/* $NetBSD: zopen.c,v 1.13 2009/04/11 12:24:37 lukem Exp $ */ /*- * Copyright (c) 1985, 1986, 1992, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Diomidis Spinellis and James A. Woods, derived from original * work by Spencer Thomas and Joseph Orost. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #if defined(LIBC_SCCS) && !defined(lint) #if 0 static char sccsid[] = "@(#)zopen.c 8.1 (Berkeley) 6/27/93"; #else static char rcsid[] = "$NetBSD: zopen.c,v 1.13 2009/04/11 12:24:37 lukem Exp $"; #endif #endif /* LIBC_SCCS and not lint */ /*- * fcompress.c - File compression ala IEEE Computer, June 1984. * * Compress authors: * Spencer W. Thomas (decvax!utah-cs!thomas) * Jim McKie (decvax!mcvax!jim) * Steve Davies (decvax!vax135!petsd!peora!srd) * Ken Turkowski (decvax!decwrl!turtlevax!ken) * James A. Woods (decvax!ihnp4!ames!jaw) * Joe Orost (decvax!vax135!petsd!joe) * * Cleaned up and converted to library returning I/O streams by * Diomidis Spinellis . * * zopen(filename, mode, bits) * Returns a FILE * that can be used for read or write. The modes * supported are only "r" and "w". Seeking is not allowed. On * reading the file is decompressed, on writing it is compressed. * The output is compatible with compress(1) with 16 bit tables. * Any file produced by compress(1) can be read. */ #include #include #include #include #include #include #include #include #define BITS 16 /* Default bits. */ #define HSIZE 69001 /* 95% occupancy */ /* A code_int must be able to hold 2**BITS values of type int, and also -1. */ typedef long code_int; typedef long count_int; typedef u_char char_type; static char_type magic_header[] = {'\037', '\235'}; /* 1F 9D */ #define BIT_MASK 0x1f /* Defines for third byte of header. */ #define BLOCK_MASK 0x80 /* * Masks 0x40 and 0x20 are free. I think 0x20 should mean that there is * a fourth header byte (for expansion). */ #define INIT_BITS 9 /* Initial number of bits/code. */ #define MAXCODE(n_bits) ((1 << (n_bits)) - 1) struct s_zstate { FILE *zs_fp; /* File stream for I/O */ char zs_mode; /* r or w */ enum { S_START, S_MIDDLE, S_EOF } zs_state; /* State of computation */ int zs_n_bits; /* Number of bits/code. */ int zs_maxbits; /* User settable max # bits/code. */ code_int zs_maxcode; /* Maximum code, given n_bits. */ code_int zs_maxmaxcode; /* Should NEVER generate this code. */ count_int zs_htab [HSIZE]; u_short zs_codetab [HSIZE]; code_int zs_hsize; /* For dynamic table sizing. */ code_int zs_free_ent; /* First unused entry. */ /* * Block compression parameters -- after all codes are used up, * and compression rate changes, start over. */ int zs_block_compress; int zs_clear_flg; long zs_ratio; count_int zs_checkpoint; int zs_offset; long zs_in_count; /* Length of input. */ long zs_bytes_out; /* Length of compressed output. */ long zs_out_count; /* # of codes output (for debugging). */ char_type zs_buf[BITS]; union { struct { long zs_fcode; code_int zs_ent; code_int zs_hsize_reg; int zs_hshift; } w; /* Write paramenters */ struct { char_type *zs_stackp; int zs_finchar; code_int zs_code, zs_oldcode, zs_incode; int zs_roffset, zs_size; char_type zs_gbuf[BITS]; } r; /* Read parameters */ } u; }; /* Definitions to retain old variable names */ #define fp zs->zs_fp #define zmode zs->zs_mode #define state zs->zs_state #define n_bits zs->zs_n_bits #define maxbits zs->zs_maxbits #define maxcode zs->zs_maxcode #define maxmaxcode zs->zs_maxmaxcode #define htab zs->zs_htab #define codetab zs->zs_codetab #define hsize zs->zs_hsize #define free_ent zs->zs_free_ent #define block_compress zs->zs_block_compress #define clear_flg zs->zs_clear_flg #define ratio zs->zs_ratio #define checkpoint zs->zs_checkpoint #define offset zs->zs_offset #define in_count zs->zs_in_count #define bytes_out zs->zs_bytes_out #define out_count zs->zs_out_count #define buf zs->zs_buf #define fcode zs->u.w.zs_fcode #define hsize_reg zs->u.w.zs_hsize_reg #define ent zs->u.w.zs_ent #define hshift zs->u.w.zs_hshift #define stackp zs->u.r.zs_stackp #define finchar zs->u.r.zs_finchar #define code zs->u.r.zs_code #define oldcode zs->u.r.zs_oldcode #define incode zs->u.r.zs_incode #define roffset zs->u.r.zs_roffset #define size zs->u.r.zs_size #define gbuf zs->u.r.zs_gbuf /* * To save much memory, we overlay the table used by compress() with those * used by decompress(). The tab_prefix table is the same size and type as * the codetab. The tab_suffix table needs 2**BITS characters. We get this * from the beginning of htab. The output stack uses the rest of htab, and * contains characters. There is plenty of room for any possible stack * (stack used to be 8000 characters). */ #define htabof(i) htab[i] #define codetabof(i) codetab[i] #define tab_prefixof(i) codetabof(i) #define tab_suffixof(i) ((char_type *)(htab))[i] #define de_stack ((char_type *)&tab_suffixof(1 << BITS)) #define CHECK_GAP 10000 /* Ratio check interval. */ /* * the next two codes should not be changed lightly, as they must not * lie within the contiguous general code space. */ #define FIRST 257 /* First free entry. */ #define CLEAR 256 /* Table clear output code. */ static int cl_block(struct s_zstate *); static code_int getcode(struct s_zstate *); static int output(struct s_zstate *, code_int); static int zclose(void *); FILE *zopen(const char *, const char *, int); static int zread(void *, char *, int); static int zwrite(void *, const char *, int); /*- * Algorithm from "A Technique for High Performance Data Compression", * Terry A. Welch, IEEE Computer Vol 17, No 6 (June 1984), pp 8-19. * * Algorithm: * Modified Lempel-Ziv method (LZW). Basically finds common * substrings and replaces them with a variable size code. This is * deterministic, and can be done on the fly. Thus, the decompression * procedure needs no input table, but tracks the way the table was built. */ /*- * compress write * * Algorithm: use open addressing double hashing (no chaining) on the * prefix code / next character combination. We do a variant of Knuth's * algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime * secondary probe. Here, the modular division first probe is gives way * to a faster exclusive-or manipulation. Also do block compression with * an adaptive reset, whereby the code table is cleared when the compression * ratio decreases, but after the table fills. The variable-length output * codes are re-sized at this point, and a special CLEAR code is generated * for the decompressor. Late addition: construct the table according to * file size for noticeable speed improvement on small files. Please direct * questions about this implementation to ames!jaw. */ static int zwrite(void *cookie, const char *wbp, int num) { code_int i; int c, disp; struct s_zstate *zs; const u_char *bp; u_char tmp; int count; if (num == 0) return (0); zs = cookie; count = num; bp = (const u_char *)wbp; if (state == S_MIDDLE) goto middle; state = S_MIDDLE; maxmaxcode = 1L << maxbits; if (fwrite(magic_header, sizeof(char), sizeof(magic_header), fp) != sizeof(magic_header)) return (-1); tmp = (u_char)(maxbits | block_compress); if (fwrite(&tmp, sizeof(char), sizeof(tmp), fp) != sizeof(tmp)) return (-1); offset = 0; bytes_out = 3; /* Includes 3-byte header mojo. */ out_count = 0; clear_flg = 0; ratio = 0; in_count = 1; checkpoint = CHECK_GAP; maxcode = MAXCODE(n_bits = INIT_BITS); free_ent = ((block_compress) ? FIRST : 256); ent = *bp++; --count; hshift = 0; for (fcode = (long)hsize; fcode < 65536L; fcode *= 2L) hshift++; hshift = 8 - hshift; /* Set hash code range bound. */ hsize_reg = hsize; memset(htab, 0xff, hsize_reg * sizeof(count_int)); middle: while (count--) { c = *bp++; in_count++; fcode = (long)(((long)c << maxbits) + ent); i = ((c << hshift) ^ ent); /* Xor hashing. */ if (htabof(i) == fcode) { ent = codetabof(i); continue; } else if ((long)htabof(i) < 0) /* Empty slot. */ goto nomatch; disp = hsize_reg - i; /* Secondary hash (after G. Knott). */ if (i == 0) disp = 1; probe: if ((i -= disp) < 0) i += hsize_reg; if (htabof(i) == fcode) { ent = codetabof(i); continue; } if ((long)htabof(i) >= 0) goto probe; nomatch: if (output(zs, (code_int) ent) == -1) return (-1); out_count++; ent = c; if (free_ent < maxmaxcode) { codetabof(i) = free_ent++; /* code -> hashtable */ htabof(i) = fcode; } else if ((count_int)in_count >= checkpoint && block_compress) { if (cl_block(zs) == -1) return (-1); } } return (num); } static int zclose(void *cookie) { struct s_zstate *zs; int rval; zs = cookie; if (zmode == 'w') { /* Put out the final code. */ if (output(zs, (code_int) ent) == -1) { (void)fclose(fp); free(zs); return (-1); } out_count++; if (output(zs, (code_int) - 1) == -1) { (void)fclose(fp); free(zs); return (-1); } } rval = fclose(fp) == EOF ? -1 : 0; free(zs); return (rval); } /*- * Output the given code. * Inputs: * code: A n_bits-bit integer. If == -1, then EOF. This assumes * that n_bits =< (long)wordsize - 1. * Outputs: * Outputs code to the file. * Assumptions: * Chars are 8 bits long. * Algorithm: * Maintain a BITS character long buffer (so that 8 codes will * fit in it exactly). Use the VAX insv instruction to insert each * code in turn. When the buffer fills up empty it and start over. */ static char_type lmask[9] = {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00}; static char_type rmask[9] = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff}; static int output(struct s_zstate *zs, code_int ocode) { int bits, r_off; char_type *bp; r_off = offset; bits = n_bits; bp = buf; if (ocode >= 0) { /* Get to the first byte. */ bp += (r_off >> 3); r_off &= 7; /* * Since ocode is always >= 8 bits, only need to mask the first * hunk on the left. */ *bp = (*bp & rmask[r_off]) | ((ocode << r_off) & lmask[r_off]); bp++; bits -= (8 - r_off); ocode >>= 8 - r_off; /* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */ if (bits >= 8) { *bp++ = ocode; ocode >>= 8; bits -= 8; } /* Last bits. */ if (bits) *bp = ocode; offset += n_bits; if (offset == (n_bits << 3)) { bp = buf; bits = n_bits; bytes_out += bits; if (fwrite(bp, sizeof(char), bits, fp) != (size_t)bits) return (-1); bp += bits; bits = 0; offset = 0; } /* * If the next entry is going to be too big for the ocode size, * then increase it, if possible. */ if (free_ent > maxcode || (clear_flg > 0)) { /* * Write the whole buffer, because the input side won't * discover the size increase until after it has read it. */ if (offset > 0) { if (fwrite(buf, 1, n_bits, fp) != (size_t)n_bits) return (-1); bytes_out += n_bits; } offset = 0; if (clear_flg) { maxcode = MAXCODE(n_bits = INIT_BITS); clear_flg = 0; } else { n_bits++; if (n_bits == maxbits) maxcode = maxmaxcode; else maxcode = MAXCODE(n_bits); } } } else { /* At EOF, write the rest of the buffer. */ if (offset > 0) { offset = (offset + 7) / 8; if (fwrite(buf, 1, offset, fp) != (size_t)offset) return (-1); bytes_out += offset; } offset = 0; } return (0); } /* * Decompress read. This routine adapts to the codes in the file building * the "string" table on-the-fly; requiring no table to be stored in the * compressed file. The tables used herein are shared with those of the * compress() routine. See the definitions above. */ static int zread(void *cookie, char *rbp, int num) { u_int count; struct s_zstate *zs; u_char *bp, header[3]; if (num == 0) return (0); zs = cookie; count = num; bp = (u_char *)rbp; switch (state) { case S_START: state = S_MIDDLE; break; case S_MIDDLE: goto middle; case S_EOF: goto eof; } /* Check the magic number */ if (fread(header, sizeof(char), sizeof(header), fp) != sizeof(header) || memcmp(header, magic_header, sizeof(magic_header)) != 0) { errno = EFTYPE; return (-1); } maxbits = header[2]; /* Set -b from file. */ block_compress = maxbits & BLOCK_MASK; maxbits &= BIT_MASK; maxmaxcode = 1L << maxbits; if (maxbits > BITS) { errno = EFTYPE; return (-1); } /* As above, initialize the first 256 entries in the table. */ maxcode = MAXCODE(n_bits = INIT_BITS); for (code = 255; code >= 0; code--) { tab_prefixof(code) = 0; tab_suffixof(code) = (char_type) code; } free_ent = block_compress ? FIRST : 256; finchar = oldcode = getcode(zs); if (oldcode == -1) /* EOF already? */ return (0); /* Get out of here */ /* First code must be 8 bits = char. */ *bp++ = (u_char)finchar; count--; stackp = de_stack; while ((code = getcode(zs)) > -1) { if ((code == CLEAR) && block_compress) { for (code = 255; code >= 0; code--) tab_prefixof(code) = 0; clear_flg = 1; free_ent = FIRST - 1; if ((code = getcode(zs)) == -1) /* O, untimely death! */ break; } incode = code; /* Special case for KwKwK string. */ if (code >= free_ent) { *stackp++ = finchar; code = oldcode; } /* Generate output characters in reverse order. */ while (code >= 256) { *stackp++ = tab_suffixof(code); code = tab_prefixof(code); } *stackp++ = finchar = tab_suffixof(code); /* And put them out in forward order. */ middle: do { if (count-- == 0) return (num); *bp++ = *--stackp; } while (stackp > de_stack); /* Generate the new entry. */ if ((code = free_ent) < maxmaxcode) { tab_prefixof(code) = (u_short) oldcode; tab_suffixof(code) = finchar; free_ent = code + 1; } /* Remember previous code. */ oldcode = incode; } state = S_EOF; eof: return (num - count); } /*- * Read one code from the standard input. If EOF, return -1. * Inputs: * stdin * Outputs: * code or -1 is returned. */ static code_int getcode(struct s_zstate *zs) { code_int gcode; int r_off, bits; char_type *bp; bp = gbuf; if (clear_flg > 0 || roffset >= size || free_ent > maxcode) { /* * If the next entry will be too big for the current gcode * size, then we must increase the size. This implies reading * a new buffer full, too. */ if (free_ent > maxcode) { n_bits++; if (n_bits == maxbits) /* Won't get any bigger now. */ maxcode = maxmaxcode; else maxcode = MAXCODE(n_bits); } if (clear_flg > 0) { maxcode = MAXCODE(n_bits = INIT_BITS); clear_flg = 0; } size = fread(gbuf, 1, n_bits, fp); if (size <= 0) /* End of file. */ return (-1); roffset = 0; /* Round size down to integral number of codes. */ size = (size << 3) - (n_bits - 1); } r_off = roffset; bits = n_bits; /* Get to the first byte. */ bp += (r_off >> 3); r_off &= 7; /* Get first part (low order bits). */ gcode = (*bp++ >> r_off); bits -= (8 - r_off); r_off = 8 - r_off; /* Now, roffset into gcode word. */ /* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */ if (bits >= 8) { gcode |= *bp++ << r_off; r_off += 8; bits -= 8; } /* High order bits. */ gcode |= (*bp & rmask[bits]) << r_off; roffset += n_bits; return (gcode); } static int cl_block(struct s_zstate *zs) /* Table clear for block compress. */ { long rat; checkpoint = in_count + CHECK_GAP; if (in_count > 0x007fffff) { /* Shift will overflow. */ rat = bytes_out >> 8; if (rat == 0) /* Don't divide by zero. */ rat = 0x7fffffff; else rat = in_count / rat; } else rat = (in_count << 8) / bytes_out; /* 8 fractional bits. */ if (rat > ratio) ratio = rat; else { ratio = 0; memset(htab, 0xff, hsize * sizeof(count_int)); free_ent = FIRST; clear_flg = 1; if (output(zs, (code_int) CLEAR) == -1) return (-1); } return (0); } FILE * zopen(const char *fname, const char *mode, int bits) { struct s_zstate *zs; if ((mode[0] != 'r' && mode[0] != 'w') || mode[1] != '\0' || bits < 0 || bits > BITS) { errno = EINVAL; return (NULL); } if ((zs = calloc(1, sizeof(struct s_zstate))) == NULL) return (NULL); maxbits = bits ? bits : BITS; /* User settable max # bits/code. */ maxmaxcode = 1 << maxbits; /* Should NEVER generate this code. */ hsize = HSIZE; /* For dynamic table sizing. */ free_ent = 0; /* First unused entry. */ block_compress = BLOCK_MASK; clear_flg = 0; ratio = 0; checkpoint = CHECK_GAP; in_count = 1; /* Length of input. */ out_count = 0; /* # of codes output (for debugging). */ state = S_START; roffset = 0; size = 0; /* * Layering compress on top of stdio in order to provide buffering, * and ensure that reads and write work with the data specified. */ if ((fp = fopen(fname, mode)) == NULL) { free(zs); return (NULL); } switch (*mode) { case 'r': zmode = 'r'; return (funopen(zs, zread, NULL, NULL, zclose)); case 'w': zmode = 'w'; return (funopen(zs, NULL, zwrite, NULL, zclose)); } /* NOTREACHED */ return (NULL); }