The Datafile PD-CD 4/DATAFILE_PDCD4.iso/utilities/utilsm/netpbmsca/ppm/c/spctoppm

Text File | 1993-10-04 | 4.3 KB | 213 lines

/* 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;
    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] );
    }

#if __STDC__
static void
DoChar( int n, char c )
#else /*__STDC__*/
static void
DoChar( n, c )
    int n;
    char c;
#endif /*__STDC__*/
    {
    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 ) );
            }
        }
    }