FreeBSD/Linux Kernel Cross Reference
sys/dev/videomode/vesagtf.c

     /* $NetBSD: vesagtf.c,v 1.2 2013/09/15 15:56:07 martin Exp $ */
     /* $FreeBSD$ */
     
     /*-
      * Copyright (c) 2006 Itronix Inc.
      * All rights reserved.
      *
      * Written by Garrett D'Amore for Itronix Inc.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 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.
     * 3. The name of Itronix Inc. may not be used to endorse
     *    or promote products derived from this software without specific
     *    prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY ITRONIX INC. ``AS IS'' AND ANY EXPRESS
     * 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 ITRONIX INC. 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.
     */ 
    
    /*
     * This was derived from a userland GTF program supplied by NVIDIA.
     * NVIDIA's original boilerplate follows. 
     *
     * Note that I have heavily modified the program for use in the EDID
     * kernel code for NetBSD, including removing the use of floating
     * point operations and making significant adjustments to minimize
     * error propagation while operating with integer only math.
     *
     * This has required the use of 64-bit integers in a few places, but
     * the upshot is that for a calculation of 1920x1200x85 (as an
     * example), the error deviates by only ~.004% relative to the
     * floating point version.  This error is *well* within VESA
     * tolerances.
     */
    
    /*
     * Copyright (c) 2001, Andy Ritger  aritger@nvidia.com
     * All rights reserved.
     * 
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 
     * o Redistributions of source code must retain the above copyright
     *   notice, this list of conditions and the following disclaimer.
     * o 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.
     * o Neither the name of NVIDIA nor the names of its contributors
     *   may be used to endorse or promote products derived from this
     *   software without specific prior written permission.
     *
     *
     * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     * "AS IS" AND ANY EXPRESS 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 REGENTS OR 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.
     *
     * 
     *
     * This program is based on the Generalized Timing Formula(GTF TM)
     * Standard Version: 1.0, Revision: 1.0
     *
     * The GTF Document contains the following Copyright information:
     *
     * Copyright (c) 1994, 1995, 1996 - Video Electronics Standards
     * Association. Duplication of this document within VESA member
     * companies for review purposes is permitted. All other rights
     * reserved.
     *
     * While every precaution has been taken in the preparation
     * of this standard, the Video Electronics Standards Association and
     * its contributors assume no responsibility for errors or omissions,
     * and make no warranties, expressed or implied, of functionality
     * of suitability for any purpose. The sample code contained within
    * this standard may be used without restriction.
    *
    * 
    *
    * The GTF EXCEL(TM) SPREADSHEET, a sample (and the definitive)
    * implementation of the GTF Timing Standard, is available at:
    *
    * ftp://ftp.vesa.org/pub/GTF/GTF_V1R1.xls
    *
    *
    *
    * This program takes a desired resolution and vertical refresh rate,
    * and computes mode timings according to the GTF Timing Standard.
    * These mode timings can then be formatted as an XFree86 modeline
    * or a mode description for use by fbset(8).
    *
    *
    *
    * NOTES:
    *
    * The GTF allows for computation of "margins" (the visible border
    * surrounding the addressable video); on most non-overscan type
    * systems, the margin period is zero.  I've implemented the margin
    * computations but not enabled it because 1) I don't really have
    * any experience with this, and 2) neither XFree86 modelines nor
    * fbset fb.modes provide an obvious way for margin timings to be
    * included in their mode descriptions (needs more investigation).
    * 
    * The GTF provides for computation of interlaced mode timings;
    * I've implemented the computations but not enabled them, yet.
    * I should probably enable and test this at some point.
    *
    * 
    *
    * TODO:
    *
    * o Add support for interlaced modes.
    *
    * o Implement the other portions of the GTF: compute mode timings
    *   given either the desired pixel clock or the desired horizontal
    *   frequency.
    *
    * o It would be nice if this were more general purpose to do things
    *   outside the scope of the GTF: like generate double scan mode
    *   timings, for example.
    *   
    * o Printing digits to the right of the decimal point when the
    *   digits are 0 annoys me.
    *
    * o Error checking.
    *
    */
   
   #ifdef  _KERNEL
   #include <sys/cdefs.h>
   
   __FBSDID("$FreeBSD$");
   #include <sys/types.h>
   #include <sys/param.h>
   #include <sys/systm.h>
   #include <dev/videomode/videomode.h>
   #include <dev/videomode/vesagtf.h>
   #else
   #include <stdio.h>
   #include <stdlib.h>
   #include <sys/types.h>
   #include "videomode.h"
   #include "vesagtf.h"
   
   void print_xf86_mode(struct videomode *m);
   #endif
   
   #define CELL_GRAN         8     /* assumed character cell granularity        */
   
   /* C' and M' are part of the Blanking Duty Cycle computation */
   /*
    * #define C_PRIME           (((C - J) * K/256.0) + J)
    * #define M_PRIME           (K/256.0 * M)
    */
   
   /*
    * C' and M' multiplied by 256 to give integer math.  Make sure to
    * scale results using these back down, appropriately.
    */
   #define C_PRIME256(p)     (((p->C - p->J) * p->K) + (p->J * 256))
   #define M_PRIME256(p)     (p->K * p->M)
   
   #define DIVIDE(x,y)     (((x) + ((y) / 2)) / (y))
   
   /*
    * print_value() - print the result of the named computation; this is
    * useful when comparing against the GTF EXCEL spreadsheet.
    */
   
   #ifdef GTFDEBUG
   
   static void
   print_value(int n, const char *name, unsigned val)
   {
           printf("%2d: %-27s: %u\n", n, name, val);
   }
   #else
   #define print_value(n, name, val)
   #endif
   
   /*
    * vert_refresh() - as defined by the GTF Timing Standard, compute the
    * Stage 1 Parameters using the vertical refresh frequency.  In other
    * words: input a desired resolution and desired refresh rate, and
    * output the GTF mode timings.
    *
    * XXX All the code is in place to compute interlaced modes, but I don't
    * feel like testing it right now.
    *
    * XXX margin computations are implemented but not tested (nor used by
    * XFree86 of fbset mode descriptions, from what I can tell).
    */
   
   void
   vesagtf_mode_params(unsigned h_pixels, unsigned v_lines, unsigned freq,
       struct vesagtf_params *params, int flags, struct videomode *vmp)
   {
       unsigned v_field_rqd;
       unsigned top_margin;
       unsigned bottom_margin;
       unsigned interlace;
       uint64_t h_period_est;
       unsigned vsync_plus_bp;
       unsigned v_back_porch __unused;
       unsigned total_v_lines;
       uint64_t v_field_est;
       uint64_t h_period;
       unsigned v_field_rate;
       unsigned v_frame_rate __unused;
       unsigned left_margin;
       unsigned right_margin;
       unsigned total_active_pixels;
       uint64_t ideal_duty_cycle;
       unsigned h_blank;
       unsigned total_pixels;
       unsigned pixel_freq;
   
       unsigned h_sync;
       unsigned h_front_porch;
       unsigned v_odd_front_porch_lines;
   
   #ifdef  GTFDEBUG
       unsigned h_freq;
   #endif
       
       /*  1. In order to give correct results, the number of horizontal
        *  pixels requested is first processed to ensure that it is divisible
        *  by the character size, by rounding it to the nearest character
        *  cell boundary:
        *
        *  [H PIXELS RND] = ((ROUND([H PIXELS]/[CELL GRAN RND],0))*[CELLGRAN RND])
        */
       
       h_pixels = DIVIDE(h_pixels, CELL_GRAN) * CELL_GRAN;
       
       print_value(1, "[H PIXELS RND]", h_pixels);
   
       
       /*  2. If interlace is requested, the number of vertical lines assumed
        *  by the calculation must be halved, as the computation calculates
        *  the number of vertical lines per field. In either case, the
        *  number of lines is rounded to the nearest integer.
        *   
        *  [V LINES RND] = IF([INT RQD?]="y", ROUND([V LINES]/2,0),
        *                                     ROUND([V LINES],0))
        */
   
       v_lines = (flags & VESAGTF_FLAG_ILACE) ? DIVIDE(v_lines, 2) : v_lines;
       
       print_value(2, "[V LINES RND]", v_lines);
       
       
       /*  3. Find the frame rate required:
        *
        *  [V FIELD RATE RQD] = IF([INT RQD?]="y", [I/P FREQ RQD]*2,
        *                                          [I/P FREQ RQD])
        */
   
       v_field_rqd = (flags & VESAGTF_FLAG_ILACE) ? (freq * 2) : (freq);
   
       print_value(3, "[V FIELD RATE RQD]", v_field_rqd);
       
   
       /*  4. Find number of lines in Top margin:
        *  5. Find number of lines in Bottom margin:
        *
        *  [TOP MARGIN (LINES)] = IF([MARGINS RQD?]="Y",
        *          ROUND(([MARGIN%]/100*[V LINES RND]),0),
        *          0)
        *
        *  Ditto for bottom margin.  Note that instead of %, we use PPT, which
        *  is parts per thousand.  This helps us with integer math.
        */
   
       top_margin = bottom_margin = (flags & VESAGTF_FLAG_MARGINS) ?
           DIVIDE(v_lines * params->margin_ppt, 1000) : 0;
   
       print_value(4, "[TOP MARGIN (LINES)]", top_margin);
       print_value(5, "[BOT MARGIN (LINES)]", bottom_margin);
   
       
       /*  6. If interlace is required, then set variable [INTERLACE]=0.5:
        *   
        *  [INTERLACE]=(IF([INT RQD?]="y",0.5,0))
        *
        *  To make this integer friendly, we use some special hacks in step
        *  7 below.  Please read those comments to understand why I am using
        *  a whole number of 1.0 instead of 0.5 here.
        */
       interlace = (flags & VESAGTF_FLAG_ILACE) ? 1 : 0;
   
       print_value(6, "[2*INTERLACE]", interlace);
       
   
       /*  7. Estimate the Horizontal period
        *
        *  [H PERIOD EST] = ((1/[V FIELD RATE RQD]) - [MIN VSYNC+BP]/1000000) /
        *                    ([V LINES RND] + (2*[TOP MARGIN (LINES)]) +
        *                     [MIN PORCH RND]+[INTERLACE]) * 1000000
        *
        *  To make it integer friendly, we pre-multiply the 1000000 to get to
        *  usec.  This gives us:
        *
        *  [H PERIOD EST] = ((1000000/[V FIELD RATE RQD]) - [MIN VSYNC+BP]) /
        *                  ([V LINES RND] + (2 * [TOP MARGIN (LINES)]) +
        *                   [MIN PORCH RND]+[INTERLACE])
        *
        *  The other problem is that the interlace value is wrong.  To get
        *  the interlace to a whole number, we multiply both the numerator and
        *  divisor by 2, so we can use a value of either 1 or 0 for the interlace
        *  factor.
        *
        * This gives us:
        *
        * [H PERIOD EST] = ((2*((1000000/[V FIELD RATE RQD]) - [MIN VSYNC+BP])) /
        *                   (2*([V LINES RND] + (2*[TOP MARGIN (LINES)]) +
        *                    [MIN PORCH RND]) + [2*INTERLACE]))
        *
        * Finally we multiply by another 1000, to get value in picosec.
        * Why picosec?  To minimize rounding errors.  Gotta love integer
        * math and error propagation.
        */
   
       h_period_est = DIVIDE(((DIVIDE(2000000000000ULL, v_field_rqd)) -
                                 (2000000 * params->min_vsbp)),
           ((2 * (v_lines + (2 * top_margin) + params->min_porch)) + interlace));
   
       print_value(7, "[H PERIOD EST (ps)]", h_period_est);
       
   
       /*  8. Find the number of lines in V sync + back porch:
        *
        *  [V SYNC+BP] = ROUND(([MIN VSYNC+BP]/[H PERIOD EST]),0)
        *
        *  But recall that h_period_est is in psec. So multiply by 1000000.
        */
   
       vsync_plus_bp = DIVIDE(params->min_vsbp * 1000000, h_period_est);
   
       print_value(8, "[V SYNC+BP]", vsync_plus_bp);
       
       
       /*  9. Find the number of lines in V back porch alone:
        *
        *  [V BACK PORCH] = [V SYNC+BP] - [V SYNC RND]
        *
        *  XXX is "[V SYNC RND]" a typo? should be [V SYNC RQD]?
        */
       
       v_back_porch = vsync_plus_bp - params->vsync_rqd;
       
       print_value(9, "[V BACK PORCH]", v_back_porch);
       
   
       /*  10. Find the total number of lines in Vertical field period:
        *
        *  [TOTAL V LINES] = [V LINES RND] + [TOP MARGIN (LINES)] +
        *                    [BOT MARGIN (LINES)] + [V SYNC+BP] + [INTERLACE] +
        *                    [MIN PORCH RND]
        */
   
       total_v_lines = v_lines + top_margin + bottom_margin + vsync_plus_bp +
           interlace + params->min_porch;
       
       print_value(10, "[TOTAL V LINES]", total_v_lines);
       
   
       /*  11. Estimate the Vertical field frequency:
        *
        *  [V FIELD RATE EST] = 1 / [H PERIOD EST] / [TOTAL V LINES] * 1000000
        *
        *  Again, we want to pre multiply by 10^9 to convert for nsec, thereby
        *  making it usable in integer math.
        *
        *  So we get:
        *
        *  [V FIELD RATE EST] = 1000000000 / [H PERIOD EST] / [TOTAL V LINES]
        *
        *  This is all scaled to get the result in uHz.  Again, we're trying to
        *  minimize error propagation.
        */
       v_field_est = DIVIDE(DIVIDE(1000000000000000ULL, h_period_est),
           total_v_lines);
       
       print_value(11, "[V FIELD RATE EST(uHz)]", v_field_est);
       
   
       /*  12. Find the actual horizontal period:
        *
        *  [H PERIOD] = [H PERIOD EST] / ([V FIELD RATE RQD] / [V FIELD RATE EST])
        */
   
       h_period = DIVIDE(h_period_est * v_field_est, v_field_rqd * 1000);
       
       print_value(12, "[H PERIOD(ps)]", h_period);
       
   
       /*  13. Find the actual Vertical field frequency:
        *
        *  [V FIELD RATE] = 1 / [H PERIOD] / [TOTAL V LINES] * 1000000
        *
        *  And again, we convert to nsec ahead of time, giving us:
        *
        *  [V FIELD RATE] = 1000000 / [H PERIOD] / [TOTAL V LINES]
        *
        *  And another rescaling back to mHz.  Gotta love it.
        */
   
       v_field_rate = DIVIDE(1000000000000ULL, h_period * total_v_lines);
   
       print_value(13, "[V FIELD RATE]", v_field_rate);
       
   
       /*  14. Find the Vertical frame frequency:
        *
        *  [V FRAME RATE] = (IF([INT RQD?]="y", [V FIELD RATE]/2, [V FIELD RATE]))
        *
        *  N.B. that the result here is in mHz.
        */
   
       v_frame_rate = (flags & VESAGTF_FLAG_ILACE) ?
           v_field_rate / 2 : v_field_rate;
   
       print_value(14, "[V FRAME RATE]", v_frame_rate);
       
   
       /*  15. Find number of pixels in left margin:
        *  16. Find number of pixels in right margin:
        *
        *  [LEFT MARGIN (PIXELS)] = (IF( [MARGINS RQD?]="Y",
        *          (ROUND( ([H PIXELS RND] * [MARGIN%] / 100 /
        *                   [CELL GRAN RND]),0)) * [CELL GRAN RND],
        *          0))
        *
        *  Again, we deal with margin percentages as PPT (parts per thousand).
        *  And the calculations for left and right are the same.
        */
   
       left_margin = right_margin = (flags & VESAGTF_FLAG_MARGINS) ?
           DIVIDE(DIVIDE(h_pixels * params->margin_ppt, 1000),
               CELL_GRAN) * CELL_GRAN : 0;
   
       print_value(15, "[LEFT MARGIN (PIXELS)]", left_margin);
       print_value(16, "[RIGHT MARGIN (PIXELS)]", right_margin);
       
   
       /*  17. Find total number of active pixels in image and left and right
        *  margins:
        *
        *  [TOTAL ACTIVE PIXELS] = [H PIXELS RND] + [LEFT MARGIN (PIXELS)] +
        *                          [RIGHT MARGIN (PIXELS)]
        */
   
       total_active_pixels = h_pixels + left_margin + right_margin;
       
       print_value(17, "[TOTAL ACTIVE PIXELS]", total_active_pixels);
       
       
       /*  18. Find the ideal blanking duty cycle from the blanking duty cycle
        *  equation:
        *
        *  [IDEAL DUTY CYCLE] = [C'] - ([M']*[H PERIOD]/1000)
        *
        *  However, we have modified values for [C'] as [256*C'] and
        *  [M'] as [256*M'].  Again the idea here is to get good scaling.
        *  We use 256 as the factor to make the math fast.
        *
        *  Note that this means that we have to scale it appropriately in
        *  later calculations.
        *
        *  The ending result is that our ideal_duty_cycle is 256000x larger
        *  than the duty cycle used by VESA.  But again, this reduces error
        *  propagation.
        */
   
       ideal_duty_cycle =
           ((C_PRIME256(params) * 1000) -
               (M_PRIME256(params) * h_period / 1000000));
       
       print_value(18, "[IDEAL DUTY CYCLE]", ideal_duty_cycle);
       
   
       /*  19. Find the number of pixels in the blanking time to the nearest
        *  double character cell:
        *
        *  [H BLANK (PIXELS)] = (ROUND(([TOTAL ACTIVE PIXELS] *
        *                               [IDEAL DUTY CYCLE] /
        *                               (100-[IDEAL DUTY CYCLE]) /
        *                               (2*[CELL GRAN RND])), 0))
        *                       * (2*[CELL GRAN RND])
        *
        *  Of course, we adjust to make this rounding work in integer math.
        */
   
       h_blank = DIVIDE(DIVIDE(total_active_pixels * ideal_duty_cycle,
                            (256000 * 100ULL) - ideal_duty_cycle),
           2 * CELL_GRAN) * (2 * CELL_GRAN);
   
       print_value(19, "[H BLANK (PIXELS)]", h_blank);
       
   
       /*  20. Find total number of pixels:
        *
        *  [TOTAL PIXELS] = [TOTAL ACTIVE PIXELS] + [H BLANK (PIXELS)]
        */
   
       total_pixels = total_active_pixels + h_blank;
       
       print_value(20, "[TOTAL PIXELS]", total_pixels);
       
   
       /*  21. Find pixel clock frequency:
        *
        *  [PIXEL FREQ] = [TOTAL PIXELS] / [H PERIOD]
        *
        *  We calculate this in Hz rather than MHz, to get a value that
        *  is usable with integer math.  Recall that the [H PERIOD] is in
        *  nsec.
        */
       
       pixel_freq = DIVIDE(total_pixels * 1000000, DIVIDE(h_period, 1000));
       
       print_value(21, "[PIXEL FREQ]", pixel_freq);
       
   
       /*  22. Find horizontal frequency:
        *
        *  [H FREQ] = 1000 / [H PERIOD]
        *
        *  I've ifdef'd this out, because we don't need it for any of
        *  our calculations.
        *  We calculate this in Hz rather than kHz, to avoid rounding
        *  errors.  Recall that the [H PERIOD] is in usec.
        */
   
   #ifdef  GTFDEBUG
       h_freq = 1000000000 / h_period;
       
       print_value(22, "[H FREQ]", h_freq);
   #endif
       
   
       /* Stage 1 computations are now complete; I should really pass
          the results to another function and do the Stage 2
          computations, but I only need a few more values so I'll just
          append the computations here for now */
   
       
   
       /*  17. Find the number of pixels in the horizontal sync period:
        *
        *  [H SYNC (PIXELS)] =(ROUND(([H SYNC%] / 100 * [TOTAL PIXELS] /
        *                             [CELL GRAN RND]),0))*[CELL GRAN RND]
        *
        *  Rewriting for integer math:
        *
        *  [H SYNC (PIXELS)]=(ROUND((H SYNC%] * [TOTAL PIXELS] / 100 /
        *                             [CELL GRAN RND),0))*[CELL GRAN RND]
        */
   
       h_sync = DIVIDE(((params->hsync_pct * total_pixels) / 100), CELL_GRAN) *
           CELL_GRAN;
   
       print_value(17, "[H SYNC (PIXELS)]", h_sync);
       
   
       /*  18. Find the number of pixels in the horizontal front porch period:
        *
        *  [H FRONT PORCH (PIXELS)] = ([H BLANK (PIXELS)]/2)-[H SYNC (PIXELS)]
        *
        *  Note that h_blank is always an even number of characters (i.e.
        *  h_blank % (CELL_GRAN * 2) == 0)
        */
   
       h_front_porch = (h_blank / 2) - h_sync;
   
       print_value(18, "[H FRONT PORCH (PIXELS)]", h_front_porch);
       
       
       /*  36. Find the number of lines in the odd front porch period:
        *
        *  [V ODD FRONT PORCH(LINES)]=([MIN PORCH RND]+[INTERLACE])
        *
        *  Adjusting for the fact that the interlace is scaled:
        *
        *  [V ODD FRONT PORCH(LINES)]=(([MIN PORCH RND] * 2) + [2*INTERLACE]) / 2
        */
       
       v_odd_front_porch_lines = ((2 * params->min_porch) + interlace) / 2;
       
       print_value(36, "[V ODD FRONT PORCH(LINES)]", v_odd_front_porch_lines);
       
   
       /* finally, pack the results in the mode struct */
   
       vmp->hsync_start = h_pixels + h_front_porch;
       vmp->hsync_end = vmp->hsync_start + h_sync;
       vmp->htotal = total_pixels;
       vmp->hdisplay = h_pixels;
   
       vmp->vsync_start = v_lines + v_odd_front_porch_lines;
       vmp->vsync_end = vmp->vsync_start + params->vsync_rqd;
       vmp->vtotal = total_v_lines;
       vmp->vdisplay = v_lines;
   
       vmp->dot_clock = pixel_freq;
       
   }
   
   void
   vesagtf_mode(unsigned x, unsigned y, unsigned refresh, struct videomode *vmp)
   {
           struct vesagtf_params   params;
   
           params.margin_ppt = VESAGTF_MARGIN_PPT;
           params.min_porch = VESAGTF_MIN_PORCH;
           params.vsync_rqd = VESAGTF_VSYNC_RQD;
           params.hsync_pct = VESAGTF_HSYNC_PCT;
           params.min_vsbp = VESAGTF_MIN_VSBP;
           params.M = VESAGTF_M;
           params.C = VESAGTF_C;
           params.K = VESAGTF_K;
           params.J = VESAGTF_J;
   
           vesagtf_mode_params(x, y, refresh, &params, 0, vmp);
   }
   
   /*
    * The tidbit here is so that you can compile this file as a
    * standalone user program to generate X11 modelines using VESA GTF.
    * This also allows for testing of the code itself, without
    * necessitating a full kernel recompile.
    */
   
   /* print_xf86_mode() - print the XFree86 modeline, given mode timings. */
   
   #ifndef _KERNEL
   void
   print_xf86_mode (struct videomode *vmp)
   {
           float   vf, hf;
   
           hf = 1000.0 * vmp->dot_clock / vmp->htotal;
           vf = 1.0 * hf / vmp->vtotal;
   
       printf("\n");
       printf("  # %dx%d @ %.2f Hz (GTF) hsync: %.2f kHz; pclk: %.2f MHz\n",
           vmp->hdisplay, vmp->vdisplay, vf, hf, vmp->dot_clock / 1000.0);
       
       printf("  Modeline \"%dx%d_%.2f\"  %.2f"
           "  %d %d %d %d"
           "  %d %d %d %d"
           "  -HSync +Vsync\n\n",
           vmp->hdisplay, vmp->vdisplay, vf, (vmp->dot_clock / 1000.0),
           vmp->hdisplay, vmp->hsync_start, vmp->hsync_end, vmp->htotal,
           vmp->vdisplay, vmp->vsync_start, vmp->vsync_end, vmp->vtotal);
   }
   
   int
   main (int argc, char *argv[])
   {
           struct videomode m;
   
           if (argc != 4) {
                   printf("usage: %s x y refresh\n", argv[0]);
                   exit(1);
           }
       
           vesagtf_mode(atoi(argv[1]), atoi(argv[2]), atoi(argv[3]), &m);
   
           print_xf86_mode(&m);
       
           return 0;
       
   }
   #endif

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