty) {
             smp_mb();
         }
     }
 
     return dirty != 0;
 }
 
 void bitmap_copy_and_clear_atomic(unsigned long *dst, unsigned long *src,
                                   long nr)
 {
     while (nr > 0) {
         *dst = qatomic_xchg(src, 0);
         dst++;
         src++;
         nr -= BITS_PER_LONG;
     }
 }
 
 #define ALIGN_MASK(x,mask)      (((x)+(mask))&~(mask))
 
 /**
  * bitmap_find_next_zero_area - find a contiguous aligned zero area
  * @map: The address to base the search on
  * @size: The bitmap size in bits
  * @start: The bitnumber to start searching at
  * @nr: The number of zeroed bits we're looking for
  * @align_mask: Alignment mask for zero area
  *
  * The @align_mask should be one less than a power of 2; the effect is that
  * the bit offset of all zero areas this function finds is multiples of that
  * power of 2. A @align_mask of 0 means no alignment is required.
  */
 unsigned long bitmap_find_next_zero_area(unsigned long *map,
                                          unsigned long size,
                                          unsigned long start,
                                          unsigned long nr,
                                          unsigned long align_mask)
 {
     unsigned long index, end, i;
 again:
     index = find_next_zero_bit(map, size, start);
 
     /* Align allocation */
     index = ALIGN_MASK(index, align_mask);
 
     end = index + nr;
     if (end > size) {
         return end;
     }
     i = find_next_bit(map, end, index);
     if (i < end) {
         start = i + 1;
         goto again;
     }
     return index;
 }
 
 int slow_bitmap_intersects(const unsigned long *bitmap1,
                            const unsigned long *bitmap2, long bits)
 {
     long k, lim = bits/BITS_PER_LONG;
 
     for (k = 0; k < lim; ++k) {
         if (bitmap1[k] & bitmap2[k]) {
             return 1;
         }
     }
 
     if (bits % BITS_PER_LONG) {
         if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) {
             return 1;
         }
     }
     return 0;
 }
 
 long slow_bitmap_count_one(const unsigned long *bitmap, long nbits)
 {
     long k, lim = nbits / BITS_PER_LONG, result = 0;
 
     for (k = 0; k < lim; k++) {
         result += ctpopl(bitmap[k]);
     }
 
     if (nbits % BITS_PER_LONG) {
         result += ctpopl(bitmap[k] & BITMAP_LAST_WORD_MASK(nbits));
     }
 
     return result;
 }
 
 static void bitmap_to_from_le(unsigned long *dst,
                               const unsigned long *src, long nbits)
 {
     long len = BITS_TO_LONGS(nbits);
 
 #if HOST_BIG_ENDIAN
     long index;
 
     for (index = 0; index < len; index++) {
 # if HOST_LONG_BITS == 64
         dst[index] = bswap64(src[index]);
 # else
         dst[index] = bswap32(src[index]);
 # endif
     }
 #else
     memcpy(dst, src, len * sizeof(unsigned long));
 #endif
 }
 
 void bitmap_from_le(unsigned long *dst, const unsigned long *src,
                     long nbits)
 {
     bitmap_to_from_le(dst, src, nbits);
 }
 
 void bitmap_to_le(unsigned long *dst, const unsigned long *src,
                   long nbits)
 {
     bitmap_to_from_le(dst, src, nbits);
 }
 
 /*
  * Copy "src" bitmap with a positive offset and put it into the "dst"
  * bitmap.  The caller needs to make sure the bitmap size of "src"
  * is bigger than (shift + nbits).
  */
 void bitmap_copy_with_src_offset(unsigned long *dst, const unsigned long *src,
                                  unsigned long shift, unsigned long nbits)
 {
     unsigned long left_mask, right_mask, last_mask;
 
     /* Proper shift src pointer to the first word to copy from */
     src += BIT_WORD(shift);
     shift %= BITS_PER_LONG;
 
     if (!shift) {
         /* Fast path */
         bitmap_copy(dst, src, nbits);
         return;
     }
 
     right_mask = (1ul << shift) - 1;
     left_mask = ~right_mask;
 
     while (nbits >= BITS_PER_LONG) {
         *dst = (*src & left_mask) >> shift;
         *dst |= (src[1] & right_mask) << (BITS_PER_LONG - shift);
         dst++;
         src++;
         nbits -= BITS_PER_LONG;
     }
 
     if (nbits > BITS_PER_LONG - shift) {
         *dst = (*src & left_mask) >> shift;
         nbits -= BITS_PER_LONG - shift;
         last_mask = (1ul << nbits) - 1;
         *dst |= (src[1] & last_mask) << (BITS_PER_LONG - shift);
     } else if (nbits) {
         last_mask = (1ul << nbits) - 1;
         *dst = (*src >> shift) & last_mask;
     }
 }
 
 /*
  * Copy "src" bitmap into the "dst" bitmap with an offset in the
  * "dst".  The caller needs to make sure the bitmap size of "dst" is
  * bigger than (shift + nbits).
  */
 void bitmap_copy_with_dst_offset(unsigned long *dst, const unsigned long *src,
                                  unsigned long shift, unsigned long nbits)
 {
     unsigned long left_mask, right_mask, last_mask;
 
     /* Proper shift dst pointer to the first word to copy from */
     dst += BIT_WORD(shift);
     shift %= BITS_PER_LONG;
 
     if (!shift) {
         /* Fast path */
         bitmap_copy(dst, src, nbits);
         return;
     }
 
     right_mask = (1ul << (BITS_PER_LONG - shift)) - 1;
     left_mask = ~right_mask;
 
     *dst &= (1ul << shift) - 1;
     while (nbits >= BITS_PER_LONG) {
         *dst |= (*src & right_mask) << shift;
         dst[1] = (*src & left_mask) >> (BITS_PER_LONG - shift);
         dst++;
         src++;
         nbits -= BITS_PER_LONG;
     }
 
     if (nbits > BITS_PER_LONG - shift) {
         *dst |= (*src & right_mask) << shift;
         nbits -= BITS_PER_LONG - shift;
         last_mask = ((1ul << nbits) - 1) << (BITS_PER_LONG - shift);
         dst[1] = (*src & last_mask) >> (BITS_PER_LONG - shift);
     } else if (nbits) {
         last_mask = (1ul << nbits) - 1;
         *dst |= (*src & last_mask) << shift;
     }
 }