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/* spctoppm.c - read a compressed Spectrum file and produce a portable pixmap
**
** Copyright (C) 1991 by Steve Belczyk and Jef Poskanzer
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation. This software is provided "as is" without express or
** implied warranty.
*/
#include "ppm.h"
#define ROWS 200
#define COLS 320
#define MAXVAL 7
static void DoBitmap ARGS(( FILE* ifp ));
static void DoChar ARGS(( int n, char c ));
static void DoColormap ARGS(( FILE* ifp ));
static char screen[ROWS*COLS/2];
static short sscreen[ROWS*COLS/4];
static pixel pal[ROWS][48];
static long colormap_length, bitmap_length;
int
main( argc, argv )
int argc;
char* argv[];
{
FILE* ifp;
char c1, c2;
pixel* pixelrow;
register pixel* pP;
int row, col;
ppm_init( &argc, argv );
/* Check args. */
if ( argc > 2 )
pm_usage( "[spcfile]" );
if ( argc == 2 )
ifp = pm_openr( argv[1] );
else
ifp = stdin;
/* Check SPC file header. */
c1 = getc( ifp );
c2 = getc( ifp );
if ( ( c1 != 'S' ) || ( c2 != 'P' ) )
pm_error( "not a Spectrum picture" );
/* Skip reserved bytes. */
getc( ifp );
getc( ifp );
/* Get length of bitmap data. */
(void) pm_readbiglong( ifp, &bitmap_length );
/* and colormap */
(void) pm_readbiglong( ifp, &colormap_length );
/* Process bitmap. */
DoBitmap( ifp );
/* Process colormap. */
DoColormap( ifp );
pm_close( ifp );
/* Write the PPM file. */
ppm_writeppminit( stdout, COLS, ROWS, (pixval) MAXVAL, 0 );
pixelrow = ppm_allocrow( COLS );
for ( row = 0; row < ROWS; ++row )
{
for ( col = 0, pP = pixelrow; col < COLS; ++col, ++pP )
{
int c, ind, b, plane, x1;
/* Compute pixel value. */
ind = ( 80 * row ) + ( ( col >> 4 ) << 2 );
b = 0x8000 >> (col & 0xf);
c = 0;
for ( plane = 0; plane < 4; ++plane )
if ( b & sscreen[ind+plane] )
c |= (1 << plane);
/* Compute palette index. */
x1 = 10 * c;
if ( c & 1 )
x1 -= 5;
else
++x1;
if ( ( col >= x1 ) && ( col < ( x1 + 160 ) ) )
c += 16;
if ( col >= ( x1 + 160 ) )
c += 32;
/* Store the proper color. */
*pP = pal[row][c];
}
ppm_writeppmrow( stdout, pixelrow, COLS, (pixval) MAXVAL, 0 );
}
pm_close( stdout );
exit( 0 );
}
static void
DoBitmap( ifp )
FILE* ifp;
{
int i;
long count, data;
signed char h, c;
/* Zero out first scan line. */
for ( i = 0; i < 160; ++i )
screen[i] = 0;
/* 'count' counts number of input bytes. */
count = 0;
/* 'data' counts just data bytes. */
data = 0;
while ( count < bitmap_length )
{
/* Get next record header. */
h = getc( ifp );
++count;
if ( ( h >= 0 ) && ( count < bitmap_length ) )
{
for ( i = 0; i <= h; ++i )
{
c = getc( ifp );
++count;
DoChar( data, c );
++data;
}
}
else if ( ( h < 0 ) && ( count < bitmap_length ) )
{
c = getc( ifp );
++count;
for ( i = 0; i < ( 2 - h ); ++i )
{
DoChar( data, c );
++data;
}
}
}
/* Convert the char version of the screen to short. */
for ( i = 0; i < ROWS*COLS/4; ++i )
sscreen[i] = ( screen[i<<1] << 8 ) + ( 0xff & screen[(i<<1)+1] );
}
static void
DoChar( int n, char c )
{
int i;
/* Compute screen index. */
i = 160 + 2 * ( n / 7960 ) + 8 * ( ( n % 7960 ) / 2 ) + ( n & 1 );
screen[i] = c;
}
static void
DoColormap( ifp )
FILE* ifp;
{
int i, j, b;
short mask;
/* Clear first three palettes. */
for ( j = 0; j < 48; ++j )
PPM_ASSIGN( pal[0][j], 0, 0, 0 );
/* Read the palettes. */
for ( i = 1; i < ROWS; ++i )
for ( j = 0; j < 3; ++j )
{
(void) pm_readbigshort( ifp, &mask );
for ( b = 0; b < 15; ++b )
if ( mask & ( 1 << b ) )
{
short k;
(void) pm_readbigshort( ifp, &k );
PPM_ASSIGN( pal[i][(j*16)+b],
( k & 0x700 ) >> 8,
( k & 0x070 ) >> 4,
( k & 0x007 ) );
}
}
}
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