2  * gtf.c  Generate mode timings using the GTF Timing Standard
4  * gcc gtf.c -o gtf -lm -Wall
37  * Standard Version: 1.0, Revision: 1.0
41  * Copyright (c) 1994, 1995, 1996 - Video Electronics Standards
47  * of this standard, the Video Electronics Standards Association and
51  * this standard may be used without restriction.
56  * implementation of the GTF Timing Standard, is available at:
64 #include <xorg-config.h>
84 #define C_PRIME           (((C - J) * K/256.0) + J)
88  * xf86GTFMode() - as defined by the GTF Timing Standard, compute the
91  * output the GTF mode timings.
97  * XServer of fbset mode descriptions, from what I can tell).
103     DisplayModeRec *mode = xnfcalloc(1, sizeof(DisplayModeRec));  in xf86GTFMode()  local
190      *  [H PERIOD EST] = ((1/[V FIELD RATE RQD]) - [MIN VSYNC+BP]/1000000) /  in xf86GTFMode()
195     h_period_est = (((1.0 / v_field_rate_rqd) - (MIN_VSYNC_PLUS_BP / 1000000.0))  in xf86GTFMode()
208      *  [V BACK PORCH] = [V SYNC+BP] - [V SYNC RND]  in xf86GTFMode()
213     v_back_porch = vsync_plus_bp - V_SYNC_RQD;  in xf86GTFMode()
291      *  [IDEAL DUTY CYCLE] = [C'] - ([M']*[H PERIOD]/1000)  in xf86GTFMode()
294     ideal_duty_cycle = C_PRIME - (M_PRIME * h_period / 1000.0);  in xf86GTFMode()
301      *                               (100-[IDEAL DUTY CYCLE]) /  in xf86GTFMode()
308                    (100.0 - ideal_duty_cycle) /  in xf86GTFMode()
348      *  [H FRONT PORCH (PIXELS)] = ([H BLANK (PIXELS)]/2)-[H SYNC (PIXELS)]  in xf86GTFMode()
351     h_front_porch = (h_blank / 2.0) - h_sync;  in xf86GTFMode()
360     /* finally, pack the results in the mode struct */  in xf86GTFMode()
362     mode->HDisplay = (int) (h_pixels_rnd);  in xf86GTFMode()
363     mode->HSyncStart = (int) (h_pixels_rnd + h_front_porch);  in xf86GTFMode()
364     mode->HSyncEnd = (int) (h_pixels_rnd + h_front_porch + h_sync);  in xf86GTFMode()
365     mode->HTotal = (int) (total_pixels);  in xf86GTFMode()
366     mode->VDisplay = (int) (v_lines_rnd);  in xf86GTFMode()
367     mode->VSyncStart = (int) (v_lines_rnd + v_odd_front_porch_lines);  in xf86GTFMode()
368     mode->VSyncEnd = (int) (v_lines_rnd + v_odd_front_porch_lines + V_SYNC_RQD);  in xf86GTFMode()
369     mode->VTotal = (int) (total_v_lines);  in xf86GTFMode()
371     mode->Clock = (int) (pixel_freq * 1000.0);  in xf86GTFMode()
372     mode->HSync = h_freq;  in xf86GTFMode()
373     mode->VRefresh = freq;  in xf86GTFMode()
375     xf86SetModeDefaultName(mode);  in xf86GTFMode()
377     mode->Flags = V_NHSYNC | V_PVSYNC;  in xf86GTFMode()
379         mode->VTotal *= 2;  in xf86GTFMode()
380         mode->Flags |= V_INTERLACE;  in xf86GTFMode()
383     return mode;  in xf86GTFMode()