kernel/io/console/vga.cc

   1 // io/console/vga.cc -- Kernel debugging console for standard VGA text mode
   2 //
   3 // This software is copyright (c) 2006 Scott Wood <scott@buserror.net>.
   4 //
   5 // This software is provided 'as-is', without any express or implied warranty.
   6 // In no event will the authors or contributors be held liable for any damages
   7 // arising from the use of this software.
   8 //
   9 // Permission is hereby granted to everyone, free of charge, to use, copy,
  10 // modify, prepare derivative works of, publish, distribute, perform,
  11 // sublicense, and/or sell copies of the Software, provided that the above
  12 // copyright notice and disclaimer of warranty be included in all copies or
  13 // substantial portions of this software.
  14
  15 #include <System/IO.h>
  16 #include <kern/kernel.h>
  17 #include <kern/console.h>
  18 #include <kern/notifier.h>
  19 #include <kern/io.h>
  20 #include <kern/libc.h>
  21 #include <kern/addrs.h>
  22 #include <util/lock.h>
  23
  24 namespace IO {
  25 namespace Console {
  26         class VGA : public Console {
  27                 Lock::SpinLock lock;
  28
  29                 u16 *mem_base;
  30                 unsigned long io_base;
  31
  32                 int line_width;
  33                 int lines;
  34                 int pos;
  35
  36                 void putc(int ch, int attr)
  37                 {
  38                         if (ch == '\n') {
  39                                 pos += line_width;
  40                                 pos -= pos % line_width;
  41                         } else if (ch == '\r') {
  42                                 pos -= pos % line_width;
  43                         } else {
  44                                 // Use ll_swap_le16 rather than store_le16 in the hopes
  45                                 // that the compiler can simply change the shifts around
  46                                 // rather than assembling it one way and then ll_swapping.
  47                                 //
  48                                 // It's done as one atomic store rather than two single
  49                                 // byte writes (which would eliminate endianness concerns)
  50                                 // to eliminate the possibility of a race where the video
  51                                 // card reads a character before its attribute has been
  52                                 // written.
  53
  54                                 mem_base[pos++] = ll_swap_le16(ch | (attr << 8));
  55                         }
  56
  57                         if (pos >= lines * line_width) {
  58                                 pos -= line_width;
  59
  60                                 // FIXME: until memcpy is more than a stupid byte-at-a-time
  61                                 // loop, this could race with the video card.
  62
  63                                 memcpy(mem_base, mem_base + line_width,
  64                                        line_width * (lines - 1) * sizeof(u16));
  65
  66                                 for (int i = 0; i < line_width; i++)
  67                                         mem_base[pos + i] = ll_swap_le16(' ' | (7 << 8));
  68                         }
  69                 }
  70
  71                 void get_cursor()
  72                 {
  73                         ll_out_8(0x3d4, 14);
  74                         pos = (u16)ll_in_8(0x3d5) << 8;
  75                         ll_out_8(0x3d4, 15);
  76                         pos |= ll_in_8(0x3d5);
  77                 }
  78
  79                 void set_cursor()
  80                 {
  81                         ll_out_8(0x3d4, 14);
  82                         ll_out_8(0x3d5, pos >> 8);
  83                         ll_out_8(0x3d4, 15);
  84                         ll_out_8(0x3d5, pos & 0xff);
  85                 }
  86
  87         public:
  88                 #include <servers/io/console/vga/IO/Console/VGA.h>
  89
  90                 VGA()
  91                 {
  92                         init_iface();
  93
  94                         // FIXME: should be PCI mem space, not phys mem.
  95                         mem_base = (u16 *)Arch::phys_to_kvirt(0xb8000);
  96                         io_base = 0x3d0;
  97
  98                         // FIXME: detect
  99                         line_width = 80;
 100                         lines = 25;
 101
 102                         primary_console = this;
 103                 }
 104
 105                 void write(Array<octet> buf, u64 *LEN)
 106                 {
 107                         if (!valid_size_t(*LEN))
 108                                 /* throw something */
 109                                 return;
 110
 111                         size_t len = *LEN;
 112
 113                         if (len > buf.count)
 114                                 /* throw something */
 115                                 return;
 116
 117                         Lock::AutoSpinLockRecIRQ autolock(lock);
 118                         get_cursor();
 119
 120                         for (size_t i = 0; i < len; i++)
 121                                 putc(buf.ptr[i], 7);
 122
 123                         set_cursor();
 124                 }
 125
 126                 void write_async(Array<octet> buf, u64 len, Notifier notifier)
 127                 {
 128                         write(buf, &len);
 129                         io_notify(notifier, len, io_result::Success);
 130                 }
 131         };
 132
 133         // Use a static constructor, so that it can be used before
 134         // memory management is up and running.
 135
 136         VGA vga;
 137 }
 138 }
 139
 140 #include <servers/io/console/vga/footer.cc>