Return-Path: From: Andrei Emeltchenko To: linux-bluetooth@vger.kernel.org Subject: [PATCHv3 3/8] shared/utils: Add helpers for bitfield fast uid generation Date: Fri, 13 Feb 2015 16:52:44 +0200 Message-Id: <1423839169-8944-4-git-send-email-Andrei.Emeltchenko.news@gmail.com> In-Reply-To: <1423839169-8944-1-git-send-email-Andrei.Emeltchenko.news@gmail.com> References: <1423839169-8944-1-git-send-email-Andrei.Emeltchenko.news@gmail.com> Sender: linux-bluetooth-owner@vger.kernel.org List-ID: From: Andrei Emeltchenko For small unique id generation we may use bitfield since it is very fast and memory efficient. If we need to generate id from 1 to 64 helper functions are added to utils. --- src/shared/util.c | 24 ++++++++++++++++++++++++ src/shared/util.h | 3 +++ 2 files changed, 27 insertions(+) diff --git a/src/shared/util.c b/src/shared/util.c index 74ffb08..3ae6b9e 100644 --- a/src/shared/util.c +++ b/src/shared/util.c @@ -106,3 +106,27 @@ unsigned char util_get_dt(const char *parent, const char *name) return DT_UNKNOWN; } + +/* Helpers for bitfield operations */ +/* Find unique id from 1 to max */ +uint8_t util_get_bitmap64_uid(uint64_t *bitmap, uint8_t max) +{ + uint64_t temp = *bitmap >> 1; + uint64_t id = 1; + + for (; temp & 0x01; temp >>= 1) + id++; + + if (id > max) + return 0; + + *bitmap |= 0x01l << id; + + return id; +} + +/* Clear id bit in bitmap */ +void util_clear_bitmap64(uint64_t *bitmap, uint8_t id) +{ + *bitmap &= ~(0x01l << id); +} diff --git a/src/shared/util.h b/src/shared/util.h index 8437662..8f28c24 100644 --- a/src/shared/util.h +++ b/src/shared/util.h @@ -93,6 +93,9 @@ void util_hexdump(const char dir, const unsigned char *buf, size_t len, unsigned char util_get_dt(const char *parent, const char *name); +uint8_t util_get_bitmap64_uid(uint64_t *bitmap, uint8_t max); +void util_clear_bitmap64(uint64_t *bitmap, uint8_t id); + static inline void bswap_128(const void *src, void *dst) { const uint8_t *s = src; -- 2.1.0