245 lines
6.4 KiB
C
245 lines
6.4 KiB
C
/* pngpack: lossless image compression for a series of screen shots
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* Copyright (C) 2005-2009 Carsten Gnoerlich.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA,
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* or direct your browser at http://www.gnu.org.
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*/
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/stat.h>
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#include "pngio.h"
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#include "md5.h"
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#include "memory.h"
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/***
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*** aux stuff
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***/
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void FreeImage(Image *i)
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{
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if(i->image) free(i->image);
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if(i->file) fclose(i->file);
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if(i->row_pointers) free(i->row_pointers);
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if(i->png_read) png_destroy_read_struct(&i->png_read, &i->png_info, NULL);
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if(i->png_write) png_destroy_write_struct(&i->png_write, &i->png_info);
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free(i);
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}
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/***
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*** PNG reading
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***/
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Image *LoadPNG(char *name)
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{ struct MD5Context md5ctxt;
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struct stat mystat;
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Image *pi;
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png_byte *pb;
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unsigned char buf[256];
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unsigned int depth,size,i;
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png_color_16p background;
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fprintf(stdout,"Loading %s ... ", name);
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/* stat ppm file */
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if(stat(name, &mystat) == -1)
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{ fprintf(stdout, "COULD NOT STAT %s!\n", name);
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fflush(stdout);
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return NULL;
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}
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/* create image struct, really open */
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pi = calloc(1,sizeof(Image));
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if(!pi) Stop("out of memory for image");
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pi->name = name;
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pi->file = fopen(name, "rb");
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if(!pi->file)
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{ fprintf(stdout, "COULD NOT OPEN %s!\n", name);
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fflush(stdout);
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return NULL;
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}
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/* verify that we've got a png file */
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fread(buf, 1, 8, pi->file);
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if(png_sig_cmp(buf, 0, 8))
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{ fclose(pi->file);
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fprintf(stdout, "%s is not a .png file!\n", name);
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fflush(stdout);
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return NULL;
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}
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/* set up png data structs */
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pi->png_read = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
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pi->png_info = png_create_info_struct(pi->png_read);
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if(!pi->png_read || !pi->png_info)
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Stop("failed to initialize png structs");
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if(setjmp(png_jmpbuf(pi->png_read)))
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{ FreeImage(pi);
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fprintf(stdout, "error decoding .png file!\n");
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fflush(stdout);
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return NULL;
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}
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png_init_io(pi->png_read, pi->file);
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png_set_sig_bytes(pi->png_read, 8);
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/* read and evaluate info portion */
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png_read_info(pi->png_read, pi->png_info);
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pi->width = png_get_image_width(pi->png_read, pi->png_info);
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pi->height = png_get_image_height(pi->png_read, pi->png_info);
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depth = png_get_bit_depth(pi->png_read, pi->png_info);
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pi->channels = png_get_channels(pi->png_read, pi->png_info);
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fprintf(stdout, "%dx%d %s image",pi->width,pi->height,pi->channels==3?"RBG":"RBGA");
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if(depth != 8)
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{ FreeImage(pi);
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fprintf(stdout, ", ILLEGAL DEPTH: %d\n",depth);
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fflush(stdout);
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return NULL;
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}
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if(pi->channels == 3)
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png_set_filler(pi->png_read, 0, PNG_FILLER_AFTER);
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/* remember the png background color if there is one */
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if(png_get_bKGD(pi->png_read, pi->png_info, &background))
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pi->png_background = (background->red << 16) | (background->green << 8) | background->blue;
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else pi->png_background = 0;
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/* alloc memory for image */
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size = pi->width * pi->height;
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pi->bytesize = sizeof(unsigned int) * size;
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pi->image = malloc(pi->bytesize);
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if(!pi->image) Stop("out of memory for image");
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pi->row_pointers = malloc(sizeof(png_byte*) * pi->height);
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pb = (png_byte*)pi->image;
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for(i=0; i<pi->height; i++)
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{ pi->row_pointers[i] = pb;
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pb += pi->width*sizeof(unsigned int);
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}
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png_read_image(pi->png_read, pi->row_pointers);
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/* Clean up */
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fprintf(stdout,".\n");
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fflush(stdout);
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fclose(pi->file);
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png_destroy_read_struct(&pi->png_read, &pi->png_info, NULL);
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free(pi->row_pointers);
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/* calculate md5sum of image */
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MD5Init(&md5ctxt);
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MD5Update(&md5ctxt, (unsigned char*)pi->image, pi->bytesize);
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MD5Final(pi->checksum, &md5ctxt);
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return pi;
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}
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/***
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*** PNG writing
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***/
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void SavePNG(Image *pi, char *name)
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{ png_byte *pb;
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unsigned int i;
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png_color_16 background;
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/* open file */
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pi->file = fopen(name, "wb");
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if(!pi->file)
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Stop("Could not open %s: %s\n",name,strerror(errno));
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/* set up png data structs */
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pi->png_write = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
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pi->png_info = png_create_info_struct(pi->png_write);
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if(!pi->png_write || !pi->png_info)
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Stop("failed to initialize png structs");
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if(setjmp(png_jmpbuf(pi->png_write)))
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{ png_destroy_write_struct(&pi->png_write, &pi->png_info);
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fclose(pi->file);
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fprintf(stdout, "error creating .png file!\n");
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fflush(stdout);
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return;
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}
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png_init_io(pi->png_write, pi->file);
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/* supply image info to png library */
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png_set_compression_level(pi->png_write, Z_BEST_COMPRESSION);
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png_set_IHDR(pi->png_write, pi->png_info,
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pi->width, pi->height, 8,
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pi->channels == 4 ? PNG_COLOR_TYPE_RGB_ALPHA : PNG_COLOR_TYPE_RGB,
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PNG_INTERLACE_NONE,
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PNG_COMPRESSION_TYPE_DEFAULT,
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PNG_FILTER_TYPE_DEFAULT);
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background.red = (pi->png_background >> 16) & 0xff;
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background.green = (pi->png_background >> 8) & 0xff;
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background.blue = pi->png_background & 0xff;
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png_set_bKGD(pi->png_write, pi->png_info, &background);
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pi->row_pointers = malloc(sizeof(png_byte*) * pi->height);
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pb = (png_byte*)pi->image;
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for(i=0; i<pi->height; i++)
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{ pi->row_pointers[i] = pb;
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pb += pi->width*sizeof(unsigned int);
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}
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/* and write it out */
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png_write_info(pi->png_write, pi->png_info);
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if(pi->channels == 3)
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png_set_filler(pi->png_write, 0, PNG_FILLER_AFTER);
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png_write_image(pi->png_write, pi->row_pointers);
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png_write_end(pi->png_write, NULL);
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/* clean up */
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if(fclose(pi->file))
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Stop("Could not close %s: %s\n",name,strerror(errno));
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free(pi->row_pointers);
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png_destroy_write_struct(&pi->png_write, &pi->png_info);
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}
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