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+#define DEBUG_VERB 2
+/*
+ * Copyright © 2002 David Dawes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
+ * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * Except as contained in this notice, the name of the author(s) shall
+ * not be used in advertising or otherwise to promote the sale, use or other
+ * dealings in this Software without prior written authorization from
+ * the author(s).
+ *
+ * Authors: David Dawes <dawes@xfree86.org>
+ *
+ * $XFree86: xc/programs/Xserver/hw/xfree86/os-support/vbe/vbeModes.c,v 1.6 2002/11/02 01:38:25 dawes Exp $
+ */
+/*
+ * Modified by Alan Hourihane <alanh@tungstengraphics.com>
+ * to support extended BIOS modes for the Intel chipsets
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+#include <string.h>
+
+#include "xf86.h"
+#include "vbe.h"
+#include "vbeModes.h"
+#include "i830.h"
+#include "i830_modes.h"
+
+#include <math.h>
+
+#define rint(x) floor(x)
+
+#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)
+
+extern const int i830refreshes[];
+
+DisplayModePtr
+i830GetGTF(int h_pixels, int v_lines, float freq, int interlaced, int margins)
+{
+ 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;
+ char modename[20];
+ DisplayModePtr m;
+
+ m = xnfcalloc(sizeof(DisplayModeRec), 1);
+
+
+ /* 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 DisplayMode struct */
+
+ m->HDisplay = (int) (h_pixels_rnd);
+ m->HSyncStart = (int) (h_pixels_rnd + h_front_porch);
+ m->HSyncEnd = (int) (h_pixels_rnd + h_front_porch + h_sync);
+ m->HTotal = (int) (total_pixels);
+
+ m->VDisplay = (int) (v_lines_rnd);
+ m->VSyncStart = (int) (v_lines_rnd + v_odd_front_porch_lines);
+ m->VSyncEnd = (int) (int) (v_lines_rnd + v_odd_front_porch_lines + V_SYNC_RQD);
+ m->VTotal = (int) (total_v_lines);
+
+ m->Clock = (int)(pixel_freq * 1000);
+ m->SynthClock = m->Clock;
+ m->HSync = h_freq;
+ m->VRefresh = v_frame_rate /* freq */;
+
+ snprintf(modename, sizeof(modename), "%dx%d", m->HDisplay,m->VDisplay);
+ m->name = xnfstrdup(modename);
+
+ return (m);
+}
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