From nobody Mon Feb 9 09:15:36 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=codethink.co.uk Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1682693391912954.021204542115; Fri, 28 Apr 2023 07:49:51 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1psPOw-0006MB-9a; Fri, 28 Apr 2023 10:48:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1psPOp-0006Gd-EA; Fri, 28 Apr 2023 10:48:40 -0400 Received: from imap4.hz.codethink.co.uk ([188.40.203.114]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1psPOl-0002Co-V7; Fri, 28 Apr 2023 10:48:38 -0400 Received: from [167.98.27.226] (helo=lawrence-thinkpad.guest.codethink.co.uk) by imap4.hz.codethink.co.uk with esmtpsa (Exim 4.94.2 #2 (Debian)) id 1psPON-005zz5-PZ; Fri, 28 Apr 2023 15:48:11 +0100 From: Lawrence Hunter To: qemu-devel@nongnu.org Cc: dickon.hood@codethink.co.uk, nazar.kazakov@codethink.co.uk, kiran.ostrolenk@codethink.co.uk, frank.chang@sifive.com, palmer@dabbelt.com, alistair.francis@wdc.com, bin.meng@windriver.com, pbonzini@redhat.com, philipp.tomsich@vrull.eu, kvm@vger.kernel.org, qemu-riscv@nongnu.org, richard.henderson@linaro.org Subject: [PATCH v3 10/19] qemu/host-utils.h: Add clz and ctz functions for lower-bit integers Date: Fri, 28 Apr 2023 15:47:48 +0100 Message-Id: <20230428144757.57530-11-lawrence.hunter@codethink.co.uk> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230428144757.57530-1-lawrence.hunter@codethink.co.uk> References: <20230428144757.57530-1-lawrence.hunter@codethink.co.uk> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=188.40.203.114; envelope-from=lawrence.hunter@codethink.co.uk; helo=imap4.hz.codethink.co.uk X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1682693393385100004 Content-Type: text/plain; charset="utf-8" From: Kiran Ostrolenk This is for use in the RISC-V vclz and vctz instructions (implemented in proceeding commit). Signed-off-by: Kiran Ostrolenk Reviewed-by: Richard Henderson --- include/qemu/host-utils.h | 54 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) diff --git a/include/qemu/host-utils.h b/include/qemu/host-utils.h index 3ce62bf4a56..d3b4dce6a93 100644 --- a/include/qemu/host-utils.h +++ b/include/qemu/host-utils.h @@ -107,6 +107,36 @@ static inline uint64_t muldiv64(uint64_t a, uint32_t b= , uint32_t c) } #endif =20 +/** + * clz8 - count leading zeros in a 8-bit value. + * @val: The value to search + * + * Returns 8 if the value is zero. Note that the GCC builtin is + * undefined if the value is zero. + * + * Note that the GCC builtin will upcast its argument to an `unsigned int` + * so this function subtracts off the number of prepended zeroes. + */ +static inline int clz8(uint8_t val) +{ + return val ? __builtin_clz(val) - 24 : 8; +} + +/** + * clz16 - count leading zeros in a 16-bit value. + * @val: The value to search + * + * Returns 16 if the value is zero. Note that the GCC builtin is + * undefined if the value is zero. + * + * Note that the GCC builtin will upcast its argument to an `unsigned int` + * so this function subtracts off the number of prepended zeroes. + */ +static inline int clz16(uint16_t val) +{ + return val ? __builtin_clz(val) - 16 : 16; +} + /** * clz32 - count leading zeros in a 32-bit value. * @val: The value to search @@ -153,6 +183,30 @@ static inline int clo64(uint64_t val) return clz64(~val); } =20 +/** + * ctz8 - count trailing zeros in a 8-bit value. + * @val: The value to search + * + * Returns 8 if the value is zero. Note that the GCC builtin is + * undefined if the value is zero. + */ +static inline int ctz8(uint8_t val) +{ + return val ? __builtin_ctz(val) : 8; +} + +/** + * ctz16 - count trailing zeros in a 16-bit value. + * @val: The value to search + * + * Returns 16 if the value is zero. Note that the GCC builtin is + * undefined if the value is zero. + */ +static inline int ctz16(uint16_t val) +{ + return val ? __builtin_ctz(val) : 16; +} + /** * ctz32 - count trailing zeros in a 32-bit value. * @val: The value to search --=20 2.40.1