From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail-ed1-x549.google.com ([2a00:1450:4864:20::549]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qLMXW-003sKb-1P for linux-arm-kernel@lists.infradead.org; Mon, 17 Jul 2023 11:38:08 +0000 Received: by mail-ed1-x549.google.com with SMTP id 4fb4d7f45d1cf-51e2295e74eso2969907a12.0 for ; Mon, 17 Jul 2023 04:37:17 -0700 (PDT) Date: Mon, 17 Jul 2023 13:37:04 +0200 In-Reply-To: <20230717113709.328671-1-glider@google.com> Mime-Version: 1.0 References: <20230717113709.328671-1-glider@google.com> Message-ID: <20230717113709.328671-2-glider@google.com> Subject: [PATCH v3 1/5] lib/bitmap: add bitmap_{set,get}_value() From: Alexander Potapenko List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+lwn-linux-arm-kernel=archive.lwn.net@lists.infradead.org List-Archive: To: glider@google.com, catalin.marinas@arm.com, will@kernel.org, pcc@google.com, andreyknvl@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, yury.norov@gmail.com Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, eugenis@google.com, syednwaris@gmail.com, william.gray@linaro.org, Arnd Bergmann The two new functions allow setting/getting values of length up to BITS_PER_LONG bits at arbitrary position in the bitmap. The code was taken from "bitops: Introduce the for_each_set_clump macro" by Syed Nayyar Waris with a couple of minor changes: - instead of using roundup(), which adds an unnecessary dependency on , we calculate space as BITS_PER_LONG-offset; - indentation is reduced by not using else-clauses (suggested by checkpatch for bitmap_get_value()) Cc: Arnd Bergmann Signed-off-by: Syed Nayyar Waris Signed-off-by: William Breathitt Gray Link: https://lore.kernel.org/lkml/fe12eedf3666f4af5138de0e70b67a07c7f40338.1592224129.git.syednwaris@gmail.com/ Suggested-by: Yury Norov Signed-off-by: Alexander Potapenko --- include/linux/bitmap.h | 57 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 03644237e1efb..4559366084988 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -76,7 +76,11 @@ struct device; * bitmap_to_arr32(buf, src, nbits) Copy nbits from buf to u32[] dst * bitmap_to_arr64(buf, src, nbits) Copy nbits from buf to u64[] dst * bitmap_get_value8(map, start) Get 8bit value from map at start + * bitmap_get_value(map, start, nbits) Get bit value of size 'nbits' + * from map at start * bitmap_set_value8(map, value, start) Set 8bit value to map at start + * bitmap_set_value(map, value, start, nbits) Set bit value of size 'nbits' + * of map at start * * Note, bitmap_zero() and bitmap_fill() operate over the region of * unsigned longs, that is, bits behind bitmap till the unsigned long @@ -583,6 +587,31 @@ static inline unsigned long bitmap_get_value8(const unsigned long *map, return (map[index] >> offset) & 0xFF; } +/** + * bitmap_get_value - get a value of n-bits from the memory region + * @map: address to the bitmap memory region + * @start: bit offset of the n-bit value + * @nbits: size of value in bits + * + * Returns value of nbits located at the @start bit offset within the @map + * memory region. + */ +static inline unsigned long bitmap_get_value(const unsigned long *map, + unsigned long start, + unsigned long nbits) +{ + const size_t index = BIT_WORD(start); + const unsigned long offset = start % BITS_PER_LONG; + const unsigned long space = BITS_PER_LONG - offset; + unsigned long value_low, value_high; + + if (space >= nbits) + return (map[index] >> offset) & GENMASK(nbits - 1, 0); + value_low = map[index] & BITMAP_FIRST_WORD_MASK(start); + value_high = map[index + 1] & BITMAP_LAST_WORD_MASK(start + nbits); + return (value_low >> offset) | (value_high << space); +} + /** * bitmap_set_value8 - set an 8-bit value within a memory region * @map: address to the bitmap memory region @@ -599,6 +628,34 @@ static inline void bitmap_set_value8(unsigned long *map, unsigned long value, map[index] |= value << offset; } +/** + * bitmap_set_value - set n-bit value within a memory region + * @map: address to the bitmap memory region + * @value: value of nbits + * @start: bit offset of the n-bit value + * @nbits: size of value in bits + */ +static inline void bitmap_set_value(unsigned long *map, + unsigned long value, + unsigned long start, unsigned long nbits) +{ + const size_t index = BIT_WORD(start); + const unsigned long offset = start % BITS_PER_LONG; + const unsigned long space = BITS_PER_LONG - offset; + + value &= GENMASK(nbits - 1, 0); + + if (space >= nbits) { + map[index] &= ~(GENMASK(nbits + offset - 1, offset)); + map[index] |= value << offset; + return; + } + map[index] &= ~BITMAP_FIRST_WORD_MASK(start); + map[index] |= value << offset; + map[index + 1] &= ~BITMAP_LAST_WORD_MASK(start + nbits); + map[index + 1] |= (value >> space); +} + #endif /* __ASSEMBLY__ */ #endif /* __LINUX_BITMAP_H */ -- 2.41.0.255.g8b1d071c50-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel