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<!DOCTYPE HTML PUBLIC "html.dtd"><HTML><HEAD><TITLE>The Data Compression Book-:Appendix B: Test Programs</TITLE><META NAME="ROBOTS" CONTENT="NOINDEX, NOFOLLOW"><SCRIPT><!--function displayWindow(url, width, height) { var Win = window.open(url,"displayWindow",'width=' + width +',height=' + height + ',resizable=1,scrollbars=yes');}//--></SCRIPT></HEAD><BODY BGCOLOR="#FFFFFF" VLINK="#DD0000" TEXT="#000000" LINK="#DD0000" ALINK="#FF0000"><TD WIDTH="540" VALIGN="TOP"><!-- <CENTER><TABLE><TR><TD><FORM METHOD="GET" ACTION="http://search.itknowledge.com/excite/cgi-bin/AT-foldocsearch.cgi"><INPUT NAME="search" SIZE="20" VALUE=""><BR><CENTER><INPUT NAME="searchButton" TYPE="submit" VALUE="Glossary Search"></CENTER><INPUT NAME="source" TYPE="hidden" VALUE="local" CHECKED> <INPUT NAME="bltext" TYPE="hidden" VALUE="Back to Search"><INPUT NAME="sp" TYPE="hidden" VALUE="sp"></FORM></TD><TD><IMG SRC="http://www.itknowledge.com/images/dotclear.gif" WIDTH="15" HEIGHT="1"></TD><TD><FORM METHOD="POST" ACTION="http://search.itknowledge.com/excite/cgi-bin/AT-subscriptionsearch.cgi"><INPUT NAME="search" SIZE="20" VALUE=""><BR><CENTER><INPUT NAME="searchButton" TYPE="submit" VALUE=" Book Search "></CENTER><INPUT NAME="source" TYPE="hidden" VALUE="local" CHECKED> <INPUT NAME="backlink" TYPE="hidden" VALUE="http://search.itknowledge.com:80/excite/AT-subscriptionquery.html"><INPUT NAME="bltext" TYPE="hidden" VALUE="Back to Search"><INPUT NAME="sp" TYPE="hidden" VALUE="sp"></FORM></TD></TR></TABLE></CENTER> --><!-- ISBN=1558514341//--><!-- TITLE=The Data Compression Book-//--><!-- AUTHOR=Mark Nelson//--><!-- PUBLISHER=IDG Books Worldwide, Inc.//--><!-- IMPRINT=M & T Books//--><!-- APPENDIX=B//--><!-- PAGES=517-526//--><!-- UNASSIGNED1//--><!-- UNASSIGNED2//--><CENTER><TABLE BORDER><TR><TD><A HREF="ewtoc.html">Table of Contents</A></TD></TR></TABLE></CENTER><P><BR></P><H2><A NAME="Heading1"></A><FONT COLOR="#000077">Appendix B<BR>Test Programs</FONT></H2><P>One of the problems I noticed when testing data compression programs for the Dr. Dobb’s programming contest of 1991 was that of inadequate testing. Many of the programs I was given failed on several of the test files in our compression database.</P><P>After good design, the best weapon to use against these kind of errors is exhaustive testing. I have a test program I use under MS-DOS, named CHURN, which can apply a compression program to every file on a disk volume, performing both compression, decompression, then compare the input to the output. This has proven very helpful to me when testing the software in this book.</P><P>The MS-DOS version of the program is given below. Instructions on how to use this program are found in the program listing.</P><!-- CODE //--><PRE>/**************************START OF CHURN.C****************************** This is a utility program used to test compression/decompression* programs for accuracy, speed, and compression ratios. CHURN is* called with three arguments. The first is a root directory. CHURN* will attempt to compress and then decompress every file in and under* the specified root directory. The next parameter on the command* line is the compression command. CHURN needs to compress the input* file to a file called TEST.CMP. The compression command tells CHURN* how to do this. CHURN will execute the compression command by* passing the command line to DOS using the system() function call.* It attempts to insert the file name into the compression command by* calling sprintf(), with the file name as an argument. This means that* if the compression command has a %s anywhere in it, the name of the* input file should be substituted for it. Finally, the third argument* on the command line should be the command CHURN needs to spawn to* decompress TEST.CMP to TEST.OUT.** An example of how this works using programs created in this book* would look like this:** CHURN C:\ "LZSS-C %%s test.cmp" "LZSS-E test.cmp test.out"** The doubled up % symbols are there to defeat variable substitution* under some command-line interpreters, such as 4DOS.** A more complicated example testing PKZIP might look like this:** CHURN C:\ "TEST %%S" "PKUNZIP TEST.CMP"** where TEST.BAT had two lines that look like this:** COPY %1 TEST.OUT* PKZIP -M TEST.CMP TEST.OUT** CHURN stores a summary of compression in a file called CHURN.LOG. This* file could be used for further analysis by other programs.** To abort this program while it is running, don't start pounding away* on the BREAK or CTRL-C keys. They will just get absorbed by the* compression program. Instead, hit a single key, which will be detected* by CHURN, and used as an abort signal.*/#include <stdio.h>#include <stdlib.h>#include <string.h>#include <time.h>#include <process.h>#include <conio.h>#include <dos.h>/** The findfirst and findnext functions operate nearly identically* under TurboC and MSC. The only difference is that the functions* names, structures, and structure elements all have different names.* I just create macros for these things and redefine them appropriately* here.*/#ifdef__TURBOC__#include <dir.h>#define FILE_INFO struct ffblk#define FIND_FIRST( name, info ) findfirst( ( name ), (info ), FA_DIREC )#define FIND_NEXT( info ) findnext( ( info ) )#define FILE_IS_DIR( info ) ( ( info ).ff_attrib & FA_DIREC )#define FILE_NAME( info ) ( ( info ).ff_name )#else#define MSDOS 1#define FILE_INFO struct find_t#define FIND_FIRST( name, info ) _dos_findfirst( ( name ), _A_SUBDIR, ( info ) )#define FIND_NEXT( info ) _dos_findnext( ( info ) )#define FILE_IS_DIR( info ) ( ( info ).attrib & _A_SUBDIR )#define FILE_NAME( info ) ( ( info ).name )#endif/** Some global variables.*/int total_files:int total_passed;int total_failed;char *compress_command;char *expand_command;FILE *input;FILE *output;FILE *compressed;FILE *log_file;/** Declarations for global routines.*/void churn_files( char *path );int file_is_already_compressed( char *name );void close_all_the_files( void );int compress( char *file_name );void usage_exit( void );/** main() doesn't have to do a whole lot in this program. It* reads in the command line to determine what the root directory* to start looking at is, then it initializes the total byte counts* and the start time. It can then call churn_files(), which does all* the work, then report on the statistics resulting from churn_files.*/void main( int argc, char * argv[] ){ time_t start_time; time_t stop_time; char root_dir[ 81 ]; if ( argc != 4 ) usage_exit(); strcpy( root_dir, argv [ 1 ]; if ( root_dir[ strlen( root_dir ) - 1 ] != `\\' ) strcat( root_dir. "\\" ); compress_command = argv[ 2 ]; expand_command = argv[ 3 ]; setbuf( stdout, NULL ); setbuf( stderr, NULL ); total_files = 0; total_passed = 0; total_failed = 0; log_file = fopen( "CHURN.LOG", "w" ); if ( log_file == NULL ) { printf( "Couldn't open the log file!\n" ); exit( 1 ); } fprintf( log_file, " " "Original Packed\n" ); fprintf( log_file, " File Name " " Size Size Ratio Result\n" ); fprintf( log_file, "_________________ " " _____ _____ ___ ____\n" ); time( &start_time ); churn_files( root_dir ); time( &stop_time ); fprintf( log_file, "\nTotal elapsed time: %f seconds\n", difftime( stop_time, start_time ) ); fprintf( log_file, "Total files: %d\n", total_files ); fprintf( log_file, "Total passed: %d\n", total_passed ); fprintf( log_file, "Total failed: %d\n", total_failed );}/** churn_files() is a routine that sits in a loop looking at* files in the directory specified by its single argument, "path".* As each file is looked at, one of three things happens. If it* is a normal file, and has a compressed extension name, like ".ZIP",* the file is ignored. If it is a normal file, and doesn't have a* compressed extension name, it is compressed and decompressed by* another routine. Finally, if the file is a subdirectory,* churn_files() is called recursively with the file name as its* path argument. This is one of those rare routines where recursion* provides a way to truly simplify the task at hand.*/void churn_files( char *path ){ FILE_INFO file_info; int result; char full_name[ 81 ]; strcpy( full_name, path ); strcat( full_name, "*.*" ); result = FIND_FIRST( full_name, &file_info ); while ( result == 0 ) { if ( kbhit() ) { getch(); exit(0); } if ( FILE_IS_DIR( file_info ) ) { if ( FILE-NAME( file_info )[ 0 ] != '.' ) { strcpy( full_name, path ); strcat( full_name, FILE_NAME( file-info) ); strcat( full_name, "\\" ); churn_files( full_name ); } } else { strcpy( full_name, path ); strcat( full_name, FILE_NAME( file_info ) ); if ( !file_is_already_compressed( full_name ) ) { fprintf( stderr, "Testing %s\n", full_name ); if ( !compress( full_name ) ) fprintf( stderr, "Comparison failed!\n ); } } result = FIND_NEXT( &file_info ); }}/** The job of this routine is simply to check on the file* whose name is passed as an argument. The file extension is compared* against a list of standard extensions that are commonly used on* compressed files. If it matches one of these names, we assume it is* compressed and return a TRUE, otherwise FALSE is returned.** Note that when checking a compression routine for accuracy, it is* probably a good idea to stub out this routine. Trying to compress* "uncompressible" files is a very good exercise for a compression* program. It is probably not a good idea when checking compression* ratios, however.*/int file_is_already_compressed( char *name ){ char *extension; static char *matches[]={ "ZIP", "ICE", "LZH", "ARC", "GIF", "PAK", "ARJ", NULL }; int i; extension=strchr( name, '.' ); if ( extension++ == NULL ) return( 0 ); i = 0; while ( matches[ i ] != NULL ) if ( strcmp( extension, matches[ i++ ] ) == 0 ) return( 1 ); return( 0 );}/** This is the routine that does the majority of the work for* this program. It takes a file whose name is passed here. It first* compresses, then decompresses that file. It then compares the file* to the decompressed output, and reports on the results.*/int compress( char *file_name ){ long new_size; long old_size; int c; char command[ 132 ]; printf( "%s\n", file_name ); fprintf( log_file, "%-40s ", file_name ); sprintf( command, compress_command, file_name ); system( command ); system( command, expand_command, file_name ); system( command ); input = fopen( file_name, "rb" ); output = fopen( "TEST.OUT", "rb" ); compressed = fopen( "TEST.CMP", "rb" ); total_files++; if ( input == NULL || output == NULL || compressed == NULL ) { total_failed++; close_all_the_files(); fprintf( log_file, "Failed, couldn't open file!\n" ); return( 0 ); } fseek( input, OL, SEEK_END ); old_size = ftell( input ); fseek( input, OL, SEEK_SET ); fseek( compressed, OL, SEEK_END ); new_size = ftell( compressed ); fprintf( log_file, "%8ld %8ld ", old_size, new_size ); if ( old_size == 0L ) old_size = 1L; fprintf( log_file, "%41d%% ", 100L - ( ( 100L * new_size ) / old_size ) ); do { c = getc( input ); if ( getc( output ) != c ) { fprintf( log_file, "Failed\n" ); total_failed++; close_all_the_files(); return( 0 ); } } while ( c != EOF ); fprintf( log_file, "Passed\n" ); close_all_the_files(); total_passed++; return( 1 );}void close_all_the_files(){ if ( input != NULL ) fclose( input ); if ( output != NULL ) fclose( output ); if ( compressed != NULL ) fclose( compressed );}/** This routine is used to print out basic instructions for the use* of CHURN, and then exit.*/void usage_exit( void ){ char *usage = "CHURN 1.0. Usage: CHURN root-dir \"compress " "command\" \"expand command\n" "\n" "CHURN is used to test compression programs. " "It does this by compressing\n" "then expanding all of the files in and under " "the specified root dir.\n" "\n" "For each file it finds, CHURN first executes " "the compress command to create a\n" "compressed file called TEST.CMP. It then " "executes the expand command to\n" "create a file called TEST.OUT. CHURN then " "compares the two file to make sure\n" "the compression cycle worked properly.\n" "\n" "The file name to be compressed will be " "inserted into the compress command\n" "using sprintf, with any %%s argument being " "substituted with the name of the\n" "file being compressed. Note that the " "compress and expand commands should be\n" "enclosed in double quotes so that multiple " "words can be included in the\n" "printf( " commands.\n" "\n" "Note that you may have to double the %% " "character on your command line to get\n" "around argument substitution under some " "command processors. Finally, note that\n" "CHURN executes the compression program " "using a system() function call, so\n" "batch files can be used to execute complex\n" "compression sequences.\n" "\n" "Example: CHURN C:\\ \"LZSS-C %%%%s TEST.CMP\" "\"LZSS-C TEST.CMP TEST.OUT\""; puts( usage ); exit( 1 );}</PRE><!-- END CODE //--><P><BR></P><CENTER><TABLE BORDER><TR><TD><A HREF="ewtoc.html">Table of Contents</A></TD></TR></TABLE></CENTER></TD></TR></TABLE></BODY></HTML>⌨️ 快捷键说明
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