[deb_xorg-server.git] / hw / xfree86 / modes / xf86gtf.c

/*
 * 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;
}
Commit	Line	Data
a09e091a JB	1	/*
	2	* gtf.c Generate mode timings using the GTF Timing Standard
	3	*
	4	* gcc gtf.c -o gtf -lm -Wall
	5	*
	6	* Copyright (c) 2001, Andy Ritger aritger@nvidia.com
	7	* All rights reserved.
	8	*
	9	* Redistribution and use in source and binary forms, with or without
	10	* modification, are permitted provided that the following conditions
	11	* are met:
	12	*
	13	* o Redistributions of source code must retain the above copyright
	14	* notice, this list of conditions and the following disclaimer.
	15	* o Redistributions in binary form must reproduce the above copyright
	16	* notice, this list of conditions and the following disclaimer
	17	* in the documentation and/or other materials provided with the
	18	* distribution.
	19	* o Neither the name of NVIDIA nor the names of its contributors
	20	* may be used to endorse or promote products derived from this
	21	* software without specific prior written permission.
	22	*
	23	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	24	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
	25	* NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
	26	* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
	27	* THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
	28	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
	29	* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	30	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
	31	* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	32	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
	33	* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	34	* POSSIBILITY OF SUCH DAMAGE.
	35	*
	36	* This program is based on the Generalized Timing Formula(GTF TM)
	37	* Standard Version: 1.0, Revision: 1.0
	38	*
	39	* The GTF Document contains the following Copyright information:
	40	*
	41	* Copyright (c) 1994, 1995, 1996 - Video Electronics Standards
	42	* Association. Duplication of this document within VESA member
	43	* companies for review purposes is permitted. All other rights
	44	* reserved.
	45	*
	46	* While every precaution has been taken in the preparation
	47	* of this standard, the Video Electronics Standards Association and
	48	* its contributors assume no responsibility for errors or omissions,
	49	* and make no warranties, expressed or implied, of functionality
	50	* of suitability for any purpose. The sample code contained within
	51	* this standard may be used without restriction.
	52	*
	53	*
	54	*
	55	* The GTF EXCEL(TM) SPREADSHEET, a sample (and the definitive)
	56	* implementation of the GTF Timing Standard, is available at:
	57	*
	58	* ftp://ftp.vesa.org/pub/GTF/GTF_V1R1.xls
	59	*/
	60
	61	/* Ruthlessly converted to server code by Adam Jackson <ajax@redhat.com> */
	62
	63	#ifdef HAVE_XORG_CONFIG_H
	64	#include <xorg-config.h>
65	#else
66	#ifdef HAVE_CONFIG_H
67	#include <config.h>
68	#endif
69	#endif
70
71	#include "xf86.h"
72	#include "xf86Modes.h"
73	#include <string.h>
74
75	#define MARGIN_PERCENT 1.8 /* % of active vertical image */
76	#define CELL_GRAN 8.0 /* assumed character cell granularity */
77	#define MIN_PORCH 1 /* minimum front porch */
78	#define V_SYNC_RQD 3 /* width of vsync in lines */
79	#define H_SYNC_PERCENT 8.0 /* width of hsync as % of total line */
80	#define MIN_VSYNC_PLUS_BP 550.0 /* min time of vsync + back porch (microsec) */
81	#define M 600.0 /* blanking formula gradient */
82	#define C 40.0 /* blanking formula offset */
83	#define K 128.0 /* blanking formula scaling factor */
84	#define J 20.0 /* blanking formula scaling factor */
85
86	/* C' and M' are part of the Blanking Duty Cycle computation */
87
88	#define C_PRIME (((C - J) * K/256.0) + J)
89	#define M_PRIME (K/256.0 * M)
90
91	/*
92	* xf86GTFMode() - as defined by the GTF Timing Standard, compute the
93	* Stage 1 Parameters using the vertical refresh frequency. In other
94	* words: input a desired resolution and desired refresh rate, and
95	* output the GTF mode timings.
96	*
97	* XXX All the code is in place to compute interlaced modes, but I don't
98	* feel like testing it right now.
99	*
100	* XXX margin computations are implemented but not tested (nor used by
101	* XServer of fbset mode descriptions, from what I can tell).
102	*/
103
104	DisplayModePtr
105	xf86GTFMode(int h_pixels, int v_lines, float freq, int interlaced, int margins)
106	{
107	DisplayModeRec *mode = xnfcalloc(1, sizeof(DisplayModeRec));
108
109	float h_pixels_rnd;
110	float v_lines_rnd;
111	float v_field_rate_rqd;
112	float top_margin;
113	float bottom_margin;
114	float interlace;
115	float h_period_est;
116	float vsync_plus_bp;
117	float v_back_porch;
118	float total_v_lines;
119	float v_field_rate_est;
120	float h_period;
121	float v_field_rate;
122	float v_frame_rate;
123	float left_margin;
124	float right_margin;
125	float total_active_pixels;
126	float ideal_duty_cycle;
127	float h_blank;
128	float total_pixels;
129	float pixel_freq;
130	float h_freq;
131
132	float h_sync;
133	float h_front_porch;
134	float v_odd_front_porch_lines;
135
136	/* 1. In order to give correct results, the number of horizontal
137	* pixels requested is first processed to ensure that it is divisible
138	* by the character size, by rounding it to the nearest character
139	* cell boundary:
140	*
141	* [H PIXELS RND] = ((ROUND([H PIXELS]/[CELL GRAN RND],0))*[CELLGRAN RND])
142	*/
143
144	h_pixels_rnd = rint((float) h_pixels / CELL_GRAN) * CELL_GRAN;
145
146	/* 2. If interlace is requested, the number of vertical lines assumed
147	* by the calculation must be halved, as the computation calculates
148	* the number of vertical lines per field. In either case, the
149	* number of lines is rounded to the nearest integer.
150	*
151	* [V LINES RND] = IF([INT RQD?]="y", ROUND([V LINES]/2,0),
152	* ROUND([V LINES],0))
153	*/
154
155	v_lines_rnd = interlaced ?
156	rint((float) v_lines) / 2.0 : rint((float) v_lines);
157
158	/* 3. Find the frame rate required:
159	*
160	* [V FIELD RATE RQD] = IF([INT RQD?]="y", [I/P FREQ RQD]*2,
161	* [I/P FREQ RQD])
162	*/
163
164	v_field_rate_rqd = interlaced ? (freq * 2.0) : (freq);
165
166	/* 4. Find number of lines in Top margin:
167	*
168	* [TOP MARGIN (LINES)] = IF([MARGINS RQD?]="Y",
169	* ROUND(([MARGIN%]/100*[V LINES RND]),0),
170	* 0)
171	*/
172
173	top_margin = margins ? rint(MARGIN_PERCENT / 100.0 * v_lines_rnd) : (0.0);
174
175	/* 5. Find number of lines in Bottom margin:
176	*
177	* [BOT MARGIN (LINES)] = IF([MARGINS RQD?]="Y",
178	* ROUND(([MARGIN%]/100*[V LINES RND]),0),
179	* 0)
180	*/
181
182	bottom_margin =
183	margins ? rint(MARGIN_PERCENT / 100.0 * v_lines_rnd) : (0.0);
184
185	/* 6. If interlace is required, then set variable [INTERLACE]=0.5:
186	*
187	* [INTERLACE]=(IF([INT RQD?]="y",0.5,0))
188	*/
189
190	interlace = interlaced ? 0.5 : 0.0;
191
192	/* 7. Estimate the Horizontal period
193	*
194	* [H PERIOD EST] = ((1/[V FIELD RATE RQD]) - [MIN VSYNC+BP]/1000000) /
195	* ([V LINES RND] + (2*[TOP MARGIN (LINES)]) +
196	* [MIN PORCH RND]+[INTERLACE]) * 1000000
197	*/
198
199	h_period_est = (((1.0 / v_field_rate_rqd) - (MIN_VSYNC_PLUS_BP / 1000000.0))
200	/ (v_lines_rnd + (2 * top_margin) + MIN_PORCH + interlace)
201	* 1000000.0);
202
203	/* 8. Find the number of lines in V sync + back porch:
204	*
205	* [V SYNC+BP] = ROUND(([MIN VSYNC+BP]/[H PERIOD EST]),0)
206	*/
207
208	vsync_plus_bp = rint(MIN_VSYNC_PLUS_BP / h_period_est);
209
210	/* 9. Find the number of lines in V back porch alone:
211	*
212	* [V BACK PORCH] = [V SYNC+BP] - [V SYNC RND]
213	*
214	* XXX is "[V SYNC RND]" a typo? should be [V SYNC RQD]?
215	*/
216
217	v_back_porch = vsync_plus_bp - V_SYNC_RQD;
218
219	/* 10. Find the total number of lines in Vertical field period:
220	*
221	* [TOTAL V LINES] = [V LINES RND] + [TOP MARGIN (LINES)] +
222	* [BOT MARGIN (LINES)] + [V SYNC+BP] + [INTERLACE] +
223	* [MIN PORCH RND]
224	*/
225
226	total_v_lines = v_lines_rnd + top_margin + bottom_margin + vsync_plus_bp +
227	interlace + MIN_PORCH;
228
229	/* 11. Estimate the Vertical field frequency:
230	*
231	* [V FIELD RATE EST] = 1 / [H PERIOD EST] / [TOTAL V LINES] * 1000000
232	*/
233
234	v_field_rate_est = 1.0 / h_period_est / total_v_lines * 1000000.0;
235
236	/* 12. Find the actual horizontal period:
237	*
238	* [H PERIOD] = [H PERIOD EST] / ([V FIELD RATE RQD] / [V FIELD RATE EST])
239	*/
240
241	h_period = h_period_est / (v_field_rate_rqd / v_field_rate_est);
242
243	/* 13. Find the actual Vertical field frequency:
244	*
245	* [V FIELD RATE] = 1 / [H PERIOD] / [TOTAL V LINES] * 1000000
246	*/
247
248	v_field_rate = 1.0 / h_period / total_v_lines * 1000000.0;
249
250	/* 14. Find the Vertical frame frequency:
251	*
252	* [V FRAME RATE] = (IF([INT RQD?]="y", [V FIELD RATE]/2, [V FIELD RATE]))
253	*/
254
255	v_frame_rate = interlaced ? v_field_rate / 2.0 : v_field_rate;
256
257	/* 15. Find number of pixels in left margin:
258	*
259	* [LEFT MARGIN (PIXELS)] = (IF( [MARGINS RQD?]="Y",
260	* (ROUND( ([H PIXELS RND] * [MARGIN%] / 100 /
261	* [CELL GRAN RND]),0)) * [CELL GRAN RND],
262	* 0))
263	*/
264
265	left_margin = margins ?
266	rint(h_pixels_rnd * MARGIN_PERCENT / 100.0 / CELL_GRAN) * CELL_GRAN :
267	0.0;
268
269	/* 16. Find number of pixels in right margin:
270	*
271	* [RIGHT MARGIN (PIXELS)] = (IF( [MARGINS RQD?]="Y",
272	* (ROUND( ([H PIXELS RND] * [MARGIN%] / 100 /
273	* [CELL GRAN RND]),0)) * [CELL GRAN RND],
274	* 0))
275	*/
276
277	right_margin = margins ?
278	rint(h_pixels_rnd * MARGIN_PERCENT / 100.0 / CELL_GRAN) * CELL_GRAN :
279	0.0;
280
281	/* 17. Find total number of active pixels in image and left and right
282	* margins:
283	*
284	* [TOTAL ACTIVE PIXELS] = [H PIXELS RND] + [LEFT MARGIN (PIXELS)] +
285	* [RIGHT MARGIN (PIXELS)]
286	*/
287
288	total_active_pixels = h_pixels_rnd + left_margin + right_margin;
289
290	/* 18. Find the ideal blanking duty cycle from the blanking duty cycle
291	* equation:
292	*
293	* [IDEAL DUTY CYCLE] = [C'] - ([M']*[H PERIOD]/1000)
294	*/
295
296	ideal_duty_cycle = C_PRIME - (M_PRIME * h_period / 1000.0);
297
298	/* 19. Find the number of pixels in the blanking time to the nearest
299	* double character cell:
300	*
301	* [H BLANK (PIXELS)] = (ROUND(([TOTAL ACTIVE PIXELS] *
302	* [IDEAL DUTY CYCLE] /
303	* (100-[IDEAL DUTY CYCLE]) /
304	* (2*[CELL GRAN RND])), 0))
305	* * (2*[CELL GRAN RND])
306	*/
307
308	h_blank = rint(total_active_pixels *
309	ideal_duty_cycle /
310	(100.0 - ideal_duty_cycle) /
311	(2.0 * CELL_GRAN)) * (2.0 * CELL_GRAN);
312
313	/* 20. Find total number of pixels:
314	*
315	* [TOTAL PIXELS] = [TOTAL ACTIVE PIXELS] + [H BLANK (PIXELS)]
316	*/
317
318	total_pixels = total_active_pixels + h_blank;
319
320	/* 21. Find pixel clock frequency:
321	*
322	* [PIXEL FREQ] = [TOTAL PIXELS] / [H PERIOD]
323	*/
324
325	pixel_freq = total_pixels / h_period;
326
327	/* 22. Find horizontal frequency:
328	*
329	* [H FREQ] = 1000 / [H PERIOD]
330	*/
331
332	h_freq = 1000.0 / h_period;
333
334	/* Stage 1 computations are now complete; I should really pass
335	the results to another function and do the Stage 2
336	computations, but I only need a few more values so I'll just
337	append the computations here for now */
338
339	/* 17. Find the number of pixels in the horizontal sync period:
340	*
341	* [H SYNC (PIXELS)] =(ROUND(([H SYNC%] / 100 * [TOTAL PIXELS] /
342	* [CELL GRAN RND]),0))*[CELL GRAN RND]
343	*/
344
345	h_sync =
346	rint(H_SYNC_PERCENT / 100.0 * total_pixels / CELL_GRAN) * CELL_GRAN;
347
348	/* 18. Find the number of pixels in the horizontal front porch period:
349	*
350	* [H FRONT PORCH (PIXELS)] = ([H BLANK (PIXELS)]/2)-[H SYNC (PIXELS)]
351	*/
352
353	h_front_porch = (h_blank / 2.0) - h_sync;
354
355	/* 36. Find the number of lines in the odd front porch period:
356	*
357	* [V ODD FRONT PORCH(LINES)]=([MIN PORCH RND]+[INTERLACE])
358	*/
359
360	v_odd_front_porch_lines = MIN_PORCH + interlace;
361
362	/* finally, pack the results in the mode struct */
363
364	mode->HDisplay = (int) (h_pixels_rnd);
365	mode->HSyncStart = (int) (h_pixels_rnd + h_front_porch);
366	mode->HSyncEnd = (int) (h_pixels_rnd + h_front_porch + h_sync);
367	mode->HTotal = (int) (total_pixels);
368	mode->VDisplay = (int) (v_lines_rnd);
369	mode->VSyncStart = (int) (v_lines_rnd + v_odd_front_porch_lines);
370	mode->VSyncEnd = (int) (v_lines_rnd + v_odd_front_porch_lines + V_SYNC_RQD);
371	mode->VTotal = (int) (total_v_lines);
372
373	mode->Clock = (int) (pixel_freq * 1000.0);
374	mode->HSync = h_freq;
375	mode->VRefresh = freq;
376
377	xf86SetModeDefaultName(mode);
378
379	mode->Flags = V_NHSYNC \| V_PVSYNC;
380	if (interlaced) {
381	mode->VTotal *= 2;
382	mode->Flags \|= V_INTERLACE;
383	}
384
385	return mode;
386	}