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diff --git a/src/gnudiff_io.cpp b/src/gnudiff_io.cpp
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+/* File I/O for GNU DIFF.
+
+ Modified for KDiff3 by Joachim Eibl 2003, 2004, 2005.
+ The original file was part of GNU DIFF.
+
+ Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1998, 2001, 2002
+ Free Software Foundation, Inc.
+
+ GNU DIFF is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ GNU DIFF is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; see the file COPYING.
+ If not, write to the Free Software Foundation,
+ 51 Franklin Steet, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+#include "gnudiff_diff.h"
+#include <stdlib.h>
+
+/* Rotate an unsigned value to the left. */
+#define ROL(v, n) ((v) << (n) | (v) >> (sizeof (v) * CHAR_BIT - (n)))
+
+/* Given a hash value and a new character, return a new hash value. */
+#define HASH(h, c) ((c) + ROL (h, 7))
+
+/* The type of a hash value. */
+typedef size_t hash_value;
+verify (hash_value_is_unsigned, ! TYPE_SIGNED (hash_value));
+
+/* Lines are put into equivalence classes of lines that match in lines_differ.
+ Each equivalence class is represented by one of these structures,
+ but only while the classes are being computed.
+ Afterward, each class is represented by a number. */
+struct equivclass
+{
+ lin next; /* Next item in this bucket. */
+ hash_value hash; /* Hash of lines in this class. */
+ const QChar *line; /* A line that fits this class. */
+ size_t length; /* That line's length, not counting its newline. */
+};
+
+/* Hash-table: array of buckets, each being a chain of equivalence classes.
+ buckets[-1] is reserved for incomplete lines. */
+static lin *buckets;
+
+/* Number of buckets in the hash table array, not counting buckets[-1]. */
+static size_t nbuckets;
+
+/* Array in which the equivalence classes are allocated.
+ The bucket-chains go through the elements in this array.
+ The number of an equivalence class is its index in this array. */
+static struct equivclass *equivs;
+
+/* Index of first free element in the array `equivs'. */
+static lin equivs_index;
+
+/* Number of elements allocated in the array `equivs'. */
+static lin equivs_alloc;
+
+
+/* Check for binary files and compare them for exact identity. */
+
+/* Return 1 if BUF contains a non text character.
+ SIZE is the number of characters in BUF. */
+
+#define binary_file_p(buf, size) (memchr (buf, 0, size) != 0)
+
+/* Compare two lines (typically one from each input file)
+ according to the command line options.
+ For efficiency, this is invoked only when the lines do not match exactly
+ but an option like -i might cause us to ignore the difference.
+ Return nonzero if the lines differ. */
+
+bool GnuDiff::lines_differ (const QChar *s1, size_t len1, const QChar *s2, size_t len2 )
+{
+ const QChar *t1 = s1;
+ const QChar *t2 = s2;
+ const QChar *s1end = s1+len1;
+ const QChar *s2end = s2+len2;
+
+ for ( ; ; ++t1, ++t2 )
+ {
+ /* Test for exact char equality first, since it's a common case. */
+ if ( t1!=s1end && t2!=s2end && *t1==*t2 )
+ continue;
+ else
+ {
+ while ( t1!=s1end &&
+ ( bIgnoreWhiteSpace && isWhite( *t1 ) ||
+ bIgnoreNumbers && (t1->isDigit() || *t1=='-' || *t1=='.' )))
+ {
+ ++t1;
+ }
+
+ while ( t2 != s2end &&
+ ( bIgnoreWhiteSpace && isWhite( *t2 ) ||
+ bIgnoreNumbers && (t2->isDigit() || *t2=='-' || *t2=='.' )))
+ {
+ ++t2;
+ }
+
+ if ( t1!=s1end && t2!=s2end )
+ {
+ if (ignore_case)
+ { /* Lowercase comparison. */
+ if ( t1->lower() == t2->lower() )
+ continue;
+ }
+ else if ( *t1 == *t2 )
+ continue;
+ else
+ return true;
+ }
+ else if ( t1==s1end && t2==s2end )
+ return false;
+ else
+ return true;
+ }
+ }
+ return false;
+}
+
+
+/* Split the file into lines, simultaneously computing the equivalence
+ class for each line. */
+
+void GnuDiff::find_and_hash_each_line (struct file_data *current)
+{
+ hash_value h;
+ const QChar *p = current->prefix_end;
+ QChar c;
+ lin i, *bucket;
+ size_t length;
+
+ /* Cache often-used quantities in local variables to help the compiler. */
+ const QChar **linbuf = current->linbuf;
+ lin alloc_lines = current->alloc_lines;
+ lin line = 0;
+ lin linbuf_base = current->linbuf_base;
+ lin *cureqs = (lin*)xmalloc (alloc_lines * sizeof *cureqs);
+ struct equivclass *eqs = equivs;
+ lin eqs_index = equivs_index;
+ lin eqs_alloc = equivs_alloc;
+ const QChar *suffix_begin = current->suffix_begin;
+ const QChar *bufend = current->buffer + current->buffered;
+ bool diff_length_compare_anyway =
+ ignore_white_space != IGNORE_NO_WHITE_SPACE || bIgnoreNumbers;
+ bool same_length_diff_contents_compare_anyway =
+ diff_length_compare_anyway | ignore_case;
+
+ while ( p < suffix_begin)
+ {
+ const QChar *ip = p;
+
+ h = 0;
+
+ /* Hash this line until we find a newline or bufend is reached. */
+ if (ignore_case)
+ switch (ignore_white_space)
+ {
+ case IGNORE_ALL_SPACE:
+ while ( p<bufend && (c = *p) != '\n' )
+ {
+ if (! (isWhite(c) || bIgnoreNumbers && (c.isDigit() || c=='-' || c=='.' ) ))
+ h = HASH (h, c.lower().unicode());
+ ++p;
+ }
+ break;
+
+ default:
+ while ( p<bufend && (c = *p) != '\n' )
+ {
+ h = HASH (h, c.lower().unicode());
+ ++p;
+ }
+ break;
+ }
+ else
+ switch (ignore_white_space)
+ {
+ case IGNORE_ALL_SPACE:
+ while ( p<bufend && (c = *p) != '\n')
+ {
+ if (! (isWhite(c)|| bIgnoreNumbers && (c.isDigit() || c=='-' || c=='.' ) ))
+ h = HASH (h, c.unicode());
+ ++p;
+ }
+ break;
+
+ default:
+ while ( p<bufend && (c = *p) != '\n')
+ {
+ h = HASH (h, c.unicode());
+ ++p;
+ }
+ break;
+ }
+
+ bucket = &buckets[h % nbuckets];
+ length = p - ip;
+ ++p;
+
+ for (i = *bucket; ; i = eqs[i].next)
+ if (!i)
+ {
+ /* Create a new equivalence class in this bucket. */
+ i = eqs_index++;
+ if (i == eqs_alloc)
+ {
+ if ((lin)(PTRDIFF_MAX / (2 * sizeof *eqs)) <= eqs_alloc)
+ xalloc_die ();
+ eqs_alloc *= 2;
+ eqs = (equivclass*)xrealloc (eqs, eqs_alloc * sizeof *eqs);
+ }
+ eqs[i].next = *bucket;
+ eqs[i].hash = h;
+ eqs[i].line = ip;
+ eqs[i].length = length;
+ *bucket = i;
+ break;
+ }
+ else if (eqs[i].hash == h)
+ {
+ const QChar *eqline = eqs[i].line;
+
+ /* Reuse existing class if lines_differ reports the lines
+ equal. */
+ if (eqs[i].length == length)
+ {
+ /* Reuse existing equivalence class if the lines are identical.
+ This detects the common case of exact identity
+ faster than lines_differ would. */
+ if (memcmp (eqline, ip, length*sizeof(QChar)) == 0)
+ break;
+ if (!same_length_diff_contents_compare_anyway)
+ continue;
+ }
+ else if (!diff_length_compare_anyway)
+ continue;
+
+ if (! lines_differ (eqline, eqs[i].length, ip, length))
+ break;
+ }
+
+ /* Maybe increase the size of the line table. */
+ if (line == alloc_lines)
+ {
+ /* Double (alloc_lines - linbuf_base) by adding to alloc_lines. */
+ if ((lin)(PTRDIFF_MAX / 3) <= alloc_lines
+ || (lin)(PTRDIFF_MAX / sizeof *cureqs) <= 2 * alloc_lines - linbuf_base
+ || (lin)(PTRDIFF_MAX / sizeof *linbuf) <= alloc_lines - linbuf_base)
+ xalloc_die ();
+ alloc_lines = 2 * alloc_lines - linbuf_base;
+ cureqs =(lin*) xrealloc (cureqs, alloc_lines * sizeof *cureqs);
+ linbuf += linbuf_base;
+ linbuf = (const QChar**) xrealloc (linbuf,
+ (alloc_lines - linbuf_base) * sizeof *linbuf);
+ linbuf -= linbuf_base;
+ }
+ linbuf[line] = ip;
+ cureqs[line] = i;
+ ++line;
+ }
+
+ current->buffered_lines = line;
+
+ for (i = 0; ; i++)
+ {
+ /* Record the line start for lines in the suffix that we care about.
+ Record one more line start than lines,
+ so that we can compute the length of any buffered line. */
+ if (line == alloc_lines)
+ {
+ /* Double (alloc_lines - linbuf_base) by adding to alloc_lines. */
+ if ((lin)(PTRDIFF_MAX / 3) <= alloc_lines
+ || (lin)(PTRDIFF_MAX / sizeof *cureqs) <= 2 * alloc_lines - linbuf_base
+ || (lin)(PTRDIFF_MAX / sizeof *linbuf) <= alloc_lines - linbuf_base)
+ xalloc_die ();
+ alloc_lines = 2 * alloc_lines - linbuf_base;
+ linbuf += linbuf_base;
+ linbuf = (const QChar**)xrealloc (linbuf,
+ (alloc_lines - linbuf_base) * sizeof *linbuf);
+ linbuf -= linbuf_base;
+ }
+ linbuf[line] = p;
+
+ if ( p >= bufend)
+ break;
+
+ if (context <= i && no_diff_means_no_output)
+ break;
+
+ line++;
+
+ while (p<bufend && *p++ != '\n')
+ continue;
+ }
+
+ /* Done with cache in local variables. */
+ current->linbuf = linbuf;
+ current->valid_lines = line;
+ current->alloc_lines = alloc_lines;
+ current->equivs = cureqs;
+ equivs = eqs;
+ equivs_alloc = eqs_alloc;
+ equivs_index = eqs_index;
+}
+
+/* We have found N lines in a buffer of size S; guess the
+ proportionate number of lines that will be found in a buffer of
+ size T. However, do not guess a number of lines so large that the
+ resulting line table might cause overflow in size calculations. */
+static lin
+guess_lines (lin n, size_t s, size_t t)
+{
+ size_t guessed_bytes_per_line = n < 10 ? 32 : s / (n - 1);
+ lin guessed_lines = MAX (1, t / guessed_bytes_per_line);
+ return MIN (guessed_lines, (lin)(PTRDIFF_MAX / (2 * sizeof (QChar *) + 1) - 5)) + 5;
+}
+
+/* Given a vector of two file_data objects, find the identical
+ prefixes and suffixes of each object. */
+
+void GnuDiff::find_identical_ends (struct file_data filevec[])
+{
+ /* Find identical prefix. */
+ const QChar *p0, *p1, *buffer0, *buffer1;
+ p0 = buffer0 = filevec[0].buffer;
+ p1 = buffer1 = filevec[1].buffer;
+ size_t n0, n1;
+ n0 = filevec[0].buffered;
+ n1 = filevec[1].buffered;
+ const QChar* const pEnd0 = p0 + n0;
+ const QChar* const pEnd1 = p1 + n1;
+
+ if (p0 == p1)
+ /* The buffers are the same; sentinels won't work. */
+ p0 = p1 += n1;
+ else
+ {
+ /* Loop until first mismatch, or end. */
+ while ( p0!=pEnd0 && p1!=pEnd1 && *p0 == *p1 )
+ {
+ p0++;
+ p1++;
+ }
+ }
+
+ /* Now P0 and P1 point at the first nonmatching characters. */
+
+ /* Skip back to last line-beginning in the prefix. */
+ while (p0 != buffer0 && (p0[-1] != '\n' ))
+ p0--, p1--;
+
+ /* Record the prefix. */
+ filevec[0].prefix_end = p0;
+ filevec[1].prefix_end = p1;
+
+ /* Find identical suffix. */
+
+ /* P0 and P1 point beyond the last chars not yet compared. */
+ p0 = buffer0 + n0;
+ p1 = buffer1 + n1;
+
+ const QChar *end0, *beg0;
+ end0 = p0; /* Addr of last char in file 0. */
+
+ /* Get value of P0 at which we should stop scanning backward:
+ this is when either P0 or P1 points just past the last char
+ of the identical prefix. */
+ beg0 = filevec[0].prefix_end + (n0 < n1 ? 0 : n0 - n1);
+
+ /* Scan back until chars don't match or we reach that point. */
+ for (; p0 != beg0; p0--, p1--)
+ {
+ if (*p0 != *p1)
+ {
+ /* Point at the first char of the matching suffix. */
+ beg0 = p0;
+ break;
+ }
+ }
+
+ // Go to the next line (skip last line with a difference)
+ if ( p0 != end0 )
+ {
+ if (*p0 != *p1)
+ ++p0;
+ while ( p0<pEnd0 && *p0++ != '\n')
+ continue;
+ }
+
+ p1 += p0 - beg0;
+
+ /* Record the suffix. */
+ filevec[0].suffix_begin = p0;
+ filevec[1].suffix_begin = p1;
+
+ /* Calculate number of lines of prefix to save.
+
+ prefix_count == 0 means save the whole prefix;
+ we need this for options like -D that output the whole file,
+ or for enormous contexts (to avoid worrying about arithmetic overflow).
+ We also need it for options like -F that output some preceding line;
+ at least we will need to find the last few lines,
+ but since we don't know how many, it's easiest to find them all.
+
+ Otherwise, prefix_count != 0. Save just prefix_count lines at start
+ of the line buffer; they'll be moved to the proper location later.
+ Handle 1 more line than the context says (because we count 1 too many),
+ rounded up to the next power of 2 to speed index computation. */
+
+ const QChar **linbuf0, **linbuf1;
+ lin alloc_lines0, alloc_lines1;
+ lin buffered_prefix, prefix_count, prefix_mask;
+ lin middle_guess, suffix_guess;
+ if (no_diff_means_no_output
+ && context < (lin)(LIN_MAX / 4) && context < (lin)(n0))
+ {
+ middle_guess = guess_lines (0, 0, p0 - filevec[0].prefix_end);
+ suffix_guess = guess_lines (0, 0, buffer0 + n0 - p0);
+ for (prefix_count = 1; prefix_count <= context; prefix_count *= 2)
+ continue;
+ alloc_lines0 = (prefix_count + middle_guess
+ + MIN (context, suffix_guess));
+ }
+ else
+ {
+ prefix_count = 0;
+ alloc_lines0 = guess_lines (0, 0, n0);
+ }
+
+ prefix_mask = prefix_count - 1;
+ lin lines = 0;
+ linbuf0 = (const QChar**) xmalloc (alloc_lines0 * sizeof(*linbuf0));
+ p0 = buffer0;
+
+ /* If the prefix is needed, find the prefix lines. */
+ if (! (no_diff_means_no_output
+ && filevec[0].prefix_end == p0
+ && filevec[1].prefix_end == p1))
+ {
+ end0 = filevec[0].prefix_end;
+ while (p0 != end0)
+ {
+ lin l = lines++ & prefix_mask;
+ if (l == alloc_lines0)
+ {
+ if ((lin)(PTRDIFF_MAX / (2 * sizeof *linbuf0)) <= alloc_lines0)
+ xalloc_die ();
+ alloc_lines0 *= 2;
+ linbuf0 = (const QChar**) xrealloc (linbuf0, alloc_lines0 * sizeof(*linbuf0));
+ }
+ linbuf0[l] = p0;
+ while ( p0<pEnd0 && *p0++ != '\n' )
+ continue;
+ }
+ }
+ buffered_prefix = prefix_count && context < lines ? context : lines;
+
+ /* Allocate line buffer 1. */
+
+ middle_guess = guess_lines (lines, p0 - buffer0, p1 - filevec[1].prefix_end);
+ suffix_guess = guess_lines (lines, p0 - buffer0, buffer1 + n1 - p1);
+ alloc_lines1 = buffered_prefix + middle_guess + MIN (context, suffix_guess);
+ if (alloc_lines1 < buffered_prefix
+ || (lin)(PTRDIFF_MAX / sizeof *linbuf1) <= alloc_lines1)
+ xalloc_die ();
+ linbuf1 = (const QChar**)xmalloc (alloc_lines1 * sizeof(*linbuf1));
+
+ lin i;
+ if (buffered_prefix != lines)
+ {
+ /* Rotate prefix lines to proper location. */
+ for (i = 0; i < buffered_prefix; i++)
+ linbuf1[i] = linbuf0[(lines - context + i) & prefix_mask];
+ for (i = 0; i < buffered_prefix; i++)
+ linbuf0[i] = linbuf1[i];
+ }
+
+ /* Initialize line buffer 1 from line buffer 0. */
+ for (i = 0; i < buffered_prefix; i++)
+ linbuf1[i] = linbuf0[i] - buffer0 + buffer1;
+
+ /* Record the line buffer, adjusted so that
+ linbuf[0] points at the first differing line. */
+ filevec[0].linbuf = linbuf0 + buffered_prefix;
+ filevec[1].linbuf = linbuf1 + buffered_prefix;
+ filevec[0].linbuf_base = filevec[1].linbuf_base = - buffered_prefix;
+ filevec[0].alloc_lines = alloc_lines0 - buffered_prefix;
+ filevec[1].alloc_lines = alloc_lines1 - buffered_prefix;
+ filevec[0].prefix_lines = filevec[1].prefix_lines = lines;
+}
+
+/* If 1 < k, then (2**k - prime_offset[k]) is the largest prime less
+ than 2**k. This table is derived from Chris K. Caldwell's list
+ <http://www.utm.edu/research/primes/lists/2small/>. */
+
+static unsigned char const prime_offset[] =
+{
+ 0, 0, 1, 1, 3, 1, 3, 1, 5, 3, 3, 9, 3, 1, 3, 19, 15, 1, 5, 1, 3, 9, 3,
+ 15, 3, 39, 5, 39, 57, 3, 35, 1, 5, 9, 41, 31, 5, 25, 45, 7, 87, 21,
+ 11, 57, 17, 55, 21, 115, 59, 81, 27, 129, 47, 111, 33, 55, 5, 13, 27,
+ 55, 93, 1, 57, 25
+};
+
+/* Verify that this host's size_t is not too wide for the above table. */
+
+verify (enough_prime_offsets,
+ sizeof (size_t) * CHAR_BIT <= sizeof prime_offset);
+
+/* Given a vector of two file_data objects, read the file associated
+ with each one, and build the table of equivalence classes.
+ Return nonzero if either file appears to be a binary file.
+ If PRETEND_BINARY is nonzero, pretend they are binary regardless. */
+
+bool
+GnuDiff::read_files (struct file_data filevec[], bool /*pretend_binary*/)
+{
+ int i;
+
+ find_identical_ends (filevec);
+
+ equivs_alloc = filevec[0].alloc_lines + filevec[1].alloc_lines + 1;
+ if ((lin)(PTRDIFF_MAX / sizeof *equivs) <= equivs_alloc)
+ xalloc_die ();
+ equivs = (equivclass*)xmalloc (equivs_alloc * sizeof *equivs);
+ /* Equivalence class 0 is permanently safe for lines that were not
+ hashed. Real equivalence classes start at 1. */
+ equivs_index = 1;
+
+ /* Allocate (one plus) a prime number of hash buckets. Use a prime
+ number between 1/3 and 2/3 of the value of equiv_allocs,
+ approximately. */
+ for (i = 9; 1 << i < equivs_alloc / 3; i++)
+ continue;
+ nbuckets = ((size_t) 1 << i) - prime_offset[i];
+ if (PTRDIFF_MAX / sizeof *buckets <= nbuckets)
+ xalloc_die ();
+ buckets = (lin*)zalloc ((nbuckets + 1) * sizeof *buckets);
+ buckets++;
+
+ for (i = 0; i < 2; i++)
+ find_and_hash_each_line (&filevec[i]);
+
+ filevec[0].equiv_max = filevec[1].equiv_max = equivs_index;
+
+ free (equivs);
+ free (buckets - 1);
+
+ return 0;
+}
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