/* $XFree86: xc/programs/Xserver/hw/xfree86/drivers/s3virge/s3v_dac.c,v 1.5 2004/02/13 23:58:43 dawes Exp $ */ /* * Copyright (C) 1994-1998 The XFree86 Project, Inc. * All rights reserved. * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject * to the following conditions: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions, and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer * in the documentation and/or other materials provided with the * distribution, and in the same place and form as other copyright, * license and disclaimer information. * * 3. The end-user documentation included with the redistribution, * if any, must include the following acknowledgment: "This product * includes software developed by The XFree86 Project, Inc * (http://www.xfree86.org/) and its contributors", in the same * place and form as other third-party acknowledgments. Alternately, * this acknowledgment may appear in the software itself, in the * same form and location as other such third-party acknowledgments. * * 4. Except as contained in this notice, the name of The XFree86 * Project, Inc shall not be used in advertising or otherwise to * promote the sale, use or other dealings in this Software without * prior written authorization from The XFree86 Project, Inc. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE XFREE86 PROJECT, INC OR ITS CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /* * s3v_dac.c * Port to 4.0 design level * * S3 ViRGE driver * * * s3vcommonCalcClock from S3gendac.c in pre 4.0 tree. * */ #include "s3v.h" #define BASE_FREQ 14.31818 /* MHz */ /* function */ void S3VCommonCalcClock(ScrnInfoPtr pScrn, DisplayModePtr mode, long freq, int min_m, int min_n1, int max_n1, int min_n2, int max_n2, long freq_min, long freq_max, unsigned char * mdiv, unsigned char * ndiv) { double ffreq, ffreq_min, ffreq_max, ffreq_min_warn; double div, diff, best_diff; unsigned int m; unsigned char n1, n2; unsigned char best_n1=16+2, best_n2=2, best_m=125+2; ffreq = freq / 1000.0 / BASE_FREQ; ffreq_min = freq_min / 1000.0 / BASE_FREQ; ffreq_max = freq_max / 1000.0 / BASE_FREQ; /* Doublescan modes can run at half the min frequency */ /* But only use that value for warning and changing */ /* ffreq, don't change the actual min used for clock calcs below. */ if(mode->Flags & V_DBLSCAN && ffreq_min) ffreq_min_warn = ffreq_min / 2; else ffreq_min_warn = ffreq_min; if (ffreq < ffreq_min_warn / (1<<max_n2)) { xf86DrvMsg(pScrn->scrnIndex, X_ERROR, "invalid frequency %1.3f MHz [freq <= %1.3f MHz]\n", ffreq*BASE_FREQ, ffreq_min_warn*BASE_FREQ / (1<<max_n2)); ffreq = ffreq_min_warn / (1<<max_n2); } if (ffreq > ffreq_max / (1<<min_n2)) { xf86DrvMsg(pScrn->scrnIndex, X_ERROR, "invalid frequency %1.3f MHz [freq >= %1.3f MHz]\n", ffreq*BASE_FREQ, ffreq_max*BASE_FREQ / (1<<min_n2)); ffreq = ffreq_max / (1<<min_n2); } /* work out suitable timings */ best_diff = ffreq; for (n2=min_n2; n2<=max_n2; n2++) { for (n1 = min_n1+2; n1 <= max_n1+2; n1++) { m = (int)(ffreq * n1 * (1<<n2) + 0.5) ; if (m < min_m+2 || m > 127+2) continue; div = (double)(m) / (double)(n1); if ((div >= ffreq_min) && (div <= ffreq_max)) { diff = ffreq - div / (1<<n2); if (diff < 0.0) diff = -diff; if (diff < best_diff) { best_diff = diff; best_m = m; best_n1 = n1; best_n2 = n2; } } } } #ifdef EXTENDED_DEBUG ErrorF("Clock parameters for %1.6f MHz: m=%d, n1=%d, n2=%d\n", ((double)(best_m) / (double)(best_n1) / (1 << best_n2)) * BASE_FREQ, best_m-2, best_n1-2, best_n2); #endif if (max_n1 == 63) *ndiv = (best_n1 - 2) | (best_n2 << 6); else *ndiv = (best_n1 - 2) | (best_n2 << 5); *mdiv = best_m - 2; }