From patchwork Wed Mar 30 20:25:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lucas Mateus Martins Araujo e Castro X-Patchwork-Id: 12796336 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 970A3C433F5 for ; Wed, 30 Mar 2022 20:38:10 +0000 (UTC) Received: from localhost ([::1]:34038 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nZf4z-00021E-Gj for qemu-devel@archiver.kernel.org; Wed, 30 Mar 2022 16:38:09 -0400 Received: from eggs.gnu.org ([209.51.188.92]:50018) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nZeuO-0004UC-Rq; Wed, 30 Mar 2022 16:27:12 -0400 Received: from [187.72.171.209] (port=8867 helo=outlook.eldorado.org.br) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nZeuN-0001WS-3R; Wed, 30 Mar 2022 16:27:12 -0400 Received: from p9ibm ([10.10.71.235]) by outlook.eldorado.org.br over TLS secured channel with Microsoft SMTPSVC(8.5.9600.16384); Wed, 30 Mar 2022 17:25:42 -0300 Received: from eldorado.org.br (unknown [10.10.70.45]) by p9ibm (Postfix) with ESMTP id A8B968002AF; Wed, 30 Mar 2022 17:25:41 -0300 (-03) From: "Lucas Mateus Castro(alqotel)" To: qemu-devel@nongnu.org, qemu-ppc@nongnu.org Subject: [PATCH 06/10] Implemented unsigned 256-by-128 division Date: Wed, 30 Mar 2022 17:25:11 -0300 Message-Id: <20220330202515.66554-7-lucas.araujo@eldorado.org.br> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220330202515.66554-1-lucas.araujo@eldorado.org.br> References: <20220330202515.66554-1-lucas.araujo@eldorado.org.br> MIME-Version: 1.0 X-OriginalArrivalTime: 30 Mar 2022 20:25:42.0279 (UTC) FILETIME=[53F37970:01D84474] X-Host-Lookup-Failed: Reverse DNS lookup failed for 187.72.171.209 (failed) Received-SPF: pass client-ip=187.72.171.209; envelope-from=lucas.araujo@eldorado.org.br; helo=outlook.eldorado.org.br X-Spam_score_int: -4 X-Spam_score: -0.5 X-Spam_bar: / X-Spam_report: (-0.5 / 5.0 requ) BAYES_00=-1.9, PDS_HP_HELO_NORDNS=0.659, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no 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: , Cc: Peter Maydell , David Hildenbrand , Matheus Ferst , danielhb413@gmail.com, richard.henderson@linaro.org, Luis Pires , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , "Lucas Mateus Castro \(alqotel\)" , clg@kaod.org, =?utf-8?q?Alex_Benn=C3=A9e?= , David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: "Lucas Mateus Castro (alqotel)" Based on already existing QEMU implementation, created an unsigned 256 bit by 128 bit division needed to implement the vector divide extended unsigned instruction from PowerISA3.1 Signed-off-by: Lucas Mateus Castro (alqotel) --- include/qemu/host-utils.h | 15 +++++ include/qemu/int128.h | 20 ++++++ util/host-utils.c | 128 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 163 insertions(+) diff --git a/include/qemu/host-utils.h b/include/qemu/host-utils.h index ca979dc6cc..6479403935 100644 --- a/include/qemu/host-utils.h +++ b/include/qemu/host-utils.h @@ -32,6 +32,7 @@ #include "qemu/compiler.h" #include "qemu/bswap.h" +#include "qemu/int128.h" #ifdef CONFIG_INT128 static inline void mulu64(uint64_t *plow, uint64_t *phigh, @@ -142,6 +143,19 @@ static inline int clz64(uint64_t val) return val ? __builtin_clzll(val) : 64; } +/** + * clz128 - count leading zeros in a 128-bit value. + * @val: The value to search + */ +static inline int clz128(Int128 a) +{ + if (int128_gethi(a)) { + return clz64(int128_gethi(a)); + } else { + return clz64(int128_getlo(a)) + 64; + } +} + /** * clo64 - count leading ones in a 64-bit value. * @val: The value to search @@ -849,4 +863,5 @@ static inline uint64_t udiv_qrnnd(uint64_t *r, uint64_t n1, #endif } +Int128 divu256(Int128 *plow, Int128 *phigh, Int128 divisor); #endif diff --git a/include/qemu/int128.h b/include/qemu/int128.h index ca32b0b276..b1eb094525 100644 --- a/include/qemu/int128.h +++ b/include/qemu/int128.h @@ -128,11 +128,21 @@ static inline bool int128_ge(Int128 a, Int128 b) return a >= b; } +static inline bool int128_uge(Int128 a, Int128 b) +{ + return ((__uint128_t)a) >= ((__uint128_t)b); +} + static inline bool int128_lt(Int128 a, Int128 b) { return a < b; } +static inline bool int128_ult(Int128 a, Int128 b) +{ + return (__uint128_t)a < (__uint128_t)b; +} + static inline bool int128_le(Int128 a, Int128 b) { return a <= b; @@ -373,11 +383,21 @@ static inline bool int128_ge(Int128 a, Int128 b) return a.hi > b.hi || (a.hi == b.hi && a.lo >= b.lo); } +static inline bool int128_uge(Int128 a, Int128 b) +{ + return (uint64_t)a.hi > (uint64_t)b.hi || (a.hi == b.hi && a.lo >= b.lo); +} + static inline bool int128_lt(Int128 a, Int128 b) { return !int128_ge(a, b); } +static inline bool int128_ult(Int128 a, Int128 b) +{ + return !int128_uge(a, b); +} + static inline bool int128_le(Int128 a, Int128 b) { return int128_ge(b, a); diff --git a/util/host-utils.c b/util/host-utils.c index bcc772b8ec..a495cc820d 100644 --- a/util/host-utils.c +++ b/util/host-utils.c @@ -266,3 +266,131 @@ void ulshift(uint64_t *plow, uint64_t *phigh, int32_t shift, bool *overflow) *plow = *plow << shift; } } +/* + * Unsigned 256-by-128 division. + * Returns the remainder via r. + * Returns lower 128 bit of quotient. + * Needs a normalized divisor (most significant bit set to 1). + * + * Adapted from include/qemu/host-utils.h udiv_qrnnd, + * from the GNU Multi Precision Library - longlong.h __udiv_qrnnd + * (https://gmplib.org/repo/gmp/file/tip/longlong.h) + * + * Licensed under the GPLv2/LGPLv3 + */ +static Int128 udiv256_qrnnd(Int128 *r, Int128 n1, Int128 n0, Int128 d) +{ + Int128 d0, d1, q0, q1, r1, r0, m; + uint64_t mp0, mp1; + + d0 = int128_make64(int128_getlo(d)); + d1 = int128_make64(int128_gethi(d)); + + r1 = int128_remu(n1, d1); + q1 = int128_divu(n1, d1); + mp0 = int128_getlo(q1); + mp1 = int128_gethi(q1); + mulu128(&mp0, &mp1, int128_getlo(d0)); + m = int128_make128(mp0, mp1); + r1 = int128_make128(int128_gethi(n0), int128_getlo(r1)); + if (int128_ult(r1, m)) { + q1 = int128_sub(q1, int128_one()); + r1 = int128_add(r1, d); + if (int128_uge(r1, d)) { + if (int128_ult(r1, m)) { + q1 = int128_sub(q1, int128_one()); + r1 = int128_add(r1, d); + } + } + } + r1 = int128_sub(r1, m); + + r0 = int128_remu(r1, d1); + q0 = int128_divu(r1, d1); + mp0 = int128_getlo(q0); + mp1 = int128_gethi(q0); + mulu128(&mp0, &mp1, int128_getlo(d0)); + m = int128_make128(mp0, mp1); + r0 = int128_make128(int128_getlo(n0), int128_getlo(r0)); + if (int128_ult(r0, m)) { + q0 = int128_sub(q0, int128_one()); + r0 = int128_add(r0, d); + if (int128_uge(r0, d)) { + if (int128_ult(r0, m)) { + q0 = int128_sub(q0, int128_one()); + r0 = int128_add(r0, d); + } + } + } + r0 = int128_sub(r0, m); + + *r = r0; + return int128_or(int128_lshift(q1, 64), q0); +} + +/* + * Unsigned 256-by-128 division. + * Returns the remainder. + * Returns quotient via plow and phigh. + * Also returns the remainder via the function return value. + */ +Int128 divu256(Int128 *plow, Int128 *phigh, Int128 divisor) +{ + Int128 dhi = *phigh; + Int128 dlo = *plow; + Int128 rem, dhighest; + int sh; + + if (!int128_nz(divisor) || !int128_nz(dhi)) { + *plow = int128_divu(dlo, divisor); + *phigh = int128_zero(); + return int128_remu(dlo, divisor); + } else { + sh = clz128(divisor); + + if (int128_ult(dhi, divisor)) { + if (sh != 0) { + /* normalize the divisor, shifting the dividend accordingly */ + divisor = int128_lshift(divisor, sh); + dhi = int128_or(int128_lshift(dhi, sh), + int128_urshift(dlo, (128 - sh))); + dlo = int128_lshift(dlo, sh); + } + + *phigh = int128_zero(); + *plow = udiv256_qrnnd(&rem, dhi, dlo, divisor); + } else { + if (sh != 0) { + /* normalize the divisor, shifting the dividend accordingly */ + divisor = int128_lshift(divisor, sh); + dhighest = int128_rshift(dhi, (128 - sh)); + dhi = int128_or(int128_lshift(dhi, sh), + int128_urshift(dlo, (128 - sh))); + dlo = int128_lshift(dlo, sh); + + *phigh = udiv256_qrnnd(&dhi, dhighest, dhi, divisor); + } else { + /** + * dhi >= divisor + * Since the MSB of divisor is set (sh == 0), + * (dhi - divisor) < divisor + * + * Thus, the high part of the quotient is 1, and we can + * calculate the low part with a single call to udiv_qrnnd + * after subtracting divisor from dhi + */ + dhi = int128_sub(dhi, divisor); + *phigh = int128_one(); + } + + *plow = udiv256_qrnnd(&rem, dhi, dlo, divisor); + } + + /* + * since the dividend/divisor might have been normalized, + * the remainder might also have to be shifted back + */ + rem = int128_urshift(rem, sh); + return rem; + } +}