src/system/boot/loader/pager.cpp

   1 /*
   2  * Copyright 2010, Ingo Weinhold, ingo_weinhold@gmx.de.
   3  * Distributed under the terms of the MIT License.
   4  */
   5
   6
   7 #include "pager.h"
   8
   9 #include <ctype.h>
  10 #include <string.h>
  11
  12 #include <algorithm>
  13
  14 #include <boot/platform/generic/text_console.h>
  15
  16
  17 // #pragma mark - PagerTextSource
  18
  19
  20 PagerTextSource::~PagerTextSource()
  21 {
  22 }
  23
  24
  25 // #pragma mark -
  26
  27
  28 static size_t
  29 next_line(const PagerTextSource& textSource, size_t width, size_t offset,
  30         char* buffer, size_t bufferSize)
  31 {
  32         size_t bytesRead = textSource.Read(offset, buffer, bufferSize - 1);
  33         if (bytesRead == 0)
  34                 return 0;
  35
  36         buffer[bytesRead] = '\0';
  37
  38         // replace all '\0's by spaces
  39         for (size_t i = 0; i < bytesRead; i++) {
  40                 if (buffer[i] == '\0')
  41                         buffer[i] = ' ';
  42         }
  43
  44         if (const char* lineEnd = strchr(buffer, '\n'))
  45                 bytesRead = lineEnd - buffer;
  46
  47         if (bytesRead > (size_t)width)
  48                 bytesRead = width;
  49
  50         // replace unprintables by '.'
  51         for (size_t i = 0; i < bytesRead; i++) {
  52                 if (!isprint(buffer[i]))
  53                         buffer[i] = '.';
  54         }
  55
  56         bool lineBreak = buffer[bytesRead] == '\n';
  57
  58         buffer[bytesRead] = '\0';
  59
  60         return bytesRead + (lineBreak ? 1 : 0);
  61 }
  62
  63
  64 static int32
  65 count_lines(const PagerTextSource& textSource, size_t width, char* buffer,
  66         size_t bufferSize)
  67 {
  68         int32 lineCount = 0;
  69         size_t offset = 0;
  70
  71         while (true) {
  72                 size_t bytesRead = next_line(textSource, width, offset, buffer,
  73                         bufferSize);
  74                 if (bytesRead == 0)
  75                         break;
  76
  77                 offset += bytesRead;
  78                 lineCount++;
  79         }
  80
  81         return lineCount;
  82 }
  83
  84
  85 static size_t
  86 offset_of_line(const PagerTextSource& textSource, size_t width, char* buffer,
  87         size_t bufferSize, int32 line)
  88 {
  89         int32 lineCount = 0;
  90         size_t offset = 0;
  91
  92         while (true) {
  93                 if (line == lineCount)
  94                         return offset;
  95
  96                 size_t bytesRead = next_line(textSource, width, offset, buffer,
  97                         bufferSize);
  98                 if (bytesRead == 0)
  99                         break;
 100
 101                 offset += bytesRead;
 102                 lineCount++;
 103         }
 104
 105         return offset;
 106 }
 107
 108
 109 // #pragma mark -
 110
 111
 112 void
 113 pager(const PagerTextSource& textSource)
 114 {
 115         console_set_cursor(0, 0);
 116
 117         int32 width = console_width();
 118         int32 height = console_height();
 119
 120         char lineBuffer[256];
 121
 122         int32 lineCount = count_lines(textSource, width, lineBuffer,
 123                 sizeof(lineBuffer));
 124         int32 topLine = 0;
 125
 126         bool quit = false;
 127         while (!quit) {
 128                 // get the text offset for the top line
 129                 size_t offset = offset_of_line(textSource, width, lineBuffer,
 130                         sizeof(lineBuffer), topLine);
 131
 132                 // clear the screen and print the lines
 133                 console_clear_screen();
 134
 135                 int32 screenLine = 0;
 136                 while (screenLine + 1 < height) {
 137                         size_t bytesRead = next_line(textSource, width, offset, lineBuffer,
 138                                 sizeof(lineBuffer));
 139                         if (bytesRead == 0)
 140                                 break;
 141
 142                         console_set_cursor(0, screenLine);
 143                         puts(lineBuffer);
 144
 145                         offset += bytesRead;
 146                         screenLine++;
 147                 }
 148
 149                 // print the statistics line at the bottom
 150                 console_set_cursor(0, height - 1);
 151                 console_set_color(BLACK, GRAY);
 152                 int32 bottomLine = std::min(topLine + height - 2, lineCount - 1);
 153                 printf("%" B_PRIuSIZE " - %" B_PRIuSIZE "  %" B_PRIuSIZE "%%",
 154                         topLine, bottomLine, (bottomLine + 1) * 100 / lineCount);
 155                 console_set_color(WHITE, BLACK);
 156
 157                 // wait for a key that changes the position
 158                 int32 previousTopLine = topLine;
 159
 160                 while (!quit && topLine == previousTopLine) {
 161                         switch (console_wait_for_key()) {
 162                                 case TEXT_CONSOLE_KEY_ESCAPE:
 163                                 case 'q':
 164                                 case 'Q':
 165                                         // quit
 166                                         quit = true;
 167                                         break;
 168
 169                                 case TEXT_CONSOLE_KEY_DOWN:
 170                                 case TEXT_CONSOLE_KEY_RETURN:
 171                                         // next line
 172                                         topLine++;
 173                                         break;
 174
 175                                 case TEXT_CONSOLE_KEY_UP:
 176                                         // previous line
 177                                         topLine--;
 178                                         break;
 179
 180                                 case TEXT_CONSOLE_KEY_PAGE_UP:
 181                                         // previous page
 182                                         topLine -= height - 1;
 183                                         break;
 184
 185                                 case TEXT_CONSOLE_KEY_PAGE_DOWN:
 186                                         // next page
 187                                         topLine += height - 1;
 188                                         break;
 189
 190                                 case TEXT_CONSOLE_KEY_HOME:
 191                                         // beginning of text
 192                                         topLine = 0;
 193                                         break;
 194
 195                                 case TEXT_CONSOLE_KEY_END:
 196                                         // end of text
 197                                         topLine = lineCount;
 198                                         break;
 199                         }
 200
 201                         if (topLine > lineCount - (height - 1))
 202                                 topLine = lineCount - (height - 1);
 203                         if (topLine < 0)
 204                                 topLine = 0;
 205                 }
 206         }
 207 }