1/* $NetBSD: pickmode.c,v 1.3 2011/04/09 18:22:31 jdc Exp $ */
2/* $FreeBSD$ */
3
4/*-
5 * Copyright (c) 2006 The NetBSD Foundation
6 * All rights reserved.
7 *
8 * this code was contributed to The NetBSD Foundation by Michael Lorenz
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS
20 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
21 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE NETBSD FOUNDATION BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
25 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
27 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33__FBSDID("$FreeBSD$");
34
35#include <sys/param.h>
36#include <sys/libkern.h>
37#include <dev/videomode/videomode.h>
38#include "opt_videomode.h"
39
40#ifdef PICKMODE_DEBUG
41#define DPRINTF printf
42#else
43#define DPRINTF while (0) printf
44#endif
45
46const struct videomode *
47pick_mode_by_dotclock(int width, int height, int dotclock)
48{
49	const struct videomode *this, *best = NULL;
50	int i;
51
52	DPRINTF("%s: looking for %d x %d at up to %d kHz\n", __func__, width,
53	    height, dotclock);
54	for (i = 0; i < videomode_count; i++) {
55		this = &videomode_list[i];
56		if ((this->hdisplay != width) || (this->vdisplay != height) ||
57		    (this->dot_clock > dotclock))
58			continue;
59		if (best != NULL) {
60			if (this->dot_clock > best->dot_clock)
61				best = this;
62		} else
63			best = this;
64	}
65	if (best != NULL)
66		DPRINTF("found %s\n", best->name);
67
68	return best;
69}
70
71const struct videomode *
72pick_mode_by_ref(int width, int height, int refresh)
73{
74	const struct videomode *this, *best = NULL;
75	int mref, closest = 1000, i, diff;
76
77	DPRINTF("%s: looking for %d x %d at up to %d Hz\n", __func__, width,
78	    height, refresh);
79	for (i = 0; i < videomode_count; i++) {
80
81		this = &videomode_list[i];
82		mref = this->dot_clock * 1000 / (this->htotal * this->vtotal);
83		diff = abs(mref - refresh);
84		if ((this->hdisplay != width) || (this->vdisplay != height))
85			continue;
86		DPRINTF("%s in %d hz, diff %d\n", this->name, mref, diff);
87		if (best != NULL) {
88			if (diff < closest) {
89				best = this;
90				closest = diff;
91			}
92		} else {
93			best = this;
94			closest = diff;
95		}
96	}
97	if (best != NULL)
98		DPRINTF("found %s %d\n", best->name, best->dot_clock);
99
100	return best;
101}
102
103static inline void
104swap_modes(struct videomode *left, struct videomode *right)
105{
106	struct videomode temp;
107
108	temp = *left;
109	*left = *right;
110	*right = temp;
111}
112
113/*
114 * Sort modes by refresh rate, aspect ratio (*), then resolution.
115 * Preferred mode or largest mode is first in the list and other modes
116 * are sorted on closest match to that mode.
117 * (*) Note that the aspect ratio calculation treats "close" aspect ratios
118 * (within 12.5%) as the same for this purpose.
119 */
120#define	DIVIDE(x, y)	(((x) + ((y) / 2)) / (y))
121void
122sort_modes(struct videomode *modes, struct videomode **preferred, int nmodes)
123{
124	int aspect, refresh, hbest, vbest, abest, atemp, rbest, rtemp;
125	int i, j;
126	struct videomode *mtemp = NULL;
127
128	if (nmodes < 2)
129		return;
130
131	if (*preferred != NULL) {
132		/* Put the preferred mode first in the list */
133		aspect = (*preferred)->hdisplay * 100 / (*preferred)->vdisplay;
134		refresh = DIVIDE(DIVIDE((*preferred)->dot_clock * 1000,
135		    (*preferred)->htotal), (*preferred)->vtotal);
136		if (*preferred != modes) {
137			swap_modes(*preferred, modes);
138			*preferred = modes;
139		}
140	} else {
141		/*
142		 * Find the largest horizontal and vertical mode and put that
143		 * first in the list.  Preferred refresh rate is taken from
144		 * the first mode of this size.
145		 */
146		hbest = 0;
147		vbest = 0;
148		for (i = 0; i < nmodes; i++) {
149			if (modes[i].hdisplay > hbest) {
150				hbest = modes[i].hdisplay;
151				vbest = modes[i].vdisplay;
152				mtemp = &modes[i];
153			} else if (modes[i].hdisplay == hbest &&
154			    modes[i].vdisplay > vbest) {
155				vbest = modes[i].vdisplay;
156				mtemp = &modes[i];
157			}
158		}
159		aspect = mtemp->hdisplay * 100 / mtemp->vdisplay;
160		refresh = DIVIDE(DIVIDE(mtemp->dot_clock * 1000,
161		    mtemp->htotal), mtemp->vtotal);
162		if (mtemp != modes)
163			swap_modes(mtemp, modes);
164	}
165
166	/* Sort other modes by refresh rate, aspect ratio, then resolution */
167	for (j = 1; j < nmodes - 1; j++) {
168		rbest = 1000;
169		abest = 1000;
170		hbest = 0;
171		vbest = 0;
172		for (i = j; i < nmodes; i++) {
173			rtemp = abs(refresh -
174			    DIVIDE(DIVIDE(modes[i].dot_clock * 1000,
175			    modes[i].htotal), modes[i].vtotal));
176			atemp = (modes[i].hdisplay * 100 / modes[i].vdisplay);
177			if (rtemp < rbest) {
178				rbest = rtemp;
179				mtemp = &modes[i];
180			}
181			if (rtemp == rbest) {
182				/* Treat "close" aspect ratios as identical */
183				if (abs(abest - atemp) > (abest / 8) &&
184				    abs(aspect - atemp) < abs(aspect - abest)) {
185					abest = atemp;
186					mtemp = &modes[i];
187				}
188				if (atemp == abest ||
189				    abs(abest - atemp) <= (abest / 8)) {
190					if (modes[i].hdisplay > hbest) {
191						hbest = modes[i].hdisplay;
192						mtemp = &modes[i];
193					}
194					if (modes[i].hdisplay == hbest &&
195					    modes[i].vdisplay > vbest) {
196						vbest = modes[i].vdisplay;
197						mtemp = &modes[i];
198					}
199				}
200			}
201		}
202		if (mtemp != &modes[j])
203			swap_modes(mtemp, &modes[j]);
204	}
205}
206