Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932923AbZLOUxh (ORCPT ); Tue, 15 Dec 2009 15:53:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760264AbZLOUxe (ORCPT ); Tue, 15 Dec 2009 15:53:34 -0500 Received: from mail-gx0-f211.google.com ([209.85.217.211]:50059 "EHLO mail-gx0-f211.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760882AbZLOUxX (ORCPT ); Tue, 15 Dec 2009 15:53:23 -0500 From: Justin Madru To: linux-kernel@vger.kernel.org Cc: Justin Madru , gregkh@suse.de, error27@gmail.com, ray-lk@madrabbit.org Subject: [PATCH] staging: s5k3e2fx.c: simplify complexity by factoring Date: Tue, 15 Dec 2009 12:52:10 -0800 Message-Id: <1260910330-3409-1-git-send-email-jdm64@gawab.com> X-Mailer: git-send-email 1.6.5.6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1768 Lines: 51 the code was looping, seting s_move[i] to the following calculations if (actual_step >= 0) s_move[i] = ((((i + 1) * gain + 0x200) - (i * gain + 0x200)) / 0x400); else s_move[i] = ((((i + 1) * gain - 0x200) - (i * gain - 0x200)) / 0x400); but, this code redues to the expression s_move[i] = gain >> 10; The reason for the complexity was to generate a step function with integer division and rounding to land on specific values. But these calculations can be simplified to the following code: gain = ((actual_step << 10) / 5) >> 10; for (i = 0; i <= 4; i++) s_move[i] = gain; --- drivers/staging/dream/camera/s5k3e2fx.c | 10 +++------- 1 files changed, 3 insertions(+), 7 deletions(-) diff --git a/drivers/staging/dream/camera/s5k3e2fx.c b/drivers/staging/dream/camera/s5k3e2fx.c index edba198..66582af 100644 --- a/drivers/staging/dream/camera/s5k3e2fx.c +++ b/drivers/staging/dream/camera/s5k3e2fx.c @@ -1093,14 +1093,10 @@ static int32_t s5k3e2fx_move_focus(int direction, int32_t num_steps) actual_step = step_direction * (int16_t)num_steps; pos_offset = init_code + s5k3e2fx_ctrl->curr_lens_pos; - gain = actual_step * 0x400 / 5; + gain = ((actual_step << 10) / 5) >> 10; - for (i = 0; i <= 4; i++) { - if (actual_step >= 0) - s_move[i] = ((((i+1)*gain+0x200) - (i*gain+0x200))/0x400); - else - s_move[i] = ((((i+1)*gain-0x200) - (i*gain-0x200))/0x400); - } + for (i = 0; i <= 4; i++) + s_move[i] = gain; /* Ring Damping Code */ for (i = 0; i <= 4; i++) { -- 1.6.5.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/