gd.c

来自「CA仿真模型中SLEUTH模型」· C语言 代码 · 共 2,537 行 · 第 1/4 页

 * fit in it exactly).  Use the VAX insv instruction to insert each
 * code in turn.  When the buffer fills up empty it and start over.
 */

static unsigned long cur_accum = 0;
static int cur_bits = 0;

static unsigned long masks[] = { 0x0000, 0x0001, 0x0003, 0x0007, 0x000F,
                                  0x001F, 0x003F, 0x007F, 0x00FF,
                                  0x01FF, 0x03FF, 0x07FF, 0x0FFF,
                                  0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF };

static void
output(code_int code)
{
    cur_accum &= masks[ cur_bits ];

    if( cur_bits > 0 )
        cur_accum |= ((long)code << cur_bits);
    else
        cur_accum = code;

    cur_bits += n_bits;

    while( cur_bits >= 8 ) {
        char_out( (unsigned int)(cur_accum & 0xff) );
        cur_accum >>= 8;
        cur_bits -= 8;
    }

    /*
     * If the next entry is going to be too big for the code size,
     * then increase it, if possible.
     */
   if ( free_ent > maxcode || clear_flg ) {

            if( clear_flg ) {

                maxcode = MAXCODE (n_bits = g_init_bits);
                clear_flg = 0;

            } else {

                ++n_bits;
                if ( n_bits == maxbits )
                    maxcode = maxmaxcode;
                else
                    maxcode = MAXCODE(n_bits);
            }
        }

    if( code == EOFCode ) {
        /*
         * At EOF, write the rest of the buffer.
         */
        while( cur_bits > 0 ) {
                char_out( (unsigned int)(cur_accum & 0xff) );
                cur_accum >>= 8;
                cur_bits -= 8;
        }

        flush_char();

        fflush( g_outfile );

        if( ferror( g_outfile ) )
		return;
    }
}

/*
 * Clear out the hash table
 */
static void
cl_block (void)             /* table clear for block compress */
{

        cl_hash ( (count_int) hsize );
        free_ent = ClearCode + 2;
        clear_flg = 1;

        output( (code_int)ClearCode );
}

static void
cl_hash(register count_int hsize)          /* reset code table */
                         
{

        register count_int *htab_p = htab+hsize;

        register long i;
        register long m1 = -1;

        i = hsize - 16;
        do {                            /* might use Sys V memset(3) here */
                *(htab_p-16) = m1;
                *(htab_p-15) = m1;
                *(htab_p-14) = m1;
                *(htab_p-13) = m1;
                *(htab_p-12) = m1;
                *(htab_p-11) = m1;
                *(htab_p-10) = m1;
                *(htab_p-9) = m1;
                *(htab_p-8) = m1;
                *(htab_p-7) = m1;
                *(htab_p-6) = m1;
                *(htab_p-5) = m1;
                *(htab_p-4) = m1;
                *(htab_p-3) = m1;
                *(htab_p-2) = m1;
                *(htab_p-1) = m1;
                htab_p -= 16;
        } while ((i -= 16) >= 0);

        for ( i += 16; i > 0; --i )
                *--htab_p = m1;
}

/******************************************************************************
 *
 * GIF Specific routines
 *
 ******************************************************************************/

/*
 * Number of characters so far in this 'packet'
 */
static int a_count;

/*
 * Set up the 'byte output' routine
 */
static void
char_init(void)
{
        a_count = 0;
}

/*
 * Define the storage for the packet accumulator
 */
static char accum[ 256 ];

/*
 * Add a character to the end of the current packet, and if it is 254
 * characters, flush the packet to disk.
 */
static void
char_out(int c)
{
        accum[ a_count++ ] = c;
        if( a_count >= 254 )
                flush_char();
}

/*
 * Flush the packet to disk, and reset the accumulator
 */
static void
flush_char(void)
{
        if( a_count > 0 ) {
                fputc( a_count, g_outfile );
                fwrite( accum, 1, a_count, g_outfile );
                a_count = 0;
        }
}

static void init_statics(void) {
	/* Some of these are properly initialized later. What I'm doing
		here is making sure code that depends on C's initialization
		of statics doesn't break when the code gets called more
		than once. */
	Width = 0;
	Height = 0;
	curx = 0;
	cury = 0;
	CountDown = 0;
	Pass = 0;
	Interlace = 0;
	a_count = 0;
	cur_accum = 0;
	cur_bits = 0;
	g_init_bits = 0;
	g_outfile = 0;
	ClearCode = 0;
	EOFCode = 0;
	free_ent = 0;
	clear_flg = 0;
	offset = 0;
	in_count = 1;
	out_count = 0;	
	hsize = HSIZE;
	n_bits = 0;
	maxbits = GIFBITS;
	maxcode = 0;
	maxmaxcode = (code_int)1 << GIFBITS;
}


/* +-------------------------------------------------------------------+ */
/* | Copyright 1990, 1991, 1993, David Koblas.  ([e-mail])    | */
/* |   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.           | */
/* +-------------------------------------------------------------------+ */


#define        MAXCOLORMAPSIZE         256

#define        TRUE    1
#define        FALSE   0

#define CM_RED         0
#define CM_GREEN       1
#define CM_BLUE                2

#define        MAX_LWZ_BITS            12

#define INTERLACE              0x40
#define LOCALCOLORMAP  0x80
#define BitSet(byte, bit)      (((byte) & (bit)) == (bit))

#define        ReadOK(file,buffer,len) (fread(buffer, len, 1, file) != 0)

#define LM_to_uint(a,b)                        (((b)<<8)|(a))

/* We may eventually want to use this information, but def it out for now */
#if 0
static struct {
       unsigned int    Width;
       unsigned int    Height;
       unsigned char   ColorMap[3][MAXCOLORMAPSIZE];
       unsigned int    BitPixel;
       unsigned int    ColorResolution;
       unsigned int    Background;
       unsigned int    AspectRatio;
} GifScreen;
#endif

static struct {
       int     transparent;
       int     delayTime;
       int     inputFlag;
       int     disposal;
} Gif89 = { -1, -1, -1, 0 };

static int ReadColorMap (FILE *fd, int number, unsigned char (*buffer)[256]);
static int DoExtension (FILE *fd, int label, int *Transparent);
static int GetDataBlock (FILE *fd, unsigned char *buf);
static int GetCode (FILE *fd, int code_size, int flag);
static int LWZReadByte (FILE *fd, int flag, int input_code_size);
static void ReadImage (gdImagePtr im, FILE *fd, int len, int height, unsigned char (*cmap)[256], int interlace, int ignore);

int ZeroDataBlock;

gdImagePtr
gdImageCreateFromGif(FILE *fd)
{
       int imageNumber;
       int BitPixel;
       int ColorResolution;
       int Background;
       int AspectRatio;
       int Transparent = (-1);
       unsigned char   buf[16];
       unsigned char   c;
       unsigned char   ColorMap[3][MAXCOLORMAPSIZE];
       unsigned char   localColorMap[3][MAXCOLORMAPSIZE];
       int             imw, imh;
       int             useGlobalColormap;
       int             bitPixel;
       int             imageCount = 0;
       char            version[4];
       gdImagePtr im = 0;
       ZeroDataBlock = FALSE;

       imageNumber = 1;
       if (! ReadOK(fd,buf,6)) {
		return 0;
	}
       if (strncmp((char *)buf,"GIF",3) != 0) {
		return 0;
	}
       strncpy(version, (char *)buf + 3, 3);
       version[3] = '\0';

       if ((strcmp(version, "87a") != 0) && (strcmp(version, "89a") != 0)) {
		return 0;
	}
       if (! ReadOK(fd,buf,7)) {
		return 0;
	}
       BitPixel        = 2<<(buf[4]&0x07);
       ColorResolution = (int) (((buf[4]&0x70)>>3)+1);
       Background      = buf[5];
       AspectRatio     = buf[6];

       if (BitSet(buf[4], LOCALCOLORMAP)) {    /* Global Colormap */
               if (ReadColorMap(fd, BitPixel, ColorMap)) {
			return 0;
		}
       }
       for (;;) {
               if (! ReadOK(fd,&c,1)) {
                       return 0;
               }
               if (c == ';') {         /* GIF terminator */
                       int i;
                       if (imageCount < imageNumber) {
                               return 0;
                       }
                       /* Terminator before any image was declared! */
                       if (!im) {
                              return 0;
                       }
		       /* Check for open colors at the end, so
                          we can reduce colorsTotal and ultimately
                          BitsPerPixel */
                       for (i=((im->colorsTotal-1)); (i>=0); i--) {
                               if (im->open[i]) {
                                       im->colorsTotal--;
                               } else {
                                       break;
                               }
                       } 
                       return im;
               }

               if (c == '!') {         /* Extension */
                       if (! ReadOK(fd,&c,1)) {
                               return 0;
                       }
                       DoExtension(fd, c, &Transparent);
                       continue;
               }

               if (c != ',') {         /* Not a valid start character */
                       continue;
               }

               ++imageCount;

               if (! ReadOK(fd,buf,9)) {
	               return 0;
               }

               useGlobalColormap = ! BitSet(buf[8], LOCALCOLORMAP);

               bitPixel = 1<<((buf[8]&0x07)+1);

               imw = LM_to_uint(buf[4],buf[5]);
               imh = LM_to_uint(buf[6],buf[7]);
	       if (!(im = gdImageCreate(imw, imh))) {
			 return 0;
	       }
               im->interlace = BitSet(buf[8], INTERLACE);
               if (! useGlobalColormap) {
                       if (ReadColorMap(fd, bitPixel, localColorMap)) { 
                                 return 0;
                       }
                       ReadImage(im, fd, imw, imh, localColorMap, 
                                 BitSet(buf[8], INTERLACE), 
                                 imageCount != imageNumber);
               } else {
                       ReadImage(im, fd, imw, imh,
                                 ColorMap, 
                                 BitSet(buf[8], INTERLACE), 
                                 imageCount != imageNumber);
               }
               if (Transparent != (-1)) {
                       gdImageColorTransparent(im, Transparent);
               }	   
       }
}

static int
ReadColorMap(FILE *fd, int number, unsigned char (*buffer)[256])
{
       int             i;
       unsigned char   rgb[3];


       for (i = 0; i < number; ++i) {
               if (! ReadOK(fd, rgb, sizeof(rgb))) {
                       return TRUE;
               }
               buffer[CM_RED][i] = rgb[0] ;
               buffer[CM_GREEN][i] = rgb[1] ;
               buffer[CM_BLUE][i] = rgb[2] ;
       }


       return FALSE;
}

static int
DoExtension(FILE *fd, int label, int *Transparent)
{
       static unsigned char     buf[256];

       switch (label) {
       case 0xf9:              /* Graphic Control Extension */
               (void) GetDataBlock(fd, (unsigned char*) buf);
               Gif89.disposal    = (buf[0] >> 2) & 0x7;
               Gif89.inputFlag   = (buf[0] >> 1) & 0x1;
               Gif89.delayTime   = LM_to_uint(buf[1],buf[2]);
               if ((buf[0] & 0x1) != 0)
                       *Transparent = buf[3];

               while (GetDataBlock(fd, (unsigned char*) buf) != 0)
                       ;
               return FALSE;
       default:
               break;
       }
       while (GetDataBlock(fd, (unsigned char*) buf) != 0)
               ;

       return FALSE;
}

static int
GetDataBlock(FILE *fd, unsigned char *buf)
{
       unsigned char   count;

       if (! ReadOK(fd,&count,1)) {
               return -1;
       }

       ZeroDataBlock = count == 0;

       if ((count != 0) && (! ReadOK(fd, buf, count))) {
               return -1;
       }

       return count;
}

static int
GetCode(FILE *fd, int code_size, int flag)
{
       static unsigned char    buf[280];
       static int              curbit, lastbit, done, last_byte;
       int                     i, j, ret;
       unsigned char           count;

       if (flag) {
               curbit = 0;
               lastbit = 0;
               done = FALSE;
               return 0;
       }

       if ( (curbit+code_size) >= lastbit) {
               if (done) {
                       if (curbit >= lastbit) {
                                /* Oh well */
                       }                        
                       return -1;
               }
               buf[0] = buf[last_byte-2];
               buf[1] = buf[last_byte-1];

               if ((count = GetDataBlock(fd, &buf[2])) == 0)
                       done = TRUE;

               last_byte = 2 + count;
               curbit = (curbit - lastbit) + 16;
               lastbit = (2+count)*8 ;
       }

       ret = 0;
       for (i = curbit, j = 0; j < code_size; ++i, ++j)
               ret |= ((buf[ i / 8 ] & (1 << (i % 8))) != 0) << j;

       curbit += code_size;

       return ret;
}

static int
LWZReadByte(FILE *fd, int flag, int input_code_size)
{
       static int      fresh = FALSE;
       int             code, incode;
       static int      code_size, set_code_size;
       static int      max_code, max_code_size;
       static int      firstcode, oldcode;
       static int      clear_code, end_code;
       static int      table[2][(1<< MAX_LWZ_BITS)];
       static int      stack[(1<<(MAX_LWZ_BITS))*2], *sp;
       register int    i;

       if (flag) {
               set_code_size = input_code_size;
               code_size = set_code_size+1;
               clear_code = 1 << set_code_size ;
               end_code = clear_code + 1;
               max_code_size = 2*clear_code;
               max_code = clear_code+2;

               GetCode(fd, 0, TRUE);
               
               fresh = TRUE;

               for (i = 0; i < clear_code; ++i) {
                       table[0][i] = 0;
                       table[1][i] = i;
               }
               for (; i < (1<<MAX_LWZ_BITS); ++i)
                       table[0][i] = table[1][0] = 0;

               sp = stack;

               return 0;
       } else if (fresh) {
               fresh = FALSE;
               do {
                       firstcode = oldcode =
                               GetCode(fd, code_size, FALSE);
               } while (firstcode == clear_code);
               return firstcode;
       }

       if (sp > stack)
               return *--sp;

       while ((code = GetCode(fd, code_size, FALSE)) >= 0) {
               if (code == clear_code) {
                       for (i = 0; i < clear_code; ++i) {
                               table[0][i] = 0;
                               table[1][i] = i;
                       }
                       for (; i < (1<<MAX_LWZ_BITS); ++i)
                               table[0][i] = table[1][i] = 0;
                       code_size = set_code_size+1;
                       max_code_size = 2*clear_code;
                       max_code = clear_code+2;
                       sp = stack;
                       firstcode = oldcode =
                                       GetCode(fd, code_size, FALSE);
                       return firstcode;
               } else if (code == end_code) {
                       int             count;
                       unsigned char   buf[260];

                       if (ZeroDataBlock)
                               return -2;

                       while ((count = GetDataBlock(fd, buf)) > 0)
                               ;

                       if (count != 0)
                       return -2;
               }

               incode = code;

               if (code >= max_code) {
                       *sp++ = firstcode;
                       code = oldcode;
               }

               while (code >= clear_code) {
                       *sp++ = table[1][code];
                       if (code == table[0][code]) {
                               /* Oh well */
                       }
                       code = table[0][code];
               }

               *sp++ = firstcode = table[1][code];

               if ((code = max_code) <(1<<MAX_LWZ_BITS)) {
                       table[0][code] = oldcode;
                       table[1][code] = firstcode;
                       ++max_code;
                       if ((max_code >= max_code_size) &&
                               (max_code_size < (1<<MAX_LWZ_BITS))) {
                               max_code_size *= 2;
                               ++code_size;
                       }
               }

               oldcode = incode;

               if (sp > stack)
                       return *--sp;
       }
       return code;
}

static void
ReadImage(gdImagePtr im, FILE *fd, int len, int height, unsigned char (*cmap)[256], int interlace, int ignore)
{
       unsigned char   c;      
       int             v;
       int             xpos = 0, ypos = 0, pass = 0;
       int i;
       /* Stash the color map into the image */
       for (i=0; (i<gdMaxColors); i++) {
               im->red[i] = cmap[CM_RED][i];	
               im->green[i] = cmap[CM_GREEN][i];	
               im->blue[i] = cmap[CM_BLUE][i];	
               im->open[i] = 1;
       }
       /* Many (perhaps most) of these colors will remain marked open. */
       im->colorsTotal = gdMaxColors;
       /*
       **  Initialize the Compression routines
       */
       if (! ReadOK(fd,&c,1)) {
               return; 
       }
       if (LWZReadByte(fd, TRUE, c) < 0) {
               return;
       }

       /*
       **  If this is an "uninteresting picture" ignore it.
       */
       if (ignore) {
               while (LWZReadByte(fd, FALSE, c) >= 0)
                       ;
               return;
       }

       while ((v = LWZReadByte(fd,FALSE,c)) >= 0 ) {
               /* This how we recognize which colors are actually used. */