/* * 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; }