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RedBear-OS/local/recipes/libs/libxcvt/source/lib/libxcvt.c
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vasilito d551d5dc41 feat: add display stack dependency recipes 
Add lcms2, libdisplay-info, libepoxy, and libxcvt recipes required
by the KWin/Mesa display stack.
2026-05-11 10:10:11 +01:00

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/*
* Copyright 2005-2006 Luc Verhaegen.
* Copyright © 2021 Red Hat, Inc.
*
* 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.
*
*/
/* Standalone VESA CVT standard timing modelines generator. */
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <libxcvt/libxcvt.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
*
*/
struct libxcvt_mode_info *
libxcvt_gen_mode_info(int hdisplay, int vdisplay, float vrefresh, bool reduced, bool interlaced)
{
bool margins = false;
float vfield_rate, hperiod;
int hdisplay_rnd, hmargin;
int vdisplay_rnd, vmargin, vsync;
float interlace; /* Please rename this */
struct libxcvt_mode_info *mode_info;
mode_info = calloc(1, sizeof *mode_info);
if (!mode_info)
return NULL;
mode_info->hdisplay = hdisplay;
mode_info->vdisplay = vdisplay;
mode_info->vrefresh = vrefresh;
/* 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 front porch (lines) - default 3 */
#define CVT_MIN_V_PORCH_RND 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
/* CVT default is 60.0Hz */
if (!mode_info->vrefresh)
mode_info->vrefresh = 60.0;
/* 1. Required field rate */
if (interlaced)
vfield_rate = mode_info->vrefresh * 2;
else
vfield_rate = mode_info->vrefresh;
/* 2. Horizontal pixels */
hdisplay_rnd = mode_info->hdisplay - (mode_info->hdisplay % CVT_H_GRANULARITY);
/* 3. Determine left and right borders */
if (margins) {
/* right margin is actually exactly the same as left */
hmargin = (((float) hdisplay_rnd) * CVT_MARGIN_PERCENTAGE / 100.0);
hmargin -= hmargin % CVT_H_GRANULARITY;
}
else {
hmargin = 0;
}
/* 4. Find total active pixels */
mode_info->hdisplay = hdisplay_rnd + 2 * hmargin;
/* 5. Find number of lines per field */
if (interlaced)
vdisplay_rnd = mode_info->vdisplay / 2;
else
vdisplay_rnd = mode_info->vdisplay;
/* 6. Find top and bottom margins */
/* nope. */
if (margins)
/* top and bottom margins are equal again. */
vmargin = (((float) vdisplay_rnd) * CVT_MARGIN_PERCENTAGE / 100.0);
else
vmargin = 0;
mode_info->vdisplay = mode_info->vdisplay + 2 * vmargin;
/* 7. interlace */
if (interlaced)
interlace = 0.5;
else
interlace = 0.0;
/* Determine vsync Width from aspect ratio */
if (!(mode_info->vdisplay % 3) && ((mode_info->vdisplay * 4 / 3) == mode_info->hdisplay))
vsync = 4;
else if (!(mode_info->vdisplay % 9) && ((mode_info->vdisplay * 16 / 9) == mode_info->hdisplay))
vsync = 5;
else if (!(mode_info->vdisplay % 10) && ((mode_info->vdisplay * 16 / 10) == mode_info->hdisplay))
vsync = 6;
else if (!(mode_info->vdisplay % 4) && ((mode_info->vdisplay * 5 / 4) == mode_info->hdisplay))
vsync = 7;
else if (!(mode_info->vdisplay % 9) && ((mode_info->vdisplay * 15 / 9) == mode_info->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 hblank_percentage;
int vsync_and_back_porch, vback_porch;
int hblank, hsync_w;
/* 8. Estimated Horizontal period */
hperiod = ((float) (1000000.0 / vfield_rate - CVT_MIN_VSYNC_BP)) /
(vdisplay_rnd + 2 * vmargin + CVT_MIN_V_PORCH_RND + interlace);
/* 9. Find number of lines in sync + backporch */
if (((int) (CVT_MIN_VSYNC_BP / hperiod) + 1) <
(vsync + CVT_MIN_V_BPORCH))
vsync_and_back_porch = vsync + CVT_MIN_V_BPORCH;
else
vsync_and_back_porch = (int) (CVT_MIN_VSYNC_BP / hperiod) + 1;
/* 10. Find number of lines in back porch */
vback_porch = vsync_and_back_porch - vsync;
(void) vback_porch;
/* 11. Find total number of lines in vertical field */
mode_info->vtotal =
vdisplay_rnd + 2 * vmargin + vsync_and_back_porch + interlace +
CVT_MIN_V_PORCH_RND;
/* 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 */
hblank_percentage = CVT_C_PRIME - CVT_M_PRIME * hperiod / 1000.0;
/* 13. Blanking time */
if (hblank_percentage < 20)
hblank_percentage = 20;
hblank = mode_info->hdisplay * hblank_percentage / (100.0 - hblank_percentage);
hblank -= hblank % (2 * CVT_H_GRANULARITY);
/* 14. Find total number of pixels in a line. */
mode_info->htotal = mode_info->hdisplay + hblank;
/* Fill in HSync values */
mode_info->hsync_end = mode_info->hdisplay + hblank / 2;
hsync_w = (mode_info->htotal * CVT_HSYNC_PERCENTAGE) / 100;
hsync_w -= hsync_w % CVT_H_GRANULARITY;
mode_info->hsync_start = mode_info->hsync_end - hsync_w;
/* Fill in vsync values */
mode_info->vsync_start = mode_info->vdisplay + CVT_MIN_V_PORCH_RND;
mode_info->vsync_end = mode_info->vsync_start + 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 vblank_interval_lines;
/* 8. Estimate Horizontal period. */
hperiod = ((float) (1000000.0 / vfield_rate - CVT_RB_MIN_VBLANK)) /
(vdisplay_rnd + 2 * vmargin);
/* 9. Find number of lines in vertical blanking */
vblank_interval_lines = ((float) CVT_RB_MIN_VBLANK) / hperiod + 1;
/* 10. Check if vertical blanking is sufficient */
if (vblank_interval_lines < (CVT_RB_VFPORCH + vsync + CVT_MIN_V_BPORCH))
vblank_interval_lines = CVT_RB_VFPORCH + vsync + CVT_MIN_V_BPORCH;
/* 11. Find total number of lines in vertical field */
mode_info->vtotal = vdisplay_rnd + 2 * vmargin + interlace + vblank_interval_lines;
/* 12. Find total number of pixels in a line */
mode_info->htotal = mode_info->hdisplay + CVT_RB_H_BLANK;
/* Fill in HSync values */
mode_info->hsync_end = mode_info->hdisplay + CVT_RB_H_BLANK / 2;
mode_info->hsync_start = mode_info->hsync_end - CVT_RB_H_SYNC;
/* Fill in vsync values */
mode_info->vsync_start = mode_info->vdisplay + CVT_RB_VFPORCH;
mode_info->vsync_end = mode_info->vsync_start + vsync;
}
/* 15/13. Find pixel clock frequency (kHz for xf86) */
mode_info->dot_clock = mode_info->htotal * 1000.0 / hperiod;
mode_info->dot_clock -= mode_info->dot_clock % CVT_CLOCK_STEP;
/* 16/14. Find actual Horizontal Frequency (kHz) */
mode_info->hsync = ((float) mode_info->dot_clock) / ((float) mode_info->htotal);
/* 17/15. Find actual Field rate */
mode_info->vrefresh = (1000.0 * ((float) mode_info->dot_clock)) /
((float) (mode_info->htotal * mode_info->vtotal));
/* 18/16. Find actual vertical frame frequency */
/* ignore - just set the mode flag for interlaced */
if (interlaced)
mode_info->vtotal *= 2;
if (reduced)
mode_info->mode_flags |= LIBXCVT_MODE_FLAG_HSYNC_POSITIVE | LIBXCVT_MODE_FLAG_VSYNC_NEGATIVE;
else
mode_info->mode_flags |= LIBXCVT_MODE_FLAG_HSYNC_NEGATIVE | LIBXCVT_MODE_FLAG_VSYNC_POSITIVE;
if (interlaced)
mode_info->mode_flags |= LIBXCVT_MODE_FLAG_INTERLACE;
/* FWXGA hack adapted from hw/xfree86/modes/xf86EdidModes.c, because you can't say 1366 */
if (mode_info->hdisplay == 1360 && mode_info->vdisplay == 768) {
mode_info->hdisplay = 1366;
mode_info->hsync_start--;
mode_info->hsync_end--;
}
return mode_info;
}
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