SvgaLib/utils/gtf/gtfcalc.c

/****************************************************************************
*
*				 	VESA Generalized Timing Formula (GTF)
*								Version 1.1
*
*  ========================================================================
*
*    The contents of this file are subject to the SciTech MGL Public
*    License Version 1.0 (the "License"); you may not use this file
*    except in compliance with the License. You may obtain a copy of
*    the License at http://www.scitechsoft.com/mgl-license.txt
*
*    Software distributed under the License is distributed on an
*    "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
*    implied. See the License for the specific language governing
*    rights and limitations under the License.
*
*    The Original Code is Copyright (C) 1991-1998 SciTech Software, Inc.
*
*    The Initial Developer of the Original Code is SciTech Software, Inc.
*    All Rights Reserved.
*
*  ========================================================================
*
* Developed by:	SciTech Software, Inc.
*
* Language:     ANSI C
* Environment:  Any.
*
* Description:  C module for generating GTF compatible timings given a set
*				of input requirements. Translated from the original GTF
*				1.14 spreadsheet definition.
*
*				Compile with #define TESTING to build a command line test
*				program.
*
*				NOTE: The code in here has been written for clarity and
*					  to follow the original GTF spec as closely as
*					  possible.
*
****************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <math.h>
#include "gtf.h"

/*------------------------- Global Variables ------------------------------*/

static GTF_constants GC = {
	1.8,					/* Margin size as percentage of display		*/
	8,						/* Character cell granularity				*/
	1,						/* Minimum front porch in lines/chars		*/
	3,						/* Width of V sync in lines					*/
	8,						/* Width of H sync as percent of total		*/
	550,					/* Minimum vertical sync + back porch (us)	*/
	600,					/* Blanking formula gradient				*/
	40,						/* Blanking formula offset					*/
	128,					/* Blanking formula scaling factor			*/
	20,						/* Blanking formula scaling factor weight	*/
	};

/*-------------------------- Implementation -------------------------------*/

static double round(double v)
{
	return floor(v + 0.5);
}

static void GetInternalConstants(GTF_constants *c)
/****************************************************************************
*
* Function:		GetInternalConstants
* Parameters:	c	- Place to store the internal constants
*
* Description:  Calculates the rounded, internal set of GTF constants.
*				These constants are different to the real GTF constants
*				that can be set up for the monitor. The calculations to
*				get these real constants are defined in the 'Work Area'
*				after the constants are defined in the Excel spreadsheet.
*
****************************************************************************/
{
	c->margin = GC.margin;
	c->cellGran = round(GC.cellGran);
	c->minPorch = round(GC.minPorch);
	c->vSyncRqd = round(GC.vSyncRqd);
	c->hSync = GC.hSync;
	c->minVSyncBP = GC.minVSyncBP;
	if (GC.k == 0)
		c->k = 0.001;
	else
		c->k = GC.k;
	c->m = (c->k / 256) * GC.m;
	c->c = (GC.c - GC.j) * (c->k / 256) + GC.j;
	c->j = GC.j;
}

void GTF_calcTimings(double hPixels,double vLines,double freq,
	int type,ibool wantMargins,ibool wantInterlace,GTF_timings *t)
/****************************************************************************
*
* Function:		GTF_calcTimings
* Parameters:	hPixels		- X resolution
*				vLines		- Y resolution
*				freq		- Frequency (Hz, KHz or MHz depending on type)
*				type		- 1 - vertical, 2 - horizontal, 3 - dot clock
*				margins		- True if margins should be generated
*				interlace	- True if interlaced timings to be generated
*				t			- Place to store the resulting timings
*
* Description:  Calculates a set of GTF timing parameters given a specified
*				resolution and vertical frequency. The horizontal frequency
*				and dot clock will be automatically generated by this
*				routines.
*
*				For interlaced modes the CRTC parameters are calculated for
*				a single field, so will be half what would be used in
*				a non-interlaced mode.
*
****************************************************************************/
{
	double  		interlace,vFieldRate,hPeriod;
	double  		topMarginLines,botMarginLines;
	double  		leftMarginPixels,rightMarginPixels;
	double			hPeriodEst,vSyncBP,vBackPorch;
	double			vTotalLines,vFieldRateEst;
	double			hTotalPixels,hTotalActivePixels,hBlankPixels;
	double			idealDutyCycle,hSyncWidth,hSyncBP,hBackPorch;
	double			idealHPeriod;
	double			vFreq,hFreq,dotClock;
	GTF_constants   c;

	/* Get rounded GTF constants used for internal calculations */
	GetInternalConstants(&c);

	/* Move input parameters into appropriate variables */
	vFreq = hFreq = dotClock = freq;

	/* Round pixels to character cell granularity */
	hPixels = round(hPixels / c.cellGran) * c.cellGran;

	/* For interlaced mode halve the vertical parameters, and double
	 * the required field refresh rate.
	 */
	if (wantInterlace) {
		vLines = round(vLines / 2);
		vFieldRate = vFreq * 2;
		dotClock = dotClock * 2;
		interlace = 0.5;
		}
	else {
		vFieldRate = vFreq;
		interlace = 0;
		}

	/* Determine the lines for margins */
	if (wantMargins) {
		topMarginLines = round(c.margin / 100 * vLines);
		botMarginLines = round(c.margin / 100 * vLines);
		}
	else {
		topMarginLines = 0;
		botMarginLines = 0;
		}

	if (type != GTF_lockPF) {
		if (type == GTF_lockVF) {
			/* Estimate the horizontal period */
			hPeriodEst = ((1/vFieldRate) - (c.minVSyncBP/1000000)) /
				(vLines + (2*topMarginLines) + c.minPorch + interlace) * 1000000;

			/* Find the number of lines in vSync + back porch */
			vSyncBP = round(c.minVSyncBP / hPeriodEst);
			}
		else if (type == GTF_lockHF) {
			/* Find the number of lines in vSync + back porch */
			vSyncBP = round((c.minVSyncBP * hFreq) / 1000);
			}

		/* Find the number of lines in the V back porch alone */
		vBackPorch = vSyncBP - c.vSyncRqd;

		/* Find the total number of lines in the vertical period */
		vTotalLines = vLines + topMarginLines + botMarginLines + vSyncBP
			+ interlace + c.minPorch;

		if (type == GTF_lockVF) {
			/* Estimate the vertical frequency */
			vFieldRateEst = 1000000 / (hPeriodEst * vTotalLines);

			/* Find the actual horizontal period */
			hPeriod = (hPeriodEst * vFieldRateEst) / vFieldRate;

			/* Find the actual vertical field frequency */
			vFieldRate = 1000000 / (hPeriod * vTotalLines);
			}
		else if (type == GTF_lockHF) {
			/* Find the actual vertical field frequency */
			vFieldRate = (hFreq / vTotalLines) * 1000;
			}
		}

	/* Find the number of pixels in the left and right margins */
	if (wantMargins) {
		leftMarginPixels = round(hPixels * c.margin) / (100 * c.cellGran);
		rightMarginPixels = round(hPixels * c.margin) / (100 * c.cellGran);
		}
	else {
		leftMarginPixels = 0;
		rightMarginPixels = 0;
		}

	/* Find the total number of active pixels in image + margins */
	hTotalActivePixels = hPixels + leftMarginPixels + rightMarginPixels;

	if (type == GTF_lockVF) {
		/* Find the ideal blanking duty cycle */
		idealDutyCycle = c.c - ((c.m * hPeriod) / 1000);
		}
	else if (type == GTF_lockHF) {
		/* Find the ideal blanking duty cycle */
		idealDutyCycle = c.c - (c.m / hFreq);
		}
	else if (type == GTF_lockPF) {
		/* Find ideal horizontal period from blanking duty cycle formula */
		idealHPeriod = (((c.c - 100) + (sqrt((pow(100-c.c,2)) +
			(0.4 * c.m * (hTotalActivePixels + rightMarginPixels +
			leftMarginPixels) / dotClock)))) / (2 * c.m)) * 1000;

		/* Find the ideal blanking duty cycle */
		idealDutyCycle = c.c - ((c.m * idealHPeriod) / 1000);
		}

	/* Find the number of pixels in blanking time */
	hBlankPixels = round((hTotalActivePixels * idealDutyCycle) /
		((100 - idealDutyCycle) * 2 * c.cellGran)) * (2 * c.cellGran);

	/* Find the total number of pixels */
	hTotalPixels = hTotalActivePixels + hBlankPixels;

	/* Find the horizontal back porch */
	hBackPorch = round((hBlankPixels / 2) / c.cellGran) * c.cellGran;

	/* Find the horizontal sync width */
	hSyncWidth = round(((c.hSync/100) * hTotalPixels) / c.cellGran) * c.cellGran;

	/* Find the horizontal sync + back porch */
	hSyncBP = hBackPorch + hSyncWidth;

	if (type == GTF_lockPF) {
		/* Find the horizontal frequency */
		hFreq = (dotClock / hTotalPixels) * 1000;

		/* Find the horizontal period */
		hPeriod = 1000 / hFreq;

		/* Find the number of lines in vSync + back porch */
		vSyncBP = round((c.minVSyncBP * hFreq) / 1000);

		/* Find the number of lines in the V back porch alone */
		vBackPorch = vSyncBP - c.vSyncRqd;

		/* Find the total number of lines in the vertical period */
		vTotalLines = vLines + topMarginLines + botMarginLines + vSyncBP
			+ interlace + c.minPorch;

		/* Find the actual vertical field frequency */
		vFieldRate = (hFreq / vTotalLines) * 1000;
		}
	else {
		if (type == GTF_lockVF) {
			/* Find the horizontal frequency */
			hFreq = 1000 / hPeriod;
			}
		else if (type == GTF_lockHF) {
			/* Find the horizontal frequency */
			hPeriod = 1000 / hFreq;
			}

		/* Find the pixel clock frequency */
		dotClock = hTotalPixels / hPeriod;
		}

	/* Find the vertical frame frequency */
	if (wantInterlace) {
		vFreq = vFieldRate / 2;
		dotClock = dotClock / 2;
		}
	else
		vFreq = vFieldRate;

	/* Return the computed frequencies */
	t->vFreq = vFreq;
	t->hFreq = hFreq;
	t->dotClock = dotClock;

	/* Determine the vertical timing parameters */
	t->h.hTotal = hTotalPixels;
	t->h.hDisp = hTotalActivePixels;
	t->h.hSyncStart = t->h.hTotal - hSyncBP;
	t->h.hSyncEnd = t->h.hTotal - hBackPorch;
	t->h.hFrontPorch = t->h.hSyncStart - t->h.hDisp;
	t->h.hSyncWidth = hSyncWidth;
	t->h.hBackPorch = hBackPorch;

	/* Determine the vertical timing parameters */
	t->v.vTotal = vTotalLines;
	t->v.vDisp = vLines;
	t->v.vSyncStart = t->v.vTotal - vSyncBP;
	t->v.vSyncEnd = t->v.vTotal - vBackPorch;
	t->v.vFrontPorch = t->v.vSyncStart - t->v.vDisp;
	t->v.vSyncWidth = c.vSyncRqd;
	t->v.vBackPorch = vBackPorch;

	/* Mark as GTF timing using the sync polarities */
	t->interlace = (wantInterlace) ? 'I' : 'N';
	t->hSyncPol = '-';
	t->vSyncPol = '+';
}

void GTF_getConstants(GTF_constants *constants)
{ *constants = GC; }

void GTF_setConstants(GTF_constants *constants)
{ GC = *constants; }

#ifdef	TESTING_GTF

int main(int argc,char *argv[])
{
	FILE		*f;
	double		xPixels,yPixels,freq;
	ibool		interlace;
	GTF_timings	t;

	if (argc != 5 && argc != 6) {
		printf("Usage: GTFCALC <xPixels> <yPixels> <freq> [[Hz] [KHz] [MHz]] [I]\n");
		printf("\n");
		printf("where <xPixels> is the horizontal resolution of the mode, <yPixels> is the\n");
		printf("vertical resolution of the mode. The <freq> value will be the frequency to\n");
		printf("drive the calculations, and will be either the vertical frequency (in Hz)\n");
		printf("the horizontal frequency (in KHz) or the dot clock (in MHz). To generate\n");
		printf("timings for an interlaced mode, add 'I' to the end of the command line.\n");
		printf("\n");
		printf("For example to generate timings for 640x480 at 60Hz vertical:\n");
		printf("\n");
		printf("    GTFCALC 640 480 60 Hz\n");
		printf("\n");
		printf("For example to generate timings for 640x480 at 31.5KHz horizontal:\n");
		printf("\n");
		printf("    GTFCALC 640 480 31.5 KHz\n");
		printf("\n");
		printf("For example to generate timings for 640x480 with a 25.175Mhz dot clock:\n");
		printf("\n");
		printf("    GTFCALC 640 480 25.175 MHz\n");
		printf("\n");
		printf("GTFCALC will print a summary of the results found, and dump the CRTC\n");
		printf("values to the UVCONFIG.CRT file in the format used by SciTech Display Doctor.\n");
		return 1;
		}

	/* Get values from command line */
	xPixels = atof(argv[1]);
	yPixels = atof(argv[2]);
	freq = atof(argv[3]);
	interlace = ((argc == 6) && (argv[5][0] == 'I'));

	/* Compute the CRTC timings */
	if (toupper(argv[4][0]) == 'H')
		GTF_calcTimings(xPixels,yPixels,freq,GTF_lockVF,false,interlace,&t);
	else if (toupper(argv[4][0]) == 'K')
		GTF_calcTimings(xPixels,yPixels,freq,GTF_lockHF,false,interlace,&t);
	else if (toupper(argv[4][0]) == 'M')
		GTF_calcTimings(xPixels,yPixels,freq,GTF_lockPF,false,interlace,&t);
	else {
		printf("Unknown command line!\n");
		return 1;
		}

	/* Dump summary info to standard output */
	printf("CRTC values for %.0fx%.0f @ %.2f %s\n", xPixels, yPixels, freq, argv[4]);
	printf("\n");
	printf("  hTotal      = %-4d    vTotal      = %-4d\n",
		t.h.hTotal, t.v.vTotal);
	printf("  hDisp       = %-4d    vDisp       = %-4d\n",
		t.h.hDisp, t.v.vDisp);
	printf("  hSyncStart  = %-4d    vSyncStart  = %-4d\n",
		t.h.hSyncStart, t.v.vSyncStart);
	printf("  hSyncEnd    = %-4d    vSyncEnd    = %-4d\n",
		t.h.hSyncEnd, t.v.vSyncEnd);
	printf("  hFrontPorch = %-4d    vFrontPorch = %-4d\n",
		t.h.hFrontPorch, t.v.vFrontPorch);
	printf("  hSyncWidth  = %-4d    vSyncWidth  = %-4d\n",
		t.h.hSyncWidth, t.v.vSyncWidth);
	printf("  hBackPorch  = %-4d    vBackPorch  = %-4d\n",
		t.h.hBackPorch, t.v.vBackPorch);
	printf("\n");
	printf("  Interlaced  = %s\n", (t.interlace == 'I') ? "Yes" : "No");
	printf("  H sync pol  = %c\n", t.hSyncPol);
	printf("  V sync pol  = %c\n", t.vSyncPol);
	printf("\n");
	printf("  Vert freq   = %.2f Hz\n", t.vFreq);
	printf("  Horiz freq  = %.2f KHz\n", t.hFreq);
	printf("  Dot Clock   = %.2f Mhz\n",	t.dotClock);
        fprintf(stderr,"Modeline %c%ix%i@%.0f%c %.3f %i %i %i %i %i %i %i %i %s %chsync %cvsync\n",
           		     '"',t.h.hDisp,t.v.vDisp,t.vFreq,'"',
                 	     t.dotClock, 
           		     t.h.hDisp,		
           		     t.h.hSyncStart,
           		     t.h.hSyncEnd,
                             t.h.hTotal,
                             t.v.vDisp,
                             t.v.vSyncStart,
                             t.v.vSyncEnd,
                             t.v.vTotal,
                             (t.interlace == 'I') ? "Interlace" : "",
                             t.hSyncPol,
                             t.vSyncPol                             
                             );

	/* Dump to file in format used by SciTech Display Doctor */
	if ((f = fopen("UVCONFIG.CRT","wt")) != NULL) {
		fprintf(f, "[%.0f %.0f]\n", xPixels, yPixels);
		fprintf(f, "%d %d %d %d '%c' %s\n",
			t.h.hTotal, t.h.hDisp,
			t.h.hSyncStart, t.h.hSyncEnd,
			t.hSyncPol, (t.interlace == 'I') ? "I" : "NI");
		fprintf(f, "%d %d %d %d '%c'\n",
			t.v.vTotal, t.v.vDisp,
			t.v.vSyncStart, t.v.vSyncEnd,
			t.vSyncPol);
		fprintf(f, "%.2f\n", t.dotClock);
		fclose(f);
		}
	return 0;
}

#endif	/* TESTING */