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bitmap: add virBitmapLastSetBit for finding the last bit position of bitmap

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Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
This commit is contained in:
Chen Fan 2014-11-04 10:44:39 +08:00 committed by Martin Kletzander
parent 4480cd2837
commit d2460f85d3
4 changed files with 61 additions and 1 deletions
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1
src/libvirt_private.syms
View File

@ -1011,6 +1011,7 @@ virBitmapFree;
virBitmapGetBit;
virBitmapIsAllClear;
virBitmapIsAllSet;
virBitmapLastSetBit;
virBitmapNew;
virBitmapNewCopy;
virBitmapNewData;

45
src/util/virbitmap.c
View File

@ -650,6 +650,51 @@ virBitmapNextSetBit(virBitmapPtr bitmap, ssize_t pos)
return ffsl(bits) - 1 + nl * VIR_BITMAP_BITS_PER_UNIT;
}
/**
* virBitmapLastSetBit:
* @bitmap: the bitmap
*
* Search for the last set bit in bitmap @bitmap.
*
* Returns the position of the found bit, or -1 if no bit is set.
*/
ssize_t
virBitmapLastSetBit(virBitmapPtr bitmap)
{
ssize_t i;
int unusedBits;
ssize_t sz;
unsigned long bits;
unusedBits = bitmap->map_len * VIR_BITMAP_BITS_PER_UNIT - bitmap->max_bit;
sz = bitmap->map_len - 1;
if (unusedBits > 0) {
bits = bitmap->map[sz] & (VIR_BITMAP_BIT(VIR_BITMAP_BITS_PER_UNIT - unusedBits) - 1);
if (bits != 0)
goto found;
sz--;
}
for (; sz >= 0; sz--) {
bits = bitmap->map[sz];
if (bits != 0)
goto found;
}
if (bits == 0)
return -1;
found:
for (i = VIR_BITMAP_BITS_PER_UNIT - 1; i >= 0; i--) {
if (bits & 1UL << i)
return i + sz * VIR_BITMAP_BITS_PER_UNIT;
}
return -1;
}
/**
* virBitmapNextClearBit:
* @bitmap: the bitmap

3
src/util/virbitmap.h
View File

@ -105,6 +105,9 @@ bool virBitmapIsAllClear(virBitmapPtr bitmap)
ssize_t virBitmapNextSetBit(virBitmapPtr bitmap, ssize_t pos)
ATTRIBUTE_NONNULL(1);
ssize_t virBitmapLastSetBit(virBitmapPtr bitmap)
ATTRIBUTE_NONNULL(1);
ssize_t virBitmapNextClearBit(virBitmapPtr bitmap, ssize_t pos)
ATTRIBUTE_NONNULL(1);

13
tests/virbitmaptest.c
View File

@ -171,7 +171,7 @@ test3(const void *data ATTRIBUTE_UNUSED)
return ret;
}
/* test for virBitmapNextSetBit, virBitmapNextClearBit */
/* test for virBitmapNextSetBit, virBitmapLastSetBit, virBitmapNextClearBit */
static int
test4(const void *data ATTRIBUTE_UNUSED)
{
@ -200,6 +200,9 @@ test4(const void *data ATTRIBUTE_UNUSED)
if (virBitmapNextSetBit(bitmap, -1) != -1)
goto error;
if (virBitmapLastSetBit(bitmap) != -1)
goto error;
for (i = 0; i < size; i++) {
if (virBitmapNextClearBit(bitmap, i - 1) != i)
goto error;
@ -232,6 +235,11 @@ test4(const void *data ATTRIBUTE_UNUSED)
if (virBitmapNextSetBit(bitmap, i) != -1)
goto error;
j = sizeof(bitsPos)/sizeof(int) - 1;
if (virBitmapLastSetBit(bitmap) != bitsPos[j])
goto error;
j = 0;
i = -1;
@ -255,6 +263,9 @@ test4(const void *data ATTRIBUTE_UNUSED)
if (virBitmapNextSetBit(bitmap, i) != -1)
goto error;
if (virBitmapLastSetBit(bitmap) != size - 1)
goto error;
if (virBitmapNextClearBit(bitmap, -1) != -1)
goto error;