Subject: [PATCH net-next v7 01/19] lib/bitmap.c: conversion routines to/from u32 array

From: David Decotigny <[email-masked]>
Date: Sun, 7 Feb 2016 17:08:45 -0800

From: David Decotigny <decot-Ypc/8FJVVoBWk0Htik3J/[email-masked]>

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-Ypc/8FJVVoBWk0Htik3J/[email-masked]>
---
 include/linux/bitmap.h |  6 ++++
 lib/bitmap.c           | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 92 insertions(+)

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 9653fdb..f7dc158 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 +165,10 @@ 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 void bitmap_from_u32array(unsigned long *bitmap, unsigned int nbits,
+				 const u32 *buf, unsigned int nwords);
+extern void 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..e1cc648 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 +1062,90 @@ 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.
+ */
+void bitmap_from_u32array(unsigned long *bitmap, unsigned int nbits,
+			  const u32 *buf, unsigned int nwords)
+{
+	unsigned int k;
+	const u32 *src = buf;
+
+	for (k = 0; k < BITS_TO_LONGS(nbits); ++k) {
+		unsigned long part = 0;
+
+		if (nwords) {
+			part = *src++;
+			nwords--;
+		}
+
+#if BITS_PER_LONG == 64
+		if (nwords) {
+			part |= ((unsigned long) *src++) << 32;
+			nwords--;
+		}
+#endif
+
+		if (k < nbits/BITS_PER_LONG)
+			bitmap[k] = part;
+		else {
+			unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
+
+			bitmap[k] = (bitmap[k] & ~mask) | (part & mask);
+		}
+	}
+}
+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.
+ */
+void bitmap_to_u32array(u32 *buf, unsigned int nwords,
+			const unsigned long *bitmap, unsigned int nbits)
+{
+	unsigned int k = 0;
+	u32 *dst = buf;
+
+	while (nwords) {
+		unsigned long part = 0;
+
+		if (k < BITS_TO_LONGS(nbits)) {
+			part = bitmap[k];
+			if (k >= nbits/BITS_PER_LONG)
+				part &= BITMAP_LAST_WORD_MASK(nbits);
+			k++;
+		}
+
+		*dst++ = part & 0xffffffffUL;
+		nwords--;
+
+#if BITS_PER_LONG == 64
+		if (nwords) {
+			part >>= 32;
+			*dst++ = part & 0xffffffffUL;
+			nwords--;
+		}
+#endif
+	}
+}
+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