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xserver/hw/xfree86/modes/xf86gtf.c

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/*
* gtf.c Generate mode timings using the GTF Timing Standard
*
* gcc gtf.c -o gtf -lm -Wall
*
* 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
*/
/* Ruthlessly converted to server code by Adam Jackson <ajax@redhat.com> */
#ifdef HAVE_XORG_CONFIG_H
#include <xorg-config.h>
#else
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#endif
#include "xf86.h"
#include "xf86Modes.h"
#include <string.h>
#define MARGIN_PERCENT 1.8 /* % of active vertical image */
#define CELL_GRAN 8.0 /* assumed character cell granularity */
#define MIN_PORCH 1 /* minimum front porch */
#define V_SYNC_RQD 3 /* width of vsync in lines */
#define H_SYNC_PERCENT 8.0 /* width of hsync as % of total line */
#define MIN_VSYNC_PLUS_BP 550.0 /* min time of vsync + back porch (microsec) */
#define M 600.0 /* blanking formula gradient */
#define C 40.0 /* blanking formula offset */
#define K 128.0 /* blanking formula scaling factor */
#define J 20.0 /* blanking formula scaling factor */
/* 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)
/*
* xf86GTFMode() - 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
* XServer of fbset mode descriptions, from what I can tell).
*/
DisplayModePtr
xf86GTFMode(int h_pixels, int v_lines, float freq, int interlaced, int margins)
{
DisplayModeRec *mode = xnfcalloc(1, sizeof(DisplayModeRec));
float h_pixels_rnd;
float v_lines_rnd;
float v_field_rate_rqd;
float top_margin;
float bottom_margin;
float interlace;
float h_period_est;
float vsync_plus_bp;
float v_back_porch;
float total_v_lines;
float v_field_rate_est;
float h_period;
float v_field_rate;
float v_frame_rate;
float left_margin;
float right_margin;
float total_active_pixels;
float ideal_duty_cycle;
float h_blank;
float total_pixels;
float pixel_freq;
float h_freq;
float h_sync;
float h_front_porch;
float v_odd_front_porch_lines;
/* 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_rnd = rint((float) h_pixels / CELL_GRAN) * CELL_GRAN;
/* 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_rnd = interlaced ?
rint((float) v_lines) / 2.0 : rint((float) 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_rate_rqd = interlaced ? (freq * 2.0) : (freq);
/* 4. Find number of lines in Top margin:
*
* [TOP MARGIN (LINES)] = IF([MARGINS RQD?]="Y",
* ROUND(([MARGIN%]/100*[V LINES RND]),0),
* 0)
*/
top_margin = margins ? rint(MARGIN_PERCENT / 100.0 * v_lines_rnd) : (0.0);
/* 5. Find number of lines in Bottom margin:
*
* [BOT MARGIN (LINES)] = IF([MARGINS RQD?]="Y",
* ROUND(([MARGIN%]/100*[V LINES RND]),0),
* 0)
*/
bottom_margin =
margins ? rint(MARGIN_PERCENT / 100.0 * v_lines_rnd) : (0.0);
/* 6. If interlace is required, then set variable [INTERLACE]=0.5:
*
* [INTERLACE]=(IF([INT RQD?]="y",0.5,0))
*/
interlace = interlaced ? 0.5 : 0.0;
/* 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
*/
h_period_est = (((1.0 / v_field_rate_rqd) - (MIN_VSYNC_PLUS_BP / 1000000.0))
/ (v_lines_rnd + (2 * top_margin) + MIN_PORCH + interlace)
* 1000000.0);
/* 8. Find the number of lines in V sync + back porch:
*
* [V SYNC+BP] = ROUND(([MIN VSYNC+BP]/[H PERIOD EST]),0)
*/
vsync_plus_bp = rint(MIN_VSYNC_PLUS_BP / h_period_est);
/* 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 - V_SYNC_RQD;
/* 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_rnd + top_margin + bottom_margin + vsync_plus_bp +
interlace + MIN_PORCH;
/* 11. Estimate the Vertical field frequency:
*
* [V FIELD RATE EST] = 1 / [H PERIOD EST] / [TOTAL V LINES] * 1000000
*/
v_field_rate_est = 1.0 / h_period_est / total_v_lines * 1000000.0;
/* 12. Find the actual horizontal period:
*
* [H PERIOD] = [H PERIOD EST] / ([V FIELD RATE RQD] / [V FIELD RATE EST])
*/
h_period = h_period_est / (v_field_rate_rqd / v_field_rate_est);
/* 13. Find the actual Vertical field frequency:
*
* [V FIELD RATE] = 1 / [H PERIOD] / [TOTAL V LINES] * 1000000
*/
v_field_rate = 1.0 / h_period / total_v_lines * 1000000.0;
/* 14. Find the Vertical frame frequency:
*
* [V FRAME RATE] = (IF([INT RQD?]="y", [V FIELD RATE]/2, [V FIELD RATE]))
*/
v_frame_rate = interlaced ? v_field_rate / 2.0 : v_field_rate;
/* 15. Find number of pixels in left margin:
*
* [LEFT MARGIN (PIXELS)] = (IF( [MARGINS RQD?]="Y",
* (ROUND( ([H PIXELS RND] * [MARGIN%] / 100 /
* [CELL GRAN RND]),0)) * [CELL GRAN RND],
* 0))
*/
left_margin = margins ?
rint(h_pixels_rnd * MARGIN_PERCENT / 100.0 / CELL_GRAN) * CELL_GRAN :
0.0;
/* 16. Find number of pixels in right margin:
*
* [RIGHT MARGIN (PIXELS)] = (IF( [MARGINS RQD?]="Y",
* (ROUND( ([H PIXELS RND] * [MARGIN%] / 100 /
* [CELL GRAN RND]),0)) * [CELL GRAN RND],
* 0))
*/
right_margin = margins ?
rint(h_pixels_rnd * MARGIN_PERCENT / 100.0 / CELL_GRAN) * CELL_GRAN :
0.0;
/* 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_rnd + left_margin + right_margin;
/* 18. Find the ideal blanking duty cycle from the blanking duty cycle
* equation:
*
* [IDEAL DUTY CYCLE] = [C'] - ([M']*[H PERIOD]/1000)
*/
ideal_duty_cycle = C_PRIME - (M_PRIME * h_period / 1000.0);
/* 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])
*/
h_blank = rint(total_active_pixels *
ideal_duty_cycle /
(100.0 - ideal_duty_cycle) /
(2.0 * CELL_GRAN)) * (2.0 * CELL_GRAN);
/* 20. Find total number of pixels:
*
* [TOTAL PIXELS] = [TOTAL ACTIVE PIXELS] + [H BLANK (PIXELS)]
*/
total_pixels = total_active_pixels + h_blank;
/* 21. Find pixel clock frequency:
*
* [PIXEL FREQ] = [TOTAL PIXELS] / [H PERIOD]
*/
pixel_freq = total_pixels / h_period;
/* 22. Find horizontal frequency:
*
* [H FREQ] = 1000 / [H PERIOD]
*/
h_freq = 1000.0 / h_period;
/* 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]
*/
h_sync =
rint(H_SYNC_PERCENT / 100.0 * total_pixels / CELL_GRAN) * CELL_GRAN;
/* 18. Find the number of pixels in the horizontal front porch period:
*
* [H FRONT PORCH (PIXELS)] = ([H BLANK (PIXELS)]/2)-[H SYNC (PIXELS)]
*/
h_front_porch = (h_blank / 2.0) - h_sync;
/* 36. Find the number of lines in the odd front porch period:
*
* [V ODD FRONT PORCH(LINES)]=([MIN PORCH RND]+[INTERLACE])
*/
v_odd_front_porch_lines = MIN_PORCH + interlace;
/* finally, pack the results in the mode struct */
mode->HDisplay = (int) (h_pixels_rnd);
mode->HSyncStart = (int) (h_pixels_rnd + h_front_porch);
mode->HSyncEnd = (int) (h_pixels_rnd + h_front_porch + h_sync);
mode->HTotal = (int) (total_pixels);
mode->VDisplay = (int) (v_lines_rnd);
mode->VSyncStart = (int) (v_lines_rnd + v_odd_front_porch_lines);
mode->VSyncEnd = (int) (v_lines_rnd + v_odd_front_porch_lines + V_SYNC_RQD);
mode->VTotal = (int) (total_v_lines);
mode->Clock = (int) (pixel_freq * 1000.0);
mode->HSync = h_freq;
mode->VRefresh = freq;
xf86SetModeDefaultName(mode);
mode->Flags = V_NHSYNC | V_PVSYNC;
if (interlaced) {
mode->VTotal *= 2;
mode->Flags |= V_INTERLACE;
}
return mode;
}
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