[Qemu-devel] [PATCH v2 06/15] bitmap: Add bitmap_copy_with_{src|dst}_offset()

[Peter Xu <peterx@redhat.com>]

These helpers copy the source bitmap to destination bitmap with a
shift either on the src or dst bitmap.

Meanwhile, we never have bitmap tests but we should.

This patch also introduces the initial test cases for utils/bitmap.c
but it only tests the newly introduced functions.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/qemu/bitmap.h  |  9 +++++
 tests/Makefile.include |  2 ++
 tests/test-bitmap.c    | 81 ++++++++++++++++++++++++++++++++++++++++++
 util/bitmap.c          | 73 +++++++++++++++++++++++++++++++++++++
 4 files changed, 165 insertions(+)
 create mode 100644 tests/test-bitmap.c

diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h
index 5c313346b9..cdaa953371 100644
--- a/include/qemu/bitmap.h
+++ b/include/qemu/bitmap.h
@@ -41,6 +41,10 @@
  * bitmap_find_next_zero_area(buf, len, pos, n, mask)	Find bit free area
  * bitmap_to_le(dst, src, nbits)      Convert bitmap to little endian
  * bitmap_from_le(dst, src, nbits)    Convert bitmap from little endian
+ * bitmap_copy_with_src_offset(dst, src, offset, nbits)
+ *                                    *dst = *src (with an offset upon src)
+ * bitmap_copy_with_dst_offset(dst, src, offset, nbits)
+ *                                    *dst = *src (with an offset upon dst)
  */
 
 /*
@@ -271,4 +275,9 @@ void bitmap_to_le(unsigned long *dst, const unsigned long *src,
 void bitmap_from_le(unsigned long *dst, const unsigned long *src,
                     long nbits);
 
+void bitmap_copy_with_src_offset(unsigned long *dst, const unsigned long *src,
+                                 long offset, long nbits);
+void bitmap_copy_with_dst_offset(unsigned long *dst, const unsigned long *src,
+                                 long shift, long nbits);
+
 #endif /* BITMAP_H */
diff --git a/tests/Makefile.include b/tests/Makefile.include
index 1865f6b322..5e2d7dddff 100644
--- a/tests/Makefile.include
+++ b/tests/Makefile.include
@@ -64,6 +64,7 @@ check-unit-y += tests/test-opts-visitor$(EXESUF)
 check-unit-$(CONFIG_BLOCK) += tests/test-coroutine$(EXESUF)
 check-unit-y += tests/test-visitor-serialization$(EXESUF)
 check-unit-y += tests/test-iov$(EXESUF)
+check-unit-y += tests/test-bitmap$(EXESUF)
 check-unit-$(CONFIG_BLOCK) += tests/test-aio$(EXESUF)
 check-unit-$(CONFIG_BLOCK) += tests/test-aio-multithread$(EXESUF)
 check-unit-$(CONFIG_BLOCK) += tests/test-throttle$(EXESUF)
@@ -529,6 +530,7 @@ tests/test-image-locking$(EXESUF): tests/test-image-locking.o $(test-block-obj-y
 tests/test-thread-pool$(EXESUF): tests/test-thread-pool.o $(test-block-obj-y)
 tests/test-iov$(EXESUF): tests/test-iov.o $(test-util-obj-y)
 tests/test-hbitmap$(EXESUF): tests/test-hbitmap.o $(test-util-obj-y) $(test-crypto-obj-y)
+tests/test-bitmap$(EXESUF): tests/test-bitmap.o $(test-util-obj-y)
 tests/test-x86-cpuid$(EXESUF): tests/test-x86-cpuid.o
 tests/test-xbzrle$(EXESUF): tests/test-xbzrle.o migration/xbzrle.o migration/page_cache.o $(test-util-obj-y)
 tests/test-cutils$(EXESUF): tests/test-cutils.o util/cutils.o $(test-util-obj-y)
diff --git a/tests/test-bitmap.c b/tests/test-bitmap.c
new file mode 100644
index 0000000000..36b4c07bf2
--- /dev/null
+++ b/tests/test-bitmap.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Bitmap.c unit-tests.
+ *
+ * Copyright (C) 2019, Red Hat, Inc.
+ *
+ * Author: Peter Xu <peterx@redhat.com>
+ */
+
+#include <stdlib.h>
+#include "qemu/osdep.h"
+#include "qemu/bitmap.h"
+
+#define BMAP_SIZE  1024
+
+static void check_bitmap_copy_with_offset(void)
+{
+    int i;
+    unsigned long *bmap1, *bmap2, *bmap3, total;
+
+    bmap1 = bitmap_new(BMAP_SIZE);
+    bmap2 = bitmap_new(BMAP_SIZE);
+    bmap3 = bitmap_new(BMAP_SIZE);
+
+    *bmap1 = random();
+    *(bmap1 + 1) = random();
+    *(bmap1 + 2) = random();
+    *(bmap1 + 3) = random();
+    total = BITS_PER_LONG * 4;
+
+    /* Shift 115 bits into bmap2 */
+    bitmap_copy_with_dst_offset(bmap2, bmap1, 115, total);
+    /* Shift another 85 bits into bmap3 */
+    bitmap_copy_with_dst_offset(bmap3, bmap2, 85, total + 115);
+    /* Shift back 200 bits back */
+    bitmap_copy_with_src_offset(bmap2, bmap3, 200, total);
+
+    for (i = 0; i < 3; i++) {
+        g_assert(*(bmap1 + i) == *(bmap2 + i));
+    }
+
+    bitmap_clear(bmap1, 0, BMAP_SIZE);
+    /* Set bits in bmap1 are 100-245 */
+    bitmap_set(bmap1, 100, 145);
+
+    /* Set bits in bmap2 are 60-205 */
+    bitmap_copy_with_src_offset(bmap2, bmap1, 40, 250);
+    for (i = 0; i < 60; i++) {
+        g_assert(test_bit(i, bmap2) == 0);
+    }
+    for (i = 60; i < 205; i++) {
+        g_assert(test_bit(i, bmap2));
+    }
+    g_assert(test_bit(205, bmap2) == 0);
+
+    /* Set bits in bmap3 are 135-280 */
+    bitmap_copy_with_dst_offset(bmap3, bmap1, 35, 250);
+    for (i = 0; i < 135; i++) {
+        g_assert(test_bit(i, bmap3) == 0);
+    }
+    for (i = 135; i < 280; i++) {
+        g_assert(test_bit(i, bmap3));
+    }
+    g_assert(test_bit(280, bmap3) == 0);
+
+    g_free(bmap1);
+    g_free(bmap2);
+    g_free(bmap3);
+}
+
+int main(int argc, char **argv)
+{
+    g_test_init(&argc, &argv, NULL);
+
+    g_test_add_func("/bitmap/bitmap_copy_with_offset",
+                    check_bitmap_copy_with_offset);
+
+    g_test_run();
+
+    return 0;
+}
diff --git a/util/bitmap.c b/util/bitmap.c
index cb618c65a5..391a7bb744 100644
--- a/util/bitmap.c
+++ b/util/bitmap.c
@@ -402,3 +402,76 @@ void bitmap_to_le(unsigned long *dst, const unsigned long *src,
 {
     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,
+                                 long shift, long nbits)
+{
+    unsigned long left_mask, right_mask, last_mask;
+
+    assert(shift >= 0);
+    /* Proper shift src pointer to the first word to copy from */
+    src += BIT_WORD(shift);
+    shift %= BITS_PER_LONG;
+    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 = (1 << nbits) - 1;
+        *dst |= (*(src + 1) & last_mask) << (BITS_PER_LONG - shift);
+    } else if (nbits) {
+        last_mask = (1 << 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,
+                                 long shift, long nbits)
+{
+    unsigned long left_mask, right_mask, last_mask;
+
+    assert(shift >= 0);
+    /* Proper shift src pointer to the first word to copy from */
+    dst += BIT_WORD(shift);
+    shift %= BITS_PER_LONG;
+    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 = ((1 << nbits) - 1) << (BITS_PER_LONG - shift);
+        *(dst + 1) = (*src & last_mask) >> (BITS_PER_LONG - shift);
+    } else if (nbits) {
+        last_mask = (1 << nbits) - 1;
+        *dst |= (*src & last_mask) << shift;
+    }
+}
-- 
2.17.1