1// Copyright (c) 2013 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "chromeos/display/output_util.h"
6
7#include <X11/extensions/Xrandr.h>
8#include <X11/Xatom.h>
9#include <X11/Xlib.h>
10
11#include "base/strings/string_util.h"
12#include "base/x11/edid_parser_x11.h"
13
14namespace chromeos {
15namespace {
16
17// Prefixes for the built-in displays.
18const char kInternal_LVDS[] = "LVDS";
19const char kInternal_eDP[] = "eDP";
20const char kInternal_DSI[] = "DSI";
21
22// Gets some useful data from the specified output device, such like
23// manufacturer's ID, product code, and human readable name. Returns false if it
24// fails to get those data and doesn't touch manufacturer ID/product code/name.
25// NULL can be passed for unwanted output parameters.
26bool GetOutputDeviceData(XID output,
27                         uint16* manufacturer_id,
28                         std::string* human_readable_name) {
29  unsigned long nitems = 0;
30  unsigned char *prop = NULL;
31  if (!base::GetEDIDProperty(output, &nitems, &prop))
32    return false;
33
34  bool result = base::ParseOutputDeviceData(
35      prop, nitems, manufacturer_id, human_readable_name);
36  XFree(prop);
37  return result;
38}
39
40}  // namespace
41
42std::string GetDisplayName(XID output_id) {
43  std::string display_name;
44  GetOutputDeviceData(output_id, NULL, &display_name);
45  return display_name;
46}
47
48bool GetOutputOverscanFlag(XID output, bool* flag) {
49  unsigned long nitems = 0;
50  unsigned char *prop = NULL;
51  if (!base::GetEDIDProperty(output, &nitems, &prop))
52    return false;
53
54  bool found = ParseOutputOverscanFlag(prop, nitems, flag);
55  XFree(prop);
56  return found;
57}
58
59bool ParseOutputOverscanFlag(const unsigned char* prop,
60                             unsigned long nitems,
61                             bool *flag) {
62  // See http://en.wikipedia.org/wiki/Extended_display_identification_data
63  // for the extension format of EDID.  Also see EIA/CEA-861 spec for
64  // the format of the extensions and how video capability is encoded.
65  //  - byte 0: tag.  should be 02h.
66  //  - byte 1: revision.  only cares revision 3 (03h).
67  //  - byte 4-: data block.
68  const unsigned int kExtensionBase = 128;
69  const unsigned int kExtensionSize = 128;
70  const unsigned int kNumExtensionsOffset = 126;
71  const unsigned int kDataBlockOffset = 4;
72  const unsigned char kCEAExtensionTag = '\x02';
73  const unsigned char kExpectedExtensionRevision = '\x03';
74  const unsigned char kExtendedTag = 7;
75  const unsigned char kExtendedVideoCapabilityTag = 0;
76  const unsigned int kPTOverscan = 4;
77  const unsigned int kITOverscan = 2;
78  const unsigned int kCEOverscan = 0;
79
80  if (nitems <= kNumExtensionsOffset)
81    return false;
82
83  unsigned char num_extensions = prop[kNumExtensionsOffset];
84
85  for (size_t i = 0; i < num_extensions; ++i) {
86    // Skip parsing the whole extension if size is not enough.
87    if (nitems < kExtensionBase + (i + 1) * kExtensionSize)
88      break;
89
90    const unsigned char* extension = prop + kExtensionBase + i * kExtensionSize;
91    unsigned char tag = extension[0];
92    unsigned char revision = extension[1];
93    if (tag != kCEAExtensionTag || revision != kExpectedExtensionRevision)
94      continue;
95
96    unsigned char timing_descriptors_start =
97        std::min(extension[2], static_cast<unsigned char>(kExtensionSize));
98    const unsigned char* data_block = extension + kDataBlockOffset;
99    while (data_block < extension + timing_descriptors_start) {
100      // A data block is encoded as:
101      // - byte 1 high 3 bits: tag. '07' for extended tags.
102      // - byte 1 remaining bits: the length of data block.
103      // - byte 2: the extended tag.  '0' for video capability.
104      // - byte 3: the capability.
105      unsigned char tag = data_block[0] >> 5;
106      unsigned char payload_length = data_block[0] & 0x1f;
107      if (static_cast<unsigned long>(data_block + payload_length - prop) >
108          nitems)
109        break;
110
111      if (tag != kExtendedTag || payload_length < 2) {
112        data_block += payload_length + 1;
113        continue;
114      }
115
116      unsigned char extended_tag_code = data_block[1];
117      if (extended_tag_code != kExtendedVideoCapabilityTag) {
118        data_block += payload_length + 1;
119        continue;
120      }
121
122      // The difference between preferred, IT, and CE video formats
123      // doesn't matter. Sets |flag| to true if any of these flags are true.
124      if ((data_block[2] & (1 << kPTOverscan)) ||
125          (data_block[2] & (1 << kITOverscan)) ||
126          (data_block[2] & (1 << kCEOverscan))) {
127        *flag = true;
128      } else {
129        *flag = false;
130      }
131      return true;
132    }
133  }
134
135  return false;
136}
137
138bool IsInternalOutputName(const std::string& name) {
139  return name.find(kInternal_LVDS) == 0 || name.find(kInternal_eDP) == 0 ||
140      name.find(kInternal_DSI) == 0;
141}
142
143const XRRModeInfo* FindXRRModeInfo(const XRRScreenResources* screen_resources,
144                                   XID current_mode) {
145  for (int m = 0; m < screen_resources->nmode; m++) {
146    XRRModeInfo *mode = &screen_resources->modes[m];
147    if (mode->id == current_mode)
148      return mode;
149  }
150  return NULL;
151}
152
153namespace test {
154
155XRRModeInfo CreateModeInfo(int id,
156                           int width,
157                           int height,
158                           bool interlaced,
159                           float refresh_rate) {
160  XRRModeInfo mode_info = {0};
161  mode_info.id = id;
162  mode_info.width = width;
163  mode_info.height = height;
164  if (interlaced)
165    mode_info.modeFlags = RR_Interlace;
166  if (refresh_rate != 0.0f) {
167    mode_info.hTotal = 1;
168    mode_info.vTotal = 1;
169    mode_info.dotClock = refresh_rate;
170  }
171  return mode_info;
172}
173
174}  // namespace test
175
176}  // namespace chromeos
177