1/* $FreeBSD: src/usr.bin/compress/doc/revision.log,v 1.3.2.1 2002/07/16 00:42:48 tjr Exp $ */ 2/* $DragonFly: src/usr.bin/compress/doc/revision.log,v 1.2 2003/06/17 04:29:25 dillon Exp $ */ 3 4/* 5 * $Header: compress.c,v 4.0 85/07/30 12:50:00 joe Release $ 6 * $Log: compress.c,v $ 7 * Revision 4.0 85/07/30 12:50:00 joe 8 * Removed ferror() calls in output routine on every output except first. 9 * Prepared for release to the world. 10 * 11 * Revision 3.6 85/07/04 01:22:21 joe 12 * Remove much wasted storage by overlaying hash table with the tables 13 * used by decompress: tab_suffix[1<<BITS], stack[8000]. Updated USERMEM 14 * computations. Fixed dump_tab() DEBUG routine. 15 * 16 * Revision 3.5 85/06/30 20:47:21 jaw 17 * Change hash function to use exclusive-or. Rip out hash cache. These 18 * speedups render the megamemory version defunct, for now. Make decoder 19 * stack global. Parts of the RCS trunks 2.7, 2.6, and 2.1 no longer apply. 20 * 21 * Revision 3.4 85/06/27 12:00:00 ken 22 * Get rid of all floating-point calculations by doing all compression ratio 23 * calculations in fixed point. 24 * 25 * Revision 3.3 85/06/24 21:53:24 joe 26 * Incorporate portability suggestion for M_XENIX. Got rid of text on #else 27 * and #endif lines. Cleaned up #ifdefs for vax and interdata. 28 * 29 * Revision 3.2 85/06/06 21:53:24 jaw 30 * Incorporate portability suggestions for Z8000, IBM PC/XT from mailing list. 31 * Default to "quiet" output (no compression statistics). 32 * 33 * Revision 3.1 85/05/12 18:56:13 jaw 34 * Integrate decompress() stack speedups (from early pointer mods by McKie). 35 * Repair multi-file USERMEM gaffe. Unify 'force' flags to mimic semantics 36 * of SVR2 'pack'. Streamline block-compress table clear logic. Increase 37 * output byte count by magic number size. 38 * 39 * Revision 3.0 84/11/27 11:50:00 petsd!joe 40 * Set HSIZE depending on BITS. Set BITS depending on USERMEM. Unrolled 41 * loops in clear routines. Added "-C" flag for 2.0 compatibility. Used 42 * unsigned compares on Perkin-Elmer. Fixed foreground check. 43 * 44 * Revision 2.7 84/11/16 19:35:39 ames!jaw 45 * Cache common hash codes based on input statistics; this improves 46 * performance for low-density raster images. Pass on #ifdef bundle 47 * from Turkowski. 48 * 49 * Revision 2.6 84/11/05 19:18:21 ames!jaw 50 * Vary size of hash tables to reduce time for small files. 51 * Tune PDP-11 hash function. 52 * 53 * Revision 2.5 84/10/30 20:15:14 ames!jaw 54 * Junk chaining; replace with the simpler (and, on the VAX, faster) 55 * double hashing, discussed within. Make block compression standard. 56 * 57 * Revision 2.4 84/10/16 11:11:11 ames!jaw 58 * Introduce adaptive reset for block compression, to boost the rate 59 * another several percent. (See mailing list notes.) 60 * 61 * Revision 2.3 84/09/22 22:00:00 petsd!joe 62 * Implemented "-B" block compress. Implemented REVERSE sorting of tab_next. 63 * Bug fix for last bits. Changed fwrite to putchar loop everywhere. 64 * 65 * Revision 2.2 84/09/18 14:12:21 ames!jaw 66 * Fold in news changes, small machine typedef from thomas, 67 * #ifdef interdata from joe. 68 * 69 * Revision 2.1 84/09/10 12:34:56 ames!jaw 70 * Configured fast table lookup for 32-bit machines. 71 * This cuts user time in half for b <= FBITS, and is useful for news batching 72 * from VAX to PDP sites. Also sped up decompress() [fwrite->putc] and 73 * added signal catcher [plus beef in writeerr()] to delete effluvia. 74 * 75 * Revision 2.0 84/08/28 22:00:00 petsd!joe 76 * Add check for foreground before prompting user. Insert maxbits into 77 * compressed file. Force file being uncompressed to end with ".Z". 78 * Added "-c" flag and "zcat". Prepared for release. 79 * 80 * Revision 1.10 84/08/24 18:28:00 turtlevax!ken 81 * Will only compress regular files (no directories), added a magic number 82 * header (plus an undocumented -n flag to handle old files without headers), 83 * added -f flag to force overwriting of possibly existing destination file, 84 * otherwise the user is prompted for a response. Will tack on a .Z to a 85 * filename if it doesn't have one when decompressing. Will only replace 86 * file if it was compressed. 87 * 88 * Revision 1.9 84/08/16 17:28:00 turtlevax!ken 89 * Removed scanargs(), getopt(), added .Z extension and unlimited number of 90 * filenames to compress. Flags may be clustered (-Ddvb12) or separated 91 * (-D -d -v -b 12), or combination thereof. Modes and other status is 92 * copied with copystat(). -O bug for 4.2 seems to have disappeared with 93 * 1.8. 94 * 95 * Revision 1.8 84/08/09 23:15:00 joe 96 * Made it compatible with vax version, installed jim's fixes/enhancements 97 * 98 * Revision 1.6 84/08/01 22:08:00 joe 99 * Sped up algorithm significantly by sorting the compress chain. 100 * 101 * Revision 1.5 84/07/13 13:11:00 srd 102 * Added C version of vax asm routines. Changed structure to arrays to 103 * save much memory. Do unsigned compares where possible (faster on 104 * Perkin-Elmer) 105 * 106 * Revision 1.4 84/07/05 03:11:11 thomas 107 * Clean up the code a little and lint it. (Lint complains about all 108 * the regs used in the asm, but I'm not going to "fix" this.) 109 * 110 * Revision 1.3 84/07/05 02:06:54 thomas 111 * Minor fixes. 112 * 113 * Revision 1.2 84/07/05 00:27:27 thomas 114 * Add variable bit length output. 115 * 116 */ 117 118static char rcs_ident[] = 119 "$Header: compress.c,v 4.0 85/07/30 12:50:00 joe Release $"; 120