/* tass_dos.1  -- first include file for DOS */



#ifdef __WATCOMC__
/* inline assembly language is a pain in the neck with Watcom C: it requires */
/* a ton of compiler-specific code; may its author slip on a banana peel!!!! */
#else
/* assembly source pragma: replace "asm" by whatever works on your compiler */
/* it often is __asm__, by the way */
#define ASM     asm
#endif



typedef union { void *A;     /* to convert addresses into offset, segment */
                long B;      /* to convert longs into hiword, loword */
                uint W[2];   /* W[0] : offset, W[1] : segment */
              } VideoRec;

typedef struct { uint mode;     /* video mode */
                 uint horpix;   /* pixels per horizontal line */
                 uint verlin;   /* rows of pixels per screen */
                 uint colors;   /* number of displayable colors, must be 16 */
               } video;

typedef byte Palette[65];    /* 65 bytes/palette: 17 for EGA colors & border */
                             /* + 16*3 = 48 for 16 DAC registers VGA & SVGA  */



/* global tables for DOS */

static byte logLUT[256] =      /* look-up table for log intensity display */
{
   0,  1,  2,  3,  4,  5,  6,  6,  6,  7,  7,  7,  7,  8,  8,  8,
   8,  8,  8,  8,  9,  9,  9,  9,  9,  9,  9,  9, 10, 10, 10, 10,
  10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11,
  11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12,
  12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
  12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
  13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
  13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14,
  14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
  14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
  14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
  14, 14, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
  15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
  15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
  15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
  15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15
};

static byte BitMask[4] = { 1, 2, 4, 8 };        /* 4 bit planes = 16 colors */

static Palette G16Pal =                         /* our own color palette */
{
  /* 16 colors palette registers */
      0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15,
  /* 1 border (overscan) palette register */
      7,
  /* 16 colors times 3 DAC registers: R, G, B */
      0,  0,  0,
      4,  4,  4,
      8,  8,  8,
     12, 12, 12,
     17, 17, 17,
     21, 21, 21,
     25, 25, 25,
     29, 29, 29,
     34, 34, 34,
     38, 38, 38,
     42, 42, 42,
     46, 46, 46,
     51, 51, 51,
     55, 55, 55,
     59, 59, 59,
     63, 63, 63
};



/* global variables for DOS */

static byte DacReg;             /* current DAC Color Page */
static byte OldMod;             /* former video mode */
static uint OldCur;             /* former cursor status */
static Palette OldPal;          /* former color palette */
static uint CRTC;               /* address of CRTC */

static BitLine bitplane[4];     /* 4 bit planes = 16 colors */

static video Video;             /* video mode specs */
static void *afont;             /* address of our 8 by 16 font */

static uint rowsiz;             /* # of bytes per row */
static uint rowlin;             /* # of lines per character row, must be 16 */
static uint maxrow;             /* # of rows per screen */