From patchwork Sat Sep 28 02:26:09 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andreas Rheinhardt X-Patchwork-Id: 15354 Return-Path: X-Original-To: patchwork@ffaux-bg.ffmpeg.org Delivered-To: patchwork@ffaux-bg.ffmpeg.org Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by ffaux.localdomain (Postfix) with ESMTP id 72EEF4475E8 for ; Sat, 28 Sep 2019 05:39:14 +0300 (EEST) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 4D96E689BD9; Sat, 28 Sep 2019 05:39:14 +0300 (EEST) X-Original-To: ffmpeg-devel@ffmpeg.org Delivered-To: ffmpeg-devel@ffmpeg.org Received: from mail-wr1-f66.google.com (mail-wr1-f66.google.com [209.85.221.66]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 0A04F6882EA for ; Sat, 28 Sep 2019 05:39:08 +0300 (EEST) Received: by mail-wr1-f66.google.com with SMTP id q17so5108885wrx.10 for ; Fri, 27 Sep 2019 19:39:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=qtbeLJDk/4Kd7PY4UoHIRYhG/xrLW6BqBS41zrrLEpo=; b=Np/FnbJrR0xhE/7g3HjzBL3legQbblCFmcjZc6+VOzjLsB1MfTh1gTD9RRfGFqKX+E dnqvcaGRy+3BTUPz+uLL3/0GJrptvSW86Foo18kpz+XPV4FCAis8R9neqdOFeis2YmmT kwgB8ZQqcIP/4AX16lIt6SfoO9/9EuSnAiNNXhyX9S2xo0/TC+IaiR+z/TCYi0mV3ACO PpUE9+8CWSWWawJP+ciXEPM/5ThknJr6tAnEq/lZKVrGoSq0cdUH/6UkdEowvdG93Qd4 E6FdP46MGcc0yFQ1pehsb0rfC885NxLOxiYTjMGw/1fIX8m2O/DvuzpNfiIu6twNjVVU Lykw== 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=qtbeLJDk/4Kd7PY4UoHIRYhG/xrLW6BqBS41zrrLEpo=; b=NqYQ7EROfOuXd/j9Ny0siSHK0xye2t0UuufRqvp8RDlNcCo4DKCmeLaGp8/H6Rq7pQ sJD9mpn6fT9Clr8Xy18+o188YVFexBxdEUfjIlvsxj7gioxIcr/hC2KJjGArK110znMG ErEpGENZ5cR8mwTOxcd68S/Gh2EBoQJAaF6F7J7eS2TYyV2EZt2z2n/WR2TuxQKXZVx1 XEOEl51wqYHIys+SmYKwrXgLgkehBxBvAtbszuRiiSEdzFOUYZxel6l+v6cs1peGlDyQ UV04JLa9A8zIZJBpUGrgp1uXRZTNDzr3fBezwBIE9yKzjfWKRk04r3TPJ2GK55qUThSi yd/w== X-Gm-Message-State: APjAAAVWer4KppcYZO8sK7iGeUt1S5GuWpe26ZlnHZCSlV+fpTZjW57U nh1GIKtOtKKI+xnUCa2BsZTZ9bEA X-Google-Smtp-Source: APXvYqznrcVhR+kfBd+BiMJvCDwokhvCedhfbr8LNVfTALmcq9/B7yNSo6SoP8HF04OM7lU66z1APA== X-Received: by 2002:a5d:500b:: with SMTP id e11mr5249336wrt.285.1569638043972; Fri, 27 Sep 2019 19:34:03 -0700 (PDT) Received: from sblaptop.fritz.box (ipbcc0f857.dynamic.kabel-deutschland.de. [188.192.248.87]) by smtp.gmail.com with ESMTPSA id r7sm4484231wrx.87.2019.09.27.19.34.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Sep 2019 19:34:03 -0700 (PDT) From: Andreas Rheinhardt To: ffmpeg-devel@ffmpeg.org Date: Sat, 28 Sep 2019 04:26:09 +0200 Message-Id: <20190928022610.5903-14-andreas.rheinhardt@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190928022610.5903-1-andreas.rheinhardt@gmail.com> References: <20190928022610.5903-1-andreas.rheinhardt@gmail.com> MIME-Version: 1.0 Subject: [FFmpeg-devel] [PATCH v2 14/15] avcodec/j2kenc: Simplify computations X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Cc: Andreas Rheinhardt Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" 1. (1 << (c - 1)) & ~((1 << c) - 1) is always zero. This together with the fact that a square is always nonnegative (there's no overflow) allows to remove a FFMAX. 2. The discriminant of the polynomial i * i - 2^(F+1) * i + 2^(F - 1) + 2^(2 * F) is negative; hence this polynomial has no real solutions, i.e. its sign doesn't change and is always positive. This allows to remove a FFMAX. Signed-off-by: Andreas Rheinhardt --- libavcodec/j2kenc.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/libavcodec/j2kenc.c b/libavcodec/j2kenc.c index b5ac06b906..0a1421c844 100644 --- a/libavcodec/j2kenc.c +++ b/libavcodec/j2kenc.c @@ -522,13 +522,12 @@ static void init_luts(void) for (i = 0; i < (1 << NMSEDEC_BITS); i++){ lut_nmsedec_sig[i] = FFMAX((6 * i - (9 << (NMSEDEC_FRACBITS - 1))) * (1 << (12 - NMSEDEC_FRACBITS)), 0); - lut_nmsedec_sig0[i] = FFMAX((i*i + (1<> (NMSEDEC_BITS-2)&2) + 1; lut_nmsedec_ref[i] = FFMAX((-2 * i + (1 << NMSEDEC_FRACBITS) + a * i - (a * a << (NMSEDEC_FRACBITS - 2))) * (1 << (13 - NMSEDEC_FRACBITS)), 0); - lut_nmsedec_ref0[i] = FFMAX(((i * i - (i << (NMSEDEC_FRACBITS + 1)) + (1 << (NMSEDEC_FRACBITS - 1)) + (1 << 2 * NMSEDEC_FRACBITS)) & mask) - << 1, 0); + lut_nmsedec_ref0[i] = ((i * i - (i << (NMSEDEC_FRACBITS + 1)) + (1 << (NMSEDEC_FRACBITS - 1)) + (1 << 2 * NMSEDEC_FRACBITS)) & mask) << 1; } }