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/*
* Copyright 2005-2006 Luc Verhaegen.
*
* 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 COPYRIGHT HOLDER(S) OR 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.
*/
/*
* The reason for having this function in a file of its own is
* so that ../utils/cvt/cvt can link to it, and that xf86CVTMode
* code is shared directly.
*/
#include "xf86.h"
/*
* Generate a CVT standard mode from HDisplay, VDisplay and VRefresh.
*
* These calculations are stolen from the CVT calculation spreadsheet written
* by Graham Loveridge. He seems to be claiming no copyright and there seems to
* be no license attached to this. He apparently just wants to see his name
* mentioned.
*
* This file can be found at http://www.vesa.org/Public/CVT/CVTd6r1.xls
*
* Comments and structure corresponds to the comments and structure of the xls.
* This should ease importing of future changes to the standard (not very
* likely though).
*
* About margins; i'm sure that they are to be the bit between HDisplay and
* HBlankStart, HBlankEnd and HTotal, VDisplay and VBlankStart, VBlankEnd and
* VTotal, where the overscan colour is shown. FB seems to call _all_ blanking
* outside sync "margin" for some reason. Since we prefer seeing proper
* blanking instead of the overscan colour, and since the Crtc* values will
* probably get altered after us, we will disable margins altogether. With
* these calculations, Margins will plainly expand H/VDisplay, and we don't
* want that. -- libv
*
*/
_X_EXPORT DisplayModePtr
xf86CVTMode(int HDisplay, int VDisplay, float VRefresh, Bool Reduced,
Bool Interlaced)
{
DisplayModeRec *Mode = xnfcalloc(1, sizeof(DisplayModeRec));
/* 1) top/bottom margin size (% of height) - default: 1.8 */
#define CVT_MARGIN_PERCENTAGE 1.8
/* 2) character cell horizontal granularity (pixels) - default 8 */
#define CVT_H_GRANULARITY 8
/* 4) Minimum vertical porch (lines) - default 3 */
#define CVT_MIN_V_PORCH 3
/* 4) Minimum number of vertical back porch lines - default 6 */
#define CVT_MIN_V_BPORCH 6
/* Pixel Clock step (kHz) */
#define CVT_CLOCK_STEP 250
Bool Margins = FALSE;
float VFieldRate, HPeriod;
int HDisplayRnd, HMargin;
int VDisplayRnd, VMargin, VSync;
float Interlace; /* Please rename this */
/* CVT default is 60.0Hz */
if (!VRefresh)
VRefresh = 60.0;
/* 1. Required field rate */
if (Interlaced)
VFieldRate = VRefresh * 2;
else
VFieldRate = VRefresh;
/* 2. Horizontal pixels */
HDisplayRnd = HDisplay - (HDisplay % CVT_H_GRANULARITY);
/* 3. Determine left and right borders */
if (Margins) {
/* right margin is actually exactly the same as left */
HMargin = (((float) HDisplayRnd) * CVT_MARGIN_PERCENTAGE / 100.0);
HMargin -= HMargin % CVT_H_GRANULARITY;
} else
HMargin = 0;
/* 4. Find total active pixels */
Mode->HDisplay = HDisplayRnd + 2*HMargin;
/* 5. Find number of lines per field */
if (Interlaced)
VDisplayRnd = VDisplay / 2;
else
VDisplayRnd = VDisplay;
/* 6. Find top and bottom margins */
/* nope. */
if (Margins)
/* top and bottom margins are equal again. */
VMargin = (((float) VDisplayRnd) * CVT_MARGIN_PERCENTAGE / 100.0);
else
VMargin = 0;
Mode->VDisplay = VDisplay + 2*VMargin;
/* 7. Interlace */
if (Interlaced)
Interlace = 0.5;
else
Interlace = 0.0;
/* Determine VSync Width from aspect ratio */
if (!(VDisplay % 3) && ((VDisplay * 4 / 3) == HDisplay))
VSync = 4;
else if (!(VDisplay % 9) && ((VDisplay * 16 / 9) == HDisplay))
VSync = 5;
else if (!(VDisplay % 10) && ((VDisplay * 16 / 10) == HDisplay))
VSync = 6;
else if (!(VDisplay % 4) && ((VDisplay * 5 / 4) == HDisplay))
VSync = 7;
else if (!(VDisplay % 9) && ((VDisplay * 15 / 9) == HDisplay))
VSync = 7;
else /* Custom */
VSync = 10;
if (!Reduced) { /* simplified GTF calculation */
/* 4) Minimum time of vertical sync + back porch interval (µs)
* default 550.0 */
#define CVT_MIN_VSYNC_BP 550.0
/* 3) Nominal HSync width (% of line period) - default 8 */
#define CVT_HSYNC_PERCENTAGE 8
float HBlankPercentage;
int VSyncAndBackPorch, VBackPorch;
int HBlank;
/* 8. Estimated Horizontal period */
HPeriod = ((float) (1000000.0 / VFieldRate - CVT_MIN_VSYNC_BP)) /
(VDisplayRnd + 2 * VMargin + CVT_MIN_V_PORCH + Interlace);
/* 9. Find number of lines in sync + backporch */
if (((int)(CVT_MIN_VSYNC_BP / HPeriod) + 1) < (VSync + CVT_MIN_V_PORCH))
VSyncAndBackPorch = VSync + CVT_MIN_V_PORCH;
else
VSyncAndBackPorch = (int)(CVT_MIN_VSYNC_BP / HPeriod) + 1;
/* 10. Find number of lines in back porch */
VBackPorch = VSyncAndBackPorch - VSync;
/* 11. Find total number of lines in vertical field */
Mode->VTotal = VDisplayRnd + 2 * VMargin + VSyncAndBackPorch + Interlace
+ CVT_MIN_V_PORCH;
/* 5) Definition of Horizontal blanking time limitation */
/* Gradient (%/kHz) - default 600 */
#define CVT_M_FACTOR 600
/* Offset (%) - default 40 */
#define CVT_C_FACTOR 40
/* Blanking time scaling factor - default 128 */
#define CVT_K_FACTOR 128
/* Scaling factor weighting - default 20 */
#define CVT_J_FACTOR 20
#define CVT_M_PRIME CVT_M_FACTOR * CVT_K_FACTOR / 256
#define CVT_C_PRIME (CVT_C_FACTOR - CVT_J_FACTOR) * CVT_K_FACTOR / 256 + \
CVT_J_FACTOR
/* 12. Find ideal blanking duty cycle from formula */
HBlankPercentage = CVT_C_PRIME - CVT_M_PRIME * HPeriod/1000.0;
/* 13. Blanking time */
if (HBlankPercentage < 20)
HBlankPercentage = 20;
HBlank = Mode->HDisplay * HBlankPercentage/(100.0 - HBlankPercentage);
HBlank -= HBlank % (2*CVT_H_GRANULARITY);
/* 14. Find total number of pixels in a line. */
Mode->HTotal = Mode->HDisplay + HBlank;
/* Fill in HSync values */
Mode->HSyncEnd = Mode->HDisplay + HBlank / 2;
Mode->HSyncStart = Mode->HSyncEnd -
(Mode->HTotal * CVT_HSYNC_PERCENTAGE) / 100;
Mode->HSyncStart += CVT_H_GRANULARITY -
Mode->HSyncStart % CVT_H_GRANULARITY;
/* Fill in VSync values */
Mode->VSyncStart = Mode->VDisplay + CVT_MIN_V_PORCH;
Mode->VSyncEnd = Mode->VSyncStart + VSync;
} else { /* Reduced blanking */
/* Minimum vertical blanking interval time (µs) - default 460 */
#define CVT_RB_MIN_VBLANK 460.0
/* Fixed number of clocks for horizontal sync */
#define CVT_RB_H_SYNC 32.0
/* Fixed number of clocks for horizontal blanking */
#define CVT_RB_H_BLANK 160.0
/* Fixed number of lines for vertical front porch - default 3 */
#define CVT_RB_VFPORCH 3
int VBILines;
/* 8. Estimate Horizontal period. */
HPeriod = ((float) (1000000.0 / VFieldRate - CVT_RB_MIN_VBLANK)) /
(VDisplayRnd + 2*VMargin);
/* 9. Find number of lines in vertical blanking */
VBILines = ((float) CVT_RB_MIN_VBLANK) / HPeriod + 1;
/* 10. Check if vertical blanking is sufficient */
if (VBILines < (CVT_RB_VFPORCH + VSync + CVT_MIN_V_BPORCH))
VBILines = CVT_RB_VFPORCH + VSync + CVT_MIN_V_BPORCH;
/* 11. Find total number of lines in vertical field */
Mode->VTotal = VDisplayRnd + 2 * VMargin + Interlace + VBILines;
/* 12. Find total number of pixels in a line */
Mode->HTotal = Mode->HDisplay + CVT_RB_H_BLANK;
/* Fill in HSync values */
Mode->HSyncEnd = Mode->HDisplay + CVT_RB_H_BLANK / 2;
Mode->HSyncStart = Mode->HSyncEnd - CVT_RB_H_SYNC;
/* Fill in VSync values */
Mode->VSyncStart = Mode->VDisplay + CVT_RB_VFPORCH;
Mode->VSyncEnd = Mode->VSyncStart + VSync;
}
/* 15/13. Find pixel clock frequency (kHz for xf86) */
Mode->Clock = Mode->HTotal * 1000.0 / HPeriod;
Mode->Clock -= Mode->Clock % CVT_CLOCK_STEP;
/* 16/14. Find actual Horizontal Frequency (kHz) */
Mode->HSync = ((float) Mode->Clock) / ((float) Mode->HTotal);
/* 17/15. Find actual Field rate */
Mode->VRefresh = (1000.0 * ((float) Mode->Clock)) /
((float) (Mode->HTotal * Mode->VTotal));
/* 18/16. Find actual vertical frame frequency */
/* ignore - just set the mode flag for interlaced */
if (Interlaced)
Mode->VTotal *= 2;
{
char Name[256];
Name[0] = 0;
snprintf(Name, 256, "%dx%d", HDisplay, VDisplay);
Mode->name = xnfalloc(strlen(Name) + 1);
memcpy(Mode->name, Name, strlen(Name) + 1);
}
if (Reduced)
Mode->Flags |= V_PHSYNC | V_NVSYNC;
else
Mode->Flags |= V_NHSYNC | V_PVSYNC;
if (Interlaced)
Mode->Flags |= V_INTERLACE;
return Mode;
}
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