From: David Decotigny <decot@xxxxxxxxxxxx>
Aimed at transferring bitmaps to/from user-space in a 32/64-bit agnostic
way.
Tested:
unit tests (next patch) on qemu i386, x86_64, ppc, ppc64 BE and LE,
ARM.
Signed-off-by: David Decotigny <decot@xxxxxxxxxxxx>
---
include/linux/bitmap.h | 10 ++++++
lib/bitmap.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 99 insertions(+)
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 9653fdb..e9b0b9a 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -59,6 +59,8 @@
* bitmap_find_free_region(bitmap, bits, order) Find and allocate bit region
* bitmap_release_region(bitmap, pos, order) Free specified bit region
* bitmap_allocate_region(bitmap, pos, order) Allocate specified bit region
+ * bitmap_from_u32array(dst, nbits, buf, nwords) *dst = *buf (nwords 32b words)
+ * bitmap_to_u32array(buf, nwords, src, nbits) *buf = *dst (nwords 32b words)
*/
/*
@@ -163,6 +165,14 @@ extern void bitmap_fold(unsigned long *dst, const unsigned long *orig,
extern int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order);
extern void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order);
extern int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order);
+extern unsigned int bitmap_from_u32array(unsigned long *bitmap,
+ unsigned int nbits,
+ const u32 *buf,
+ unsigned int nwords);
+extern unsigned int bitmap_to_u32array(u32 *buf,
+ unsigned int nwords,
+ const unsigned long *bitmap,
+ unsigned int nbits);
#ifdef __BIG_ENDIAN
extern void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits);
#else
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 8148143..c66da50 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -12,6 +12,8 @@
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/bug.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
#include <asm/page.h>
#include <asm/uaccess.h>
@@ -1060,6 +1062,93 @@ int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
EXPORT_SYMBOL(bitmap_allocate_region);
/**
+ * bitmap_from_u32array - copy the contents of a u32 array of bits to bitmap
+ * @bitmap: array of unsigned longs, the destination bitmap, non NULL
+ * @nbits: number of bits in @bitmap
+ * @buf: array of u32 (in host byte order), the source bitmap, non NULL
+ * @nwords: number of u32 words in @buf
+ *
+ * copy min(nbits, 32*nwords) bits from @buf to @bitmap, remaining
+ * bits between nword and nbits in @bitmap (if any) are cleared. In
+ * last word of @bitmap, the bits beyond nbits (if any) are kept
+ * unchanged.
+ *
+ * Return the number of bits effectively copied.
+ */
+unsigned int
+bitmap_from_u32array(unsigned long *bitmap, unsigned int nbits,
+ const u32 *buf, unsigned int nwords)
+{
+ unsigned int dst_idx, src_idx;
+
+ for (src_idx = dst_idx = 0; dst_idx < BITS_TO_LONGS(nbits); ++dst_idx) {
+ unsigned long part = 0;
+
+ if (src_idx < nwords)
+ part = buf[src_idx++];
+
+#if BITS_PER_LONG == 64
+ if (src_idx < nwords)
+ part |= ((unsigned long) buf[src_idx++]) << 32;
+#endif
+
+ if (dst_idx < nbits/BITS_PER_LONG)
+ bitmap[dst_idx] = part;
+ else {
+ unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
+
+ bitmap[dst_idx] = (bitmap[dst_idx] & ~mask)
+ | (part & mask);
+ }
+ }
+
+ return min_t(unsigned int, nbits, 32*nwords);
+}
+EXPORT_SYMBOL(bitmap_from_u32array);
+
+/**
+ * bitmap_to_u32array - copy the contents of bitmap to a u32 array of bits
+ * @buf: array of u32 (in host byte order), the dest bitmap, non NULL
+ * @nwords: number of u32 words in @buf
+ * @bitmap: array of unsigned longs, the source bitmap, non NULL
+ * @nbits: number of bits in @bitmap
+ *
+ * copy min(nbits, 32*nwords) bits from @bitmap to @buf. Remaining
+ * bits after nbits in @buf (if any) are cleared.
+ *
+ * Return the number of bits effectively copied.
+ */
+unsigned int
+bitmap_to_u32array(u32 *buf, unsigned int nwords,
+ const unsigned long *bitmap, unsigned int nbits)
+{
+ unsigned int dst_idx = 0, src_idx = 0;
+
+ while (dst_idx < nwords) {
+ unsigned long part = 0;
+
+ if (src_idx < BITS_TO_LONGS(nbits)) {
+ part = bitmap[src_idx];
+ if (src_idx >= nbits/BITS_PER_LONG)
+ part &= BITMAP_LAST_WORD_MASK(nbits);
+ src_idx++;
+ }
+
+ buf[dst_idx++] = part & 0xffffffffUL;
+
+#if BITS_PER_LONG == 64
+ if (dst_idx < nwords) {
+ part >>= 32;
+ buf[dst_idx++] = part & 0xffffffffUL;
+ }
+#endif
+ }
+
+ return min_t(unsigned int, nbits, 32*nwords);
+}
+EXPORT_SYMBOL(bitmap_to_u32array);
+
+/**
* bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
* @dst: destination buffer
* @src: bitmap to copy
--
2.7.0.rc3.207.g0ac5344
