From nobody Fri May 17 15:46:50 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; 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=linaro.org ARC-Seal: i=1; a=rsa-sha256; t=1615824402; cv=none; d=zohomail.com; s=zohoarc; b=ELXiY+efs/WDPZGjgDpMAWSM3UZpUMRjepwJLJrwqc27q/EitKTJmJ2HJlG9ZRGZ2RnuveSL6MWfyty6OpfmeRVLIPI2TPY/AijYM1PPlrD84KgPmoumHWcYHE3edVjzZzQv/Z6cKTlMQ3LZYe0aCqbqqPmg4adSFnc8S3hCtAU= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1615824402; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=jmCEBK3Fc6amVN11BmDrN7jUN/ivvV0qW5Tiif8OXLA=; b=OZS9260ZniEAHvH/zKDaVlh3HprBehuleRPUCZ/msTnRGCbOtiof7M5FEVIgSBNirMPiaUJv2pvayho4QkoYxBFGumHn4CLxv+4C9zdWAHCQchpIGBZu8aI/wDbUX9ks246E8G3xOgjXvRL0rK7YLU3A+dubgFwae80W/E2NFTo= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=fail; 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 header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1615824402459845.4644527491291; Mon, 15 Mar 2021 09:06:42 -0700 (PDT) Received: from localhost ([::1]:48844 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lLpjs-0003cR-Ot for importer@patchew.org; Mon, 15 Mar 2021 12:06:40 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51146) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lLpcC-0006ms-1v for qemu-devel@nongnu.org; Mon, 15 Mar 2021 11:58:44 -0400 Received: from mail-ot1-x336.google.com ([2607:f8b0:4864:20::336]:41760) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lLpcA-0004Me-Bj for qemu-devel@nongnu.org; Mon, 15 Mar 2021 11:58:43 -0400 Received: by mail-ot1-x336.google.com with SMTP id l23-20020a05683004b7b02901b529d1a2fdso5373759otd.8 for ; Mon, 15 Mar 2021 08:58:41 -0700 (PDT) Received: from localhost.localdomain (fixed-187-189-51-144.totalplay.net. [187.189.51.144]) by smtp.gmail.com with ESMTPSA id h24sm7278548otg.20.2021.03.15.08.58.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Mar 2021 08:58:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=jmCEBK3Fc6amVN11BmDrN7jUN/ivvV0qW5Tiif8OXLA=; b=YXSWRE/AidQ9nlBz+DRfSk7vUCp4zXAjLD/iPnYGOruNeoRRFkQ6rPFgpdWqv35QbN 49Yr5zJYBjVj0O/r8C38VZvEULelDSKT5Qtb7rTsUD4p0dQHzIEf6bsnykML28xnIjdj +jU76VVc6PZ47TYSA0hena5R+MIvFlHPF2cXzLQylWimWwdXpCogSuOg+ElrgqE84yrM WSjKF33ktx7dE3+qZv3bzd+itm4VdtQM5oqjcSl5WM0KzPqpbo05WsKmk3U96a/EQdjk Gj82Q8ZblDIx9m/0//bMNwkmUf4q5NuDqGF9PNRJzSy0pXQFHtm+RWxAIckv/Jfl0arm tEVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=jmCEBK3Fc6amVN11BmDrN7jUN/ivvV0qW5Tiif8OXLA=; b=i9/ZWkXH+wV6waE7pt7qa6Un6qjUavory8/WWKJmeLDpsbtnTrvf6qElqFhX8S6Ef4 6xHiTiIuyjNOLYjnDK2gRcL4uzJAzxesYAn11cDvX4EiIciT/ZFt4hrqNlIe3coRkCIu iF+cHFyuZ7+xfsnSWQmC+cv0T07Z6BQiG/g8dxO+s7gjsejWBELDCTnvfUum+mlPepmt IEwtWNsxLAz4CgC85NlU+wBmyGmCj/QVucHeCLjiqbA6bRp946rw633qmRHMMB9JjAet BVIA1Ry52D4AcCiY+1SPktk+M8o2Y/GOKCzv6TttKWiHHRsPnE7HPwYpLobERctZszZb y7Lg== X-Gm-Message-State: AOAM532YLEUgzUk7KQbhjU56YqlgFo88MIcXPbblgLVfIOPbvHel2pZW ufDg4hXUAiNU9CAMqhDHL7DC4Q5NUeLGbozh X-Google-Smtp-Source: ABdhPJwYzea6hvtp72rbNeFVjVs7Xe9+RKB2ova6EbeUMzv/8sYtqtm4klP1F6cUyiRNCQifO5UUlQ== X-Received: by 2002:a9d:618b:: with SMTP id g11mr14925483otk.313.1615823921044; Mon, 15 Mar 2021 08:58:41 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Subject: [PATCH v2 1/1] utils: Use fixed-point arithmetic in qemu_strtosz Date: Mon, 15 Mar 2021 09:58:35 -0600 Message-Id: <20210315155835.1970210-2-richard.henderson@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210315155835.1970210-1-richard.henderson@linaro.org> References: <20210315155835.1970210-1-richard.henderson@linaro.org> 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=2607:f8b0:4864:20::336; envelope-from=richard.henderson@linaro.org; helo=mail-ot1-x336.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: philmd@redhat.com, thuth@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Once we've parsed the fractional value, extract it into an integral 64-bit fraction. Perform the scaling with integer arithemetic, and simplify the overflow detection. Signed-off-by: Richard Henderson Reviewed-by: Eric Blake --- tests/unit/test-cutils.c | 2 +- util/cutils.c | 50 ++++++++++++++++++++++++++++------------ 2 files changed, 36 insertions(+), 16 deletions(-) diff --git a/tests/unit/test-cutils.c b/tests/unit/test-cutils.c index bad3a60993..e025b54c05 100644 --- a/tests/unit/test-cutils.c +++ b/tests/unit/test-cutils.c @@ -2128,7 +2128,7 @@ static void test_qemu_strtosz_float(void) str =3D "12.345M"; err =3D qemu_strtosz(str, &endptr, &res); g_assert_cmpint(err, =3D=3D, 0); - g_assert_cmpint(res, =3D=3D, (uint64_t) (12.345 * MiB)); + g_assert_cmpint(res, =3D=3D, (uint64_t) (12.345 * MiB + 0.5)); g_assert(endptr =3D=3D str + 7); } =20 diff --git a/util/cutils.c b/util/cutils.c index d89a40a8c3..c442882b88 100644 --- a/util/cutils.c +++ b/util/cutils.c @@ -275,10 +275,9 @@ static int do_strtosz(const char *nptr, const char **e= nd, int retval; const char *endptr, *f; unsigned char c; - bool mul_required =3D false, hex =3D false; - uint64_t val; + bool hex =3D false; + uint64_t val, valf =3D 0; int64_t mul; - double fraction =3D 0.0; =20 /* Parse integral portion as decimal. */ retval =3D qemu_strtou64(nptr, &endptr, 10, &val); @@ -308,17 +307,19 @@ static int do_strtosz(const char *nptr, const char **= end, * without fractional digits. If we see an exponent, treat * the entire input as invalid instead. */ + double fraction; + f =3D endptr; retval =3D qemu_strtod_finite(f, &endptr, &fraction); if (retval) { - fraction =3D 0.0; endptr++; } else if (memchr(f, 'e', endptr - f) || memchr(f, 'E', endptr - f= )) { endptr =3D nptr; retval =3D -EINVAL; goto out; - } else if (fraction !=3D 0) { - mul_required =3D true; + } else { + /* Extract into a 64-bit fixed-point fraction. */ + valf =3D (uint64_t)(fraction * 0x1p64); } } c =3D *endptr; @@ -333,16 +334,35 @@ static int do_strtosz(const char *nptr, const char **= end, mul =3D suffix_mul(default_suffix, unit); assert(mul > 0); } - if (mul =3D=3D 1 && mul_required) { - endptr =3D nptr; - retval =3D -EINVAL; - goto out; + if (mul =3D=3D 1) { + /* When a fraction is present, a scale is required. */ + if (valf !=3D 0) { + endptr =3D nptr; + retval =3D -EINVAL; + goto out; + } + } else { + uint64_t valh, tmp; + + /* Compute exact result: 64.64 x 64.0 -> 128.64 fixed point */ + mulu64(&val, &valh, val, mul); + mulu64(&valf, &tmp, valf, mul); + val +=3D tmp; + valh +=3D val < tmp; + + /* Round 0.5 upward. */ + tmp =3D valf >> 63; + val +=3D tmp; + valh +=3D val < tmp; + + /* Report overflow. */ + if (valh !=3D 0) { + retval =3D -ERANGE; + goto out; + } } - if (val > (UINT64_MAX - ((uint64_t) (fraction * mul))) / mul) { - retval =3D -ERANGE; - goto out; - } - *result =3D val * mul + (uint64_t) (fraction * mul); + + *result =3D val; retval =3D 0; =20 out: --=20 2.25.1