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authorDavid Decotigny <decot@googlers.com>2016-02-19 09:23:59 -0500
committerDavid S. Miller <davem@davemloft.net>2016-02-19 22:54:09 -0500
commite52bc7c28ac9f54db6f86b19ed65c599def18c98 (patch)
tree91021921dbea2353d4aba01cf2546041184afd2f /lib/bitmap.c
parent76d13b568776fdef646c70878de406c90aef46a9 (diff)
downloadlinux-e52bc7c28ac9f54db6f86b19ed65c599def18c98.tar.bz2
lib/bitmap.c: conversion routines to/from u32 array
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@googlers.com> Reviewed-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'lib/bitmap.c')
-rw-r--r--lib/bitmap.c89
1 files changed, 89 insertions, 0 deletions
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 814814397cce..c66da508cbf7 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