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