389 lines
13 KiB
C
389 lines
13 KiB
C
/*
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* gtf.c Generate mode timings using the GTF Timing Standard
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*
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* gcc gtf.c -o gtf -lm -Wall
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*
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* Copyright (c) 2001, Andy Ritger aritger@nvidia.com
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* o Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* o Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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* o Neither the name of NVIDIA nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
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* NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* This program is based on the Generalized Timing Formula(GTF TM)
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* Standard Version: 1.0, Revision: 1.0
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*
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* The GTF Document contains the following Copyright information:
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*
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* Copyright (c) 1994, 1995, 1996 - Video Electronics Standards
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* Association. Duplication of this document within VESA member
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* companies for review purposes is permitted. All other rights
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* reserved.
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*
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* While every precaution has been taken in the preparation
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* of this standard, the Video Electronics Standards Association and
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* its contributors assume no responsibility for errors or omissions,
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* and make no warranties, expressed or implied, of functionality
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* of suitability for any purpose. The sample code contained within
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* this standard may be used without restriction.
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*
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*
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*
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* The GTF EXCEL(TM) SPREADSHEET, a sample (and the definitive)
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* implementation of the GTF Timing Standard, is available at:
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*
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* ftp://ftp.vesa.org/pub/GTF/GTF_V1R1.xls
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*/
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/* Ruthlessly converted to server code by Adam Jackson <ajax@redhat.com> */
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#ifdef HAVE_XORG_CONFIG_H
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# include <xorg-config.h>
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#else
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#endif
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#include "xf86.h"
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#include "xf86Modes.h"
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#include <string.h>
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#define MARGIN_PERCENT 1.8 /* % of active vertical image */
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#define CELL_GRAN 8.0 /* assumed character cell granularity */
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#define MIN_PORCH 1 /* minimum front porch */
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#define V_SYNC_RQD 3 /* width of vsync in lines */
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#define H_SYNC_PERCENT 8.0 /* width of hsync as % of total line */
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#define MIN_VSYNC_PLUS_BP 550.0 /* min time of vsync + back porch (microsec) */
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#define M 600.0 /* blanking formula gradient */
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#define C 40.0 /* blanking formula offset */
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#define K 128.0 /* blanking formula scaling factor */
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#define J 20.0 /* blanking formula scaling factor */
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/* C' and M' are part of the Blanking Duty Cycle computation */
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#define C_PRIME (((C - J) * K/256.0) + J)
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#define M_PRIME (K/256.0 * M)
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/*
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* xf86GTFMode() - as defined by the GTF Timing Standard, compute the
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* Stage 1 Parameters using the vertical refresh frequency. In other
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* words: input a desired resolution and desired refresh rate, and
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* output the GTF mode timings.
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*
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* XXX All the code is in place to compute interlaced modes, but I don't
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* feel like testing it right now.
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*
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* XXX margin computations are implemented but not tested (nor used by
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* XServer of fbset mode descriptions, from what I can tell).
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*/
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DisplayModePtr
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xf86GTFMode(int h_pixels, int v_lines, float freq, int interlaced, int margins)
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{
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DisplayModeRec *mode = xnfcalloc(1, sizeof(DisplayModeRec));
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float h_pixels_rnd;
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float v_lines_rnd;
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float v_field_rate_rqd;
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float top_margin;
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float bottom_margin;
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float interlace;
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float h_period_est;
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float vsync_plus_bp;
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float v_back_porch;
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float total_v_lines;
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float v_field_rate_est;
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float h_period;
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float v_field_rate;
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float v_frame_rate;
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float left_margin;
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float right_margin;
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float total_active_pixels;
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float ideal_duty_cycle;
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float h_blank;
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float total_pixels;
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float pixel_freq;
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float h_freq;
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float h_sync;
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float h_front_porch;
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float v_odd_front_porch_lines;
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/* 1. In order to give correct results, the number of horizontal
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* pixels requested is first processed to ensure that it is divisible
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* by the character size, by rounding it to the nearest character
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* cell boundary:
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*
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* [H PIXELS RND] = ((ROUND([H PIXELS]/[CELL GRAN RND],0))*[CELLGRAN RND])
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*/
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h_pixels_rnd = rint((float) h_pixels / CELL_GRAN) * CELL_GRAN;
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/* 2. If interlace is requested, the number of vertical lines assumed
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* by the calculation must be halved, as the computation calculates
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* the number of vertical lines per field. In either case, the
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* number of lines is rounded to the nearest integer.
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*
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* [V LINES RND] = IF([INT RQD?]="y", ROUND([V LINES]/2,0),
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* ROUND([V LINES],0))
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*/
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v_lines_rnd = interlaced ?
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rint((float) v_lines) / 2.0 :
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rint((float) v_lines);
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/* 3. Find the frame rate required:
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*
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* [V FIELD RATE RQD] = IF([INT RQD?]="y", [I/P FREQ RQD]*2,
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* [I/P FREQ RQD])
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*/
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v_field_rate_rqd = interlaced ? (freq * 2.0) : (freq);
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/* 4. Find number of lines in Top margin:
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*
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* [TOP MARGIN (LINES)] = IF([MARGINS RQD?]="Y",
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* ROUND(([MARGIN%]/100*[V LINES RND]),0),
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* 0)
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*/
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top_margin = margins ? rint(MARGIN_PERCENT / 100.0 * v_lines_rnd) : (0.0);
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/* 5. Find number of lines in Bottom margin:
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*
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* [BOT MARGIN (LINES)] = IF([MARGINS RQD?]="Y",
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* ROUND(([MARGIN%]/100*[V LINES RND]),0),
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* 0)
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*/
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bottom_margin = margins ? rint(MARGIN_PERCENT/100.0 * v_lines_rnd) : (0.0);
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/* 6. If interlace is required, then set variable [INTERLACE]=0.5:
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*
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* [INTERLACE]=(IF([INT RQD?]="y",0.5,0))
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*/
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interlace = interlaced ? 0.5 : 0.0;
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/* 7. Estimate the Horizontal period
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*
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* [H PERIOD EST] = ((1/[V FIELD RATE RQD]) - [MIN VSYNC+BP]/1000000) /
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* ([V LINES RND] + (2*[TOP MARGIN (LINES)]) +
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* [MIN PORCH RND]+[INTERLACE]) * 1000000
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*/
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h_period_est = (((1.0/v_field_rate_rqd) - (MIN_VSYNC_PLUS_BP/1000000.0))
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/ (v_lines_rnd + (2*top_margin) + MIN_PORCH + interlace)
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* 1000000.0);
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/* 8. Find the number of lines in V sync + back porch:
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*
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* [V SYNC+BP] = ROUND(([MIN VSYNC+BP]/[H PERIOD EST]),0)
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*/
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vsync_plus_bp = rint(MIN_VSYNC_PLUS_BP/h_period_est);
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/* 9. Find the number of lines in V back porch alone:
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*
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* [V BACK PORCH] = [V SYNC+BP] - [V SYNC RND]
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*
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* XXX is "[V SYNC RND]" a typo? should be [V SYNC RQD]?
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*/
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v_back_porch = vsync_plus_bp - V_SYNC_RQD;
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/* 10. Find the total number of lines in Vertical field period:
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*
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* [TOTAL V LINES] = [V LINES RND] + [TOP MARGIN (LINES)] +
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* [BOT MARGIN (LINES)] + [V SYNC+BP] + [INTERLACE] +
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* [MIN PORCH RND]
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*/
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total_v_lines = v_lines_rnd + top_margin + bottom_margin + vsync_plus_bp +
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interlace + MIN_PORCH;
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/* 11. Estimate the Vertical field frequency:
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*
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* [V FIELD RATE EST] = 1 / [H PERIOD EST] / [TOTAL V LINES] * 1000000
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*/
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v_field_rate_est = 1.0 / h_period_est / total_v_lines * 1000000.0;
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/* 12. Find the actual horizontal period:
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*
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* [H PERIOD] = [H PERIOD EST] / ([V FIELD RATE RQD] / [V FIELD RATE EST])
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*/
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h_period = h_period_est / (v_field_rate_rqd / v_field_rate_est);
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/* 13. Find the actual Vertical field frequency:
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*
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* [V FIELD RATE] = 1 / [H PERIOD] / [TOTAL V LINES] * 1000000
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*/
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v_field_rate = 1.0 / h_period / total_v_lines * 1000000.0;
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/* 14. Find the Vertical frame frequency:
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*
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* [V FRAME RATE] = (IF([INT RQD?]="y", [V FIELD RATE]/2, [V FIELD RATE]))
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*/
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v_frame_rate = interlaced ? v_field_rate / 2.0 : v_field_rate;
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/* 15. Find number of pixels in left margin:
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*
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* [LEFT MARGIN (PIXELS)] = (IF( [MARGINS RQD?]="Y",
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* (ROUND( ([H PIXELS RND] * [MARGIN%] / 100 /
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* [CELL GRAN RND]),0)) * [CELL GRAN RND],
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* 0))
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*/
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left_margin = margins ?
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rint(h_pixels_rnd * MARGIN_PERCENT / 100.0 / CELL_GRAN) * CELL_GRAN :
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0.0;
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/* 16. Find number of pixels in right margin:
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*
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* [RIGHT MARGIN (PIXELS)] = (IF( [MARGINS RQD?]="Y",
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* (ROUND( ([H PIXELS RND] * [MARGIN%] / 100 /
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* [CELL GRAN RND]),0)) * [CELL GRAN RND],
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* 0))
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*/
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right_margin = margins ?
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rint(h_pixels_rnd * MARGIN_PERCENT / 100.0 / CELL_GRAN) * CELL_GRAN :
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0.0;
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/* 17. Find total number of active pixels in image and left and right
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* margins:
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*
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* [TOTAL ACTIVE PIXELS] = [H PIXELS RND] + [LEFT MARGIN (PIXELS)] +
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* [RIGHT MARGIN (PIXELS)]
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*/
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total_active_pixels = h_pixels_rnd + left_margin + right_margin;
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/* 18. Find the ideal blanking duty cycle from the blanking duty cycle
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* equation:
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*
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* [IDEAL DUTY CYCLE] = [C'] - ([M']*[H PERIOD]/1000)
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*/
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ideal_duty_cycle = C_PRIME - (M_PRIME * h_period / 1000.0);
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/* 19. Find the number of pixels in the blanking time to the nearest
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* double character cell:
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*
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* [H BLANK (PIXELS)] = (ROUND(([TOTAL ACTIVE PIXELS] *
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* [IDEAL DUTY CYCLE] /
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* (100-[IDEAL DUTY CYCLE]) /
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* (2*[CELL GRAN RND])), 0))
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* * (2*[CELL GRAN RND])
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*/
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h_blank = rint(total_active_pixels *
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ideal_duty_cycle /
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(100.0 - ideal_duty_cycle) /
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(2.0 * CELL_GRAN)) * (2.0 * CELL_GRAN);
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/* 20. Find total number of pixels:
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*
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* [TOTAL PIXELS] = [TOTAL ACTIVE PIXELS] + [H BLANK (PIXELS)]
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*/
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total_pixels = total_active_pixels + h_blank;
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/* 21. Find pixel clock frequency:
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*
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* [PIXEL FREQ] = [TOTAL PIXELS] / [H PERIOD]
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*/
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pixel_freq = total_pixels / h_period;
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/* 22. Find horizontal frequency:
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*
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* [H FREQ] = 1000 / [H PERIOD]
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*/
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h_freq = 1000.0 / h_period;
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/* Stage 1 computations are now complete; I should really pass
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the results to another function and do the Stage 2
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computations, but I only need a few more values so I'll just
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append the computations here for now */
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/* 17. Find the number of pixels in the horizontal sync period:
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*
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* [H SYNC (PIXELS)] =(ROUND(([H SYNC%] / 100 * [TOTAL PIXELS] /
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* [CELL GRAN RND]),0))*[CELL GRAN RND]
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*/
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h_sync = rint(H_SYNC_PERCENT/100.0 * total_pixels / CELL_GRAN) * CELL_GRAN;
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/* 18. Find the number of pixels in the horizontal front porch period:
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*
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* [H FRONT PORCH (PIXELS)] = ([H BLANK (PIXELS)]/2)-[H SYNC (PIXELS)]
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*/
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h_front_porch = (h_blank / 2.0) - h_sync;
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/* 36. Find the number of lines in the odd front porch period:
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*
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* [V ODD FRONT PORCH(LINES)]=([MIN PORCH RND]+[INTERLACE])
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*/
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v_odd_front_porch_lines = MIN_PORCH + interlace;
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/* finally, pack the results in the mode struct */
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mode->HDisplay = (int) (h_pixels_rnd);
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mode->HSyncStart = (int) (h_pixels_rnd + h_front_porch);
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mode->HSyncEnd = (int) (h_pixels_rnd + h_front_porch + h_sync);
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mode->HTotal = (int) (total_pixels);
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mode->VDisplay = (int) (v_lines_rnd);
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mode->VSyncStart = (int) (v_lines_rnd + v_odd_front_porch_lines);
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mode->VSyncEnd = (int) (v_lines_rnd + v_odd_front_porch_lines + V_SYNC_RQD);
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mode->VTotal = (int) (total_v_lines);
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mode->Clock = (int) (pixel_freq * 1000.0);
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mode->HSync = h_freq;
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mode->VRefresh = freq;
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xf86SetModeDefaultName(mode);
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mode->Flags = V_NHSYNC | V_PVSYNC;
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if (interlaced) {
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mode->VTotal *= 2;
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mode->Flags |= V_INTERLACE;
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}
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return mode;
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}
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