gd_gif_in.c

php-4.4.7学习linux时下载的源代码

static int
GetDataBlock(gdIOCtx *fd, unsigned char *buf)
{
	int rv;
	int i;
	char *tmp = NULL;
	
	rv = GetDataBlock_(fd,buf);
	if (VERBOSE) {
		if (rv > 0) {
			tmp = safe_emalloc(3 * rv, sizeof(char), 1);
			for (i=0;i<rv;i++) {
				sprintf(&tmp[3*sizeof(char)*i], " %02x", buf[i]);
			}
		} else {
			tmp = estrdup("");
		}
		php_gd_error_ex(E_NOTICE, "[GetDataBlock returning %d: %s]", rv, tmp);
		efree(tmp);
	}
	return(rv);
}

static int
GetCode_(gdIOCtx *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
GetCode(gdIOCtx *fd, int code_size, int flag)
{
 int rv;

 rv = GetCode_(fd,code_size,flag);
 if (VERBOSE) php_gd_error_ex(E_NOTICE, "[GetCode(,%d,%d) returning %d]\n",code_size,flag,rv);
 return(rv);
}

#define STACK_SIZE ((1<<(MAX_LWZ_BITS))*2)
static int
LWZReadByte_(gdIOCtx *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[STACK_SIZE], *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 (sp == (stack + STACK_SIZE)) {
		       /* Bad compressed data stream */
		       return -1;
	       }

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

               while (code >= clear_code) {
		       if (sp == (stack + STACK_SIZE)) {
			       /* Bad compressed data stream */
			       return -1;
		       }
                       *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 int
LWZReadByte(gdIOCtx *fd, int flag, int input_code_size)
{
 int rv;

 rv = LWZReadByte_(fd,flag,input_code_size);
 if (VERBOSE) php_gd_error_ex(E_NOTICE, "[LWZReadByte(,%d,%d) returning %d]\n",flag,input_code_size,rv);
 return(rv);
}

static void
ReadImage(gdImagePtr im, gdIOCtx *fd, int len, int height, unsigned char (*cmap)[256], int interlace) /*1.4//, int ignore) */
{
       unsigned char   c;      
       int             v;
       int             xpos = 0, ypos = 0, pass = 0;
       int i;

	   /*
		**  Initialize the Compression routines
		*/
	   if (! ReadOK(fd,&c,1)) {
		   return;
	   }

	   if (c > MAX_LWZ_BITS) {
		   return;	
	   }


       /* 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;

       if (LWZReadByte(fd, TRUE, c) < 0) {
               return;
       }

       /*
       **  If this is an "uninteresting picture" ignore it.
       **  REMOVED For 1.4
       */
       /*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. */
               if (im->open[v]) {
                       im->open[v] = 0;
               }
               gdImageSetPixel(im, xpos, ypos, v);
               ++xpos;
               if (xpos == len) {
                       xpos = 0;
                       if (interlace) {
                               switch (pass) {
                               case 0:
                               case 1:
                                       ypos += 8; break;
                               case 2:
                                       ypos += 4; break;
                               case 3:
                                       ypos += 2; break;
                               }

                               if (ypos >= height) {
                                       ++pass;
                                       switch (pass) {
                                       case 1:
                                               ypos = 4; break;
                                       case 2:
                                               ypos = 2; break;
                                       case 3:
                                               ypos = 1; break;
                                       default:
                                               goto fini;
                                       }
                               }
                       } else {
                               ++ypos;
                       }
               }
               if (ypos >= height)
                       break;
       }

fini:
       if (LWZReadByte(fd,FALSE,c)>=0) {
               /* Ignore extra */
       }
}