Re: [PATCH net-next v7 01/19] lib/bitmap.c: conversion routines to/from u32 array
From: Andrew Morton <hidden>
Date: 2016-02-08 23:36:39
Also in:
linux-api, linux-mips, lkml
On Sun, 7 Feb 2016 17:08:45 -0800 David Decotigny [off-list ref] wrote:
quoted hunk ↗ jump to hunk
From: David Decotigny <decot-Ypc/8FJVVoBWk0Htik3J/w@public.gmane.org> 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.@@ -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. + */
This will leave the caller not knowing how many valid bits are actually present in the resulting bitmap. To determine that, the caller will need to perform (duplicated) math on `nbits' and `nwords'.
+void bitmap_from_u32array(unsigned long *bitmap, unsigned int nbits, + const u32 *buf, unsigned int nwords)
So how about we make this return the number of valid bits in *bitmap?
+/** + * 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)
Ditto.