/*
  chars.c - Display the character set.

  Display characters with or without their numbers, using decimal, hex or both.
  Accepts only one argument:

    d: use decimal numbers (default)
    x: use hexadecimal numbers
    l: both dec and hex numbers, characters 0 to 127
    h: both dec and hex numbers, characters 128 to 255
    a: both dec and hex numbers, all characters
    c: characters only
    s: characters only, space in-between

  Jason Hood, 30 October, 1998.
  Public Domain.

  14 & 15 October, 2003, v1.00:
    recognise current background color;
    use normal output if redirected.
*/

#define PVERS "1.00"
#define PDATE "15 October, 2003"


#include <stdio.h>
#include <io.h>


void disp_char( int chr, int attr );
int  get_bkgd( void );
void help( char* program );


#define LOW   1
#define HIGH  2
#define ALL   3
#define CHARS 4
#define SPACE 5

#define FIRST  15		// Display characters in alternating colors:
#define SECOND 10		//  bright white and bright green
#define SWITCH (FIRST ^ SECOND)


int redir;			// Non-zero if output has been redirected


int main( int argc, char* argv[] )
{
  int dec = 0,
      hex = 0,
      fmt = 0,
      both;
  int beg, end, wid;
  int color = FIRST;
  int j, k;

  if (argc > 1)
  {
    j = 0;
    if (argv[1][0] == '-' || argv[1][0] == '/')
      ++j;
    switch (argv[1][j] | 0x20)
    {
      case 'd': dec = 1;     break;
      case 'x': hex = 1;     break;
      case 'l': fmt = LOW;   break;
      case 'h': fmt = HIGH;  break;
      case 'a': fmt = ALL;   break;
      case 'c': fmt = CHARS; break;
      case 's': fmt = SPACE; break;

      default:
	help( argv[0] );
	return 0;
    }
  }
  if (!dec && !hex && !fmt)
    dec = 1;
  both = (fmt == LOW || fmt == HIGH || fmt == ALL);
  if (both)
    dec = hex = 1;

  beg = (fmt == HIGH) ? 128 : 0;
  end = (fmt == LOW)  ? 127 : 255;
  wid = (fmt == 0) ? 13 : (both) ? 8 : 32;

  redir = !isatty( 1 );
  if (!redir)
  {
    putchar( '\n' );
    color |= get_bkgd();
  }
  else if (beg == 0)
    beg = 32;

  k = 0;
  for (j = beg; j <= end; ++j)
  {
    if (dec)
      printf( "%3d ",   j );
    if (hex)
    {
      if (!dec)
	putchar( ' ' );
      printf( "%02x ", j );
    }
    disp_char( j, color );

    color ^= SWITCH;
    if (++k == wid)
    {
      k = 0;
      putchar( '\n' );
      if (fmt != 0)
	color ^= SWITCH;
    }
    else if (fmt != CHARS)
    {
      putchar( ' ' );
      if (both)
	putchar( ' ' );
    }
  }
  if (fmt == 0)
    putchar( '\n' );

  return 0;
}


// Display a character using Video BIOS.
// Increases cursor position, but does not wrap.
void disp_char( int chr, int attr )
{
  if (redir)
    putchar( chr );
  else
  asm {
    mov bh, 0				// I'll assume page 0
    mov ah, 3				// Get Cursor Position
    int 0x10
    mov ah, 0x09			// Display Character
    mov al, byte ptr chr		// Get the character
    mov bl, byte ptr attr		//  and attribute
    mov cx, 1				// Just the one
    int 0x10
    inc dl				// Next column
    mov ah, 2				// Set Cursor Position
    int 0x10
  }
}


// Determine the background color.
int  get_bkgd( void )
{
  fputs( " \b", stdout );
  asm {
    mov bh, 0				// I'll assume page 0
    mov ah, 8				// Get Char and Attr at Cursor Position
    int 0x10
    and ah, 0xf0			// Strip off foreground
  }
  return _AH;
}


void help( char* program )
{
  printf(
"Characters by Jason Hood <jadoxa@yahoo.com.au>.\n"
"Version "PVERS" ("PDATE"). Public Domain.\n"
"http://misc.adoxa.cjb.net/\n"
"\n"
"Display the current character set, with or without character codes.\n"
"\n"
"Usage: %s [-|/][d | x | l | h | a | c | s]\n"
"\n"
"  d: use decimal numbers (default)\n"
"  x: use hexadecimal numbers\n"
"  l: both dec and hex numbers, characters 0 to 127\n"
"  h: both dec and hex numbers, characters 128 to 255\n"
"  a: both dec and hex numbers, all characters\n"
"  c: characters only\n"
"  s: characters only, space in-between\n"
  , program );
}