1 /* 2 * $Hdr: compress.c,v 4.0 85/07/30 12:50:00 joe Release $ 3 * $Lg: compress.c,v $ 4 * Revision 4.0 85/07/30 12:50:00 joe 5 * Removed ferror() calls in output routine on every output except first. 6 * Prepared for release to the world. 7 * 8 * Revision 3.6 85/07/04 01:22:21 joe 9 * Remove much wasted storage by overlaying hash table with the tables 10 * used by decompress: tab_suffix[1<<BITS], stack[8000]. Updated USERMEM 11 * computations. Fixed dump_tab() DEBUG routine. 12 * 13 * Revision 3.5 85/06/30 20:47:21 jaw 14 * Change hash function to use exclusive-or. Rip out hash cache. These 15 * speedups render the megamemory version defunct, for now. Make decoder 16 * stack global. Parts of the RCS trunks 2.7, 2.6, and 2.1 no longer apply. 17 * 18 * Revision 3.4 85/06/27 12:00:00 ken 19 * Get rid of all floating-point calculations by doing all compression ratio 20 * calculations in fixed point. 21 * 22 * Revision 3.3 85/06/24 21:53:24 joe 23 * Incorporate portability suggestion for M_XENIX. Got rid of text on #else 24 * and #endif lines. Cleaned up #ifdefs for vax and interdata. 25 * 26 * Revision 3.2 85/06/06 21:53:24 jaw 27 * Incorporate portability suggestions for Z8000, IBM PC/XT from mailing list. 28 * Default to "quiet" output (no compression statistics). 29 * 30 * Revision 3.1 85/05/12 18:56:13 jaw 31 * Integrate decompress() stack speedups (from early pointer mods by McKie). 32 * Repair multi-file USERMEM gaffe. Unify 'force' flags to mimic semantics 33 * of SVR2 'pack'. Streamline block-compress table clear logic. Increase 34 * output byte count by magic number size. 35 * 36 * Revision 3.0 84/11/27 11:50:00 petsd!joe 37 * Set HSIZE depending on BITS. Set BITS depending on USERMEM. Unrolled 38 * loops in clear routines. Added "-C" flag for 2.0 compatibility. Used 39 * unsigned compares on Perkin-Elmer. Fixed foreground check. 40 * 41 * Revision 2.7 84/11/16 19:35:39 ames!jaw 42 * Cache common hash codes based on input statistics; this improves 43 * performance for low-density raster images. Pass on #ifdef bundle 44 * from Turkowski. 45 * 46 * Revision 2.6 84/11/05 19:18:21 ames!jaw 47 * Vary size of hash tables to reduce time for small files. 48 * Tune PDP-11 hash function. 49 * 50 * Revision 2.5 84/10/30 20:15:14 ames!jaw 51 * Junk chaining; replace with the simpler (and, on the VAX, faster) 52 * double hashing, discussed within. Make block compression standard. 53 * 54 * Revision 2.4 84/10/16 11:11:11 ames!jaw 55 * Introduce adaptive reset for block compression, to boost the rate 56 * another several percent. (See mailing list notes.) 57 * 58 * Revision 2.3 84/09/22 22:00:00 petsd!joe 59 * Implemented "-B" block compress. Implemented REVERSE sorting of tab_next. 60 * Bug fix for last bits. Changed fwrite to putchar loop everywhere. 61 * 62 * Revision 2.2 84/09/18 14:12:21 ames!jaw 63 * Fold in news changes, small machine typedef from thomas, 64 * #ifdef interdata from joe. 65 * 66 * Revision 2.1 84/09/10 12:34:56 ames!jaw 67 * Configured fast table lookup for 32-bit machines. 68 * This cuts user time in half for b <= FBITS, and is useful for news batching 69 * from VAX to PDP sites. Also sped up decompress() [fwrite->putc] and 70 * added signal catcher [plus beef in writeerr()] to delete effluvia. 71 * 72 * Revision 2.0 84/08/28 22:00:00 petsd!joe 73 * Add check for foreground before prompting user. Insert maxbits into 74 * compressed file. Force file being uncompressed to end with ".Z". 75 * Added "-c" flag and "zcat". Prepared for release. 76 * 77 * Revision 1.10 84/08/24 18:28:00 turtlevax!ken 78 * Will only compress regular files (no directories), added a magic number 79 * header (plus an undocumented -n flag to handle old files without headers), 80 * added -f flag to force overwriting of possibly existing destination file, 81 * otherwise the user is prompted for a response. Will tack on a .Z to a 82 * filename if it doesn't have one when decompressing. Will only replace 83 * file if it was compressed. 84 * 85 * Revision 1.9 84/08/16 17:28:00 turtlevax!ken 86 * Removed scanargs(), getopt(), added .Z extension and unlimited number of 87 * filenames to compress. Flags may be clustered (-Ddvb12) or separated 88 * (-D -d -v -b 12), or combination thereof. Modes and other status is 89 * copied with copystat(). -O bug for 4.2 seems to have disappeared with 90 * 1.8. 91 * 92 * Revision 1.8 84/08/09 23:15:00 joe 93 * Made it compatible with vax version, installed jim's fixes/enhancements 94 * 95 * Revision 1.6 84/08/01 22:08:00 joe 96 * Sped up algorithm significantly by sorting the compress chain. 97 * 98 * Revision 1.5 84/07/13 13:11:00 srd 99 * Added C version of vax asm routines. Changed structure to arrays to 100 * save much memory. Do unsigned compares where possible (faster on 101 * Perkin-Elmer) 102 * 103 * Revision 1.4 84/07/05 03:11:11 thomas 104 * Clean up the code a little and lint it. (Lint complains about all 105 * the regs used in the asm, but I'm not going to "fix" this.) 106 * 107 * Revision 1.3 84/07/05 02:06:54 thomas 108 * Minor fixes. 109 * 110 * Revision 1.2 84/07/05 00:27:27 thomas 111 * Add variable bit length output. 112 * 113 */ 114 115 static char rcs_ident[] = 116 "$Hdr: compress.c,v 4.0 85/07/30 12:50:00 joe Release $"; 117
Indexes created Sat Sep 20 22:09:52 GMT 2025