xref: /freebsd/sys/dev/videomode/pickmode.c (revision edf8578117e8844e02c0121147f45e4609b30680)
1 /* $NetBSD: pickmode.c,v 1.3 2011/04/09 18:22:31 jdc Exp $ */
2 
3 /*-
4  * Copyright (c) 2006 The NetBSD Foundation
5  * All rights reserved.
6  *
7  * this code was contributed to The NetBSD Foundation by Michael Lorenz
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  *
18  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS
19  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
20  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE NETBSD FOUNDATION BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
24  * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
26  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
27  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
28  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29  */
30 
31 #include <sys/cdefs.h>
32 #include <sys/param.h>
33 #include <sys/libkern.h>
34 #include <dev/videomode/videomode.h>
35 #include "opt_videomode.h"
36 
37 #ifdef PICKMODE_DEBUG
38 #define DPRINTF printf
39 #else
40 #define DPRINTF while (0) printf
41 #endif
42 
43 const struct videomode *
44 pick_mode_by_dotclock(int width, int height, int dotclock)
45 {
46 	const struct videomode *this, *best = NULL;
47 	int i;
48 
49 	DPRINTF("%s: looking for %d x %d at up to %d kHz\n", __func__, width,
50 	    height, dotclock);
51 	for (i = 0; i < videomode_count; i++) {
52 		this = &videomode_list[i];
53 		if ((this->hdisplay != width) || (this->vdisplay != height) ||
54 		    (this->dot_clock > dotclock))
55 			continue;
56 		if (best != NULL) {
57 			if (this->dot_clock > best->dot_clock)
58 				best = this;
59 		} else
60 			best = this;
61 	}
62 	if (best != NULL)
63 		DPRINTF("found %s\n", best->name);
64 
65 	return best;
66 }
67 
68 const struct videomode *
69 pick_mode_by_ref(int width, int height, int refresh)
70 {
71 	const struct videomode *this, *best = NULL;
72 	int mref, closest = 1000, i, diff;
73 
74 	DPRINTF("%s: looking for %d x %d at up to %d Hz\n", __func__, width,
75 	    height, refresh);
76 	for (i = 0; i < videomode_count; i++) {
77 		this = &videomode_list[i];
78 		mref = this->dot_clock * 1000 / (this->htotal * this->vtotal);
79 		diff = abs(mref - refresh);
80 		if ((this->hdisplay != width) || (this->vdisplay != height))
81 			continue;
82 		DPRINTF("%s in %d hz, diff %d\n", this->name, mref, diff);
83 		if (best != NULL) {
84 			if (diff < closest) {
85 				best = this;
86 				closest = diff;
87 			}
88 		} else {
89 			best = this;
90 			closest = diff;
91 		}
92 	}
93 	if (best != NULL)
94 		DPRINTF("found %s %d\n", best->name, best->dot_clock);
95 
96 	return best;
97 }
98 
99 static inline void
100 swap_modes(struct videomode *left, struct videomode *right)
101 {
102 	struct videomode temp;
103 
104 	temp = *left;
105 	*left = *right;
106 	*right = temp;
107 }
108 
109 /*
110  * Sort modes by refresh rate, aspect ratio (*), then resolution.
111  * Preferred mode or largest mode is first in the list and other modes
112  * are sorted on closest match to that mode.
113  * (*) Note that the aspect ratio calculation treats "close" aspect ratios
114  * (within 12.5%) as the same for this purpose.
115  */
116 #define	DIVIDE(x, y)	(((x) + ((y) / 2)) / (y))
117 void
118 sort_modes(struct videomode *modes, struct videomode **preferred, int nmodes)
119 {
120 	int aspect, refresh, hbest, vbest, abest, atemp, rbest, rtemp;
121 	int i, j;
122 	struct videomode *mtemp = NULL;
123 
124 	if (nmodes < 2)
125 		return;
126 
127 	if (*preferred != NULL) {
128 		/* Put the preferred mode first in the list */
129 		aspect = (*preferred)->hdisplay * 100 / (*preferred)->vdisplay;
130 		refresh = DIVIDE(DIVIDE((*preferred)->dot_clock * 1000,
131 		    (*preferred)->htotal), (*preferred)->vtotal);
132 		if (*preferred != modes) {
133 			swap_modes(*preferred, modes);
134 			*preferred = modes;
135 		}
136 	} else {
137 		/*
138 		 * Find the largest horizontal and vertical mode and put that
139 		 * first in the list.  Preferred refresh rate is taken from
140 		 * the first mode of this size.
141 		 */
142 		hbest = 0;
143 		vbest = 0;
144 		for (i = 0; i < nmodes; i++) {
145 			if (modes[i].hdisplay > hbest) {
146 				hbest = modes[i].hdisplay;
147 				vbest = modes[i].vdisplay;
148 				mtemp = &modes[i];
149 			} else if (modes[i].hdisplay == hbest &&
150 			    modes[i].vdisplay > vbest) {
151 				vbest = modes[i].vdisplay;
152 				mtemp = &modes[i];
153 			}
154 		}
155 		aspect = mtemp->hdisplay * 100 / mtemp->vdisplay;
156 		refresh = DIVIDE(DIVIDE(mtemp->dot_clock * 1000,
157 		    mtemp->htotal), mtemp->vtotal);
158 		if (mtemp != modes)
159 			swap_modes(mtemp, modes);
160 	}
161 
162 	/* Sort other modes by refresh rate, aspect ratio, then resolution */
163 	for (j = 1; j < nmodes - 1; j++) {
164 		rbest = 1000;
165 		abest = 1000;
166 		hbest = 0;
167 		vbest = 0;
168 		for (i = j; i < nmodes; i++) {
169 			rtemp = abs(refresh -
170 			    DIVIDE(DIVIDE(modes[i].dot_clock * 1000,
171 			    modes[i].htotal), modes[i].vtotal));
172 			atemp = (modes[i].hdisplay * 100 / modes[i].vdisplay);
173 			if (rtemp < rbest) {
174 				rbest = rtemp;
175 				mtemp = &modes[i];
176 			}
177 			if (rtemp == rbest) {
178 				/* Treat "close" aspect ratios as identical */
179 				if (abs(abest - atemp) > (abest / 8) &&
180 				    abs(aspect - atemp) < abs(aspect - abest)) {
181 					abest = atemp;
182 					mtemp = &modes[i];
183 				}
184 				if (atemp == abest ||
185 				    abs(abest - atemp) <= (abest / 8)) {
186 					if (modes[i].hdisplay > hbest) {
187 						hbest = modes[i].hdisplay;
188 						mtemp = &modes[i];
189 					}
190 					if (modes[i].hdisplay == hbest &&
191 					    modes[i].vdisplay > vbest) {
192 						vbest = modes[i].vdisplay;
193 						mtemp = &modes[i];
194 					}
195 				}
196 			}
197 		}
198 		if (mtemp != &modes[j])
199 			swap_modes(mtemp, &modes[j]);
200 	}
201 }
202