From patchwork Fri Apr 28 14:47:48 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lawrence Hunter X-Patchwork-Id: 13226570 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5D2D8C77B60 for ; Fri, 28 Apr 2023 15:28:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346405AbjD1P2P (ORCPT ); Fri, 28 Apr 2023 11:28:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44502 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346038AbjD1P2M (ORCPT ); Fri, 28 Apr 2023 11:28:12 -0400 Received: from imap4.hz.codethink.co.uk (imap4.hz.codethink.co.uk [188.40.203.114]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3BE696199 for ; Fri, 28 Apr 2023 08:27:45 -0700 (PDT) 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 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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 +/** + * 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); } +/** + * 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