rosapps/devutils/vgafontedit/fileformats.txt

   1 VGA Font File Formats
   2 =====================
   3
   4 We only deal with 8x8 fonts with 256 characters, so different formats aren't described here.
   5
   6 1. The binary format (*.bin)
   7 ----------------------------
   8 A binary font file is always 2048 bytes in size.
   9 These bytes are divided into 256 characters, so every character is 8 bytes large.
  10 Each byte represents a character row. Consequently, each column is represented by one bit. The most-significant bit contains the pixel of the first column from the left.
  11
  12 Example:
  13   We want to get the pixel in the third column of the second row of the seventh character.
  14   We assume you loaded the binary font file completely into a byte array called FontBits.
  15
  16   // All indexes need to be zero-based
  17   UINT uCharacter = 6;
  18   UINT uRow = 1;
  19   UINT uColumn = 2;
  20
  21   UCHAR uBit;
  22
  23   // uBit will either contain 0 (0-bit is set) or 128 dec, 0x80 hex (1-bit is set) now
  24   uBit = FontBits[uCharacter * 8 + uRow] << uColumn & 0x80;
  25
  26 2. The PC Screen Font Version 1 format (*.psf)
  27 ----------------------------------------------
  28 A PC Screen Font Version 1 file is always 2052 bytes in size.
  29
  30 It has the following structure:
  31
  32 struct PSF1_FILE
  33 {
  34     UCHAR uMagic[2];
  35     UCHAR uMode;
  36     UCHAR uCharSize;
  37
  38     UCHAR FontBits[2048];
  39 };
  40
  41 * uMagic contains two magic bytes, which identify a PSFv1 file. These are:
  42      uMagic[0] = 0x36
  43      uMagic[1] = 0x04
  44
  45 * uMode specifies special modes of the font.
  46   We only deal with fonts here, which don't have any special modes, so this value should be 0.
  47
  48 * uCharSize specifies the size of a character.
  49   In our case, this needs to be 8.
  50
  51 * Finally the FontBits array contains the font bits in the same format as described above.
  52   This way, it is very easy to convert a PSFv1 file to a binary *.bin file.
  53
  54
  55 - Colin Finck, 2008/02/01