forked from AuroraMiddleware/gtk
490 lines
14 KiB
C
490 lines
14 KiB
C
/*
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* Copyright © 2003 Davide Libenzi
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* 2018 Benjamin Otte
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see <http://www.gnu.org/licenses/>.
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*
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* Authors: Davide Libenzi <davidel@xmailserver.org>
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* Benjamin Otte <otte@gnome.org>
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*/
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#include "config.h"
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#include "gskdiffprivate.h"
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#define XDL_MAX_COST_MIN 256
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#define XDL_HEUR_MIN_COST 256
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#define XDL_LINE_MAX G_MAXSSIZE
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#define XDL_SNAKE_CNT 20
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#define XDL_K_HEUR 4
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#define MAXCOST 20
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struct _GskDiffSettings {
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GCompareDataFunc compare_func;
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GskKeepFunc keep_func;
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GskDeleteFunc delete_func;
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GskInsertFunc insert_func;
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guint allow_abort : 1;
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};
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typedef struct _SplitResult {
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long i1, i2;
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int min_lo, min_hi;
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} SplitResult;
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GskDiffSettings *
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gsk_diff_settings_new (GCompareDataFunc compare_func,
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GskKeepFunc keep_func,
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GskDeleteFunc delete_func,
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GskInsertFunc insert_func)
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{
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GskDiffSettings *settings;
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settings = g_slice_new0 (GskDiffSettings);
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settings->compare_func = compare_func;
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settings->keep_func = keep_func;
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settings->delete_func = delete_func;
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settings->insert_func = insert_func;
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return settings;
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}
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void
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gsk_diff_settings_set_allow_abort (GskDiffSettings *settings,
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gboolean allow_abort)
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{
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settings->allow_abort = allow_abort;
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}
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void
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gsk_diff_settings_free (GskDiffSettings *settings)
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{
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g_slice_free (GskDiffSettings, settings);
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}
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/*
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* See "An O(ND) Difference Algorithm and its Variations", by Eugene Myers.
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* Basically considers a "box" (off1, off2, lim1, lim2) and scan from both
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* the forward diagonal starting from (off1, off2) and the backward diagonal
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* starting from (lim1, lim2). If the K values on the same diagonal crosses
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* returns the furthest point of reach. We might end up having to expensive
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* cases using this algorithm is full, so a little bit of heuristic is needed
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* to cut the search and to return a suboptimal point.
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*/
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static GskDiffResult
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split (gconstpointer *elem1,
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gssize off1,
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gssize lim1,
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gconstpointer *elem2,
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gssize off2,
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gssize lim2,
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gssize *kvdf,
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gssize *kvdb,
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gboolean need_min,
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const GskDiffSettings *settings,
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gpointer data,
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SplitResult *spl)
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{
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gssize dmin = off1 - lim2, dmax = lim1 - off2;
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gssize fmid = off1 - off2, bmid = lim1 - lim2;
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gboolean odd = (fmid - bmid) & 1;
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gssize fmin = fmid, fmax = fmid;
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gssize bmin = bmid, bmax = bmid;
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gssize ec, d, i1, i2, prev1, best, dd, v, k;
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/*
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* Set initial diagonal values for both forward and backward path.
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*/
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kvdf[fmid] = off1;
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kvdb[bmid] = lim1;
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for (ec = 1;; ec++)
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{
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gboolean got_snake = FALSE;
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/*
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* We need to extent the diagonal "domain" by one. If the next
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* values exits the box boundaries we need to change it in the
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* opposite direction because (max - min) must be a power of two.
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* Also we initialize the external K value to -1 so that we can
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* avoid extra conditions check inside the core loop.
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*/
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if (fmin > dmin)
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kvdf[--fmin - 1] = -1;
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else
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++fmin;
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if (fmax < dmax)
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kvdf[++fmax + 1] = -1;
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else
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--fmax;
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for (d = fmax; d >= fmin; d -= 2)
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{
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if (kvdf[d - 1] >= kvdf[d + 1])
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i1 = kvdf[d - 1] + 1;
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else
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i1 = kvdf[d + 1];
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prev1 = i1;
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i2 = i1 - d;
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for (; i1 < lim1 && i2 < lim2; i1++, i2++)
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{
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if (settings->compare_func (elem1[i1], elem2[i2], data) != 0)
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break;
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}
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if (i1 - prev1 > XDL_SNAKE_CNT)
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got_snake = TRUE;
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kvdf[d] = i1;
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if (odd && bmin <= d && d <= bmax && kvdb[d] <= i1)
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{
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spl->i1 = i1;
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spl->i2 = i2;
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spl->min_lo = spl->min_hi = 1;
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return GSK_DIFF_OK;
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}
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}
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/*
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* We need to extent the diagonal "domain" by one. If the next
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* values exits the box boundaries we need to change it in the
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* opposite direction because (max - min) must be a power of two.
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* Also we initialize the external K value to -1 so that we can
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* avoid extra conditions check inside the core loop.
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*/
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if (bmin > dmin)
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kvdb[--bmin - 1] = XDL_LINE_MAX;
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else
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++bmin;
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if (bmax < dmax)
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kvdb[++bmax + 1] = XDL_LINE_MAX;
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else
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--bmax;
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for (d = bmax; d >= bmin; d -= 2)
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{
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if (kvdb[d - 1] < kvdb[d + 1])
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i1 = kvdb[d - 1];
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else
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i1 = kvdb[d + 1] - 1;
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prev1 = i1;
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i2 = i1 - d;
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for (; i1 > off1 && i2 > off2; i1--, i2--)
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{
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if (settings->compare_func (elem1[i1 - 1], elem2[i2 - 1], data) != 0)
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break;
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}
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if (prev1 - i1 > XDL_SNAKE_CNT)
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got_snake = TRUE;
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kvdb[d] = i1;
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if (!odd && fmin <= d && d <= fmax && i1 <= kvdf[d])
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{
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spl->i1 = i1;
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spl->i2 = i2;
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spl->min_lo = spl->min_hi = 1;
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return GSK_DIFF_OK;
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}
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}
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if (need_min)
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continue;
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/*
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* If the edit cost is above the heuristic trigger and if
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* we got a good snake, we sample current diagonals to see
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* if some of them have reached an "interesting" path. Our
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* measure is a function of the distance from the diagonal
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* corner (i1 + i2) penalized with the distance from the
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* mid diagonal itself. If this value is above the current
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* edit cost times a magic factor (XDL_K_HEUR) we consider
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* it interesting.
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*/
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if (got_snake && ec > XDL_HEUR_MIN_COST)
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{
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for (best = 0, d = fmax; d >= fmin; d -= 2)
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{
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dd = d > fmid ? d - fmid: fmid - d;
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i1 = kvdf[d];
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i2 = i1 - d;
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v = (i1 - off1) + (i2 - off2) - dd;
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if (v > XDL_K_HEUR * ec && v > best &&
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off1 + XDL_SNAKE_CNT <= i1 && i1 < lim1 &&
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off2 + XDL_SNAKE_CNT <= i2 && i2 < lim2)
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{
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for (k = 1; ; k++)
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{
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if (settings->compare_func (elem1[i1 - k], elem2[i2 - k], data) != 0)
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break;
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if (k == XDL_SNAKE_CNT)
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{
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best = v;
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spl->i1 = i1;
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spl->i2 = i2;
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break;
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}
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}
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}
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}
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if (best > 0)
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{
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spl->min_lo = 1;
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spl->min_hi = 0;
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return GSK_DIFF_OK;
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}
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for (best = 0, d = bmax; d >= bmin; d -= 2)
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{
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dd = d > bmid ? d - bmid: bmid - d;
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i1 = kvdb[d];
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i2 = i1 - d;
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v = (lim1 - i1) + (lim2 - i2) - dd;
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if (v > XDL_K_HEUR * ec && v > best &&
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off1 < i1 && i1 <= lim1 - XDL_SNAKE_CNT &&
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off2 < i2 && i2 <= lim2 - XDL_SNAKE_CNT)
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{
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for (k = 0; ; k++)
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{
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if (settings->compare_func (elem1[i1 + k], elem2[i2 + k], data) != 0)
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break;
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if (k == XDL_SNAKE_CNT - 1)
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{
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best = v;
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spl->i1 = i1;
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spl->i2 = i2;
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break;
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}
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}
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}
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}
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if (best > 0)
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{
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spl->min_lo = 0;
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spl->min_hi = 1;
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return GSK_DIFF_OK;
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}
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}
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/*
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* Enough is enough. We spent too much time here and now we collect
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* the furthest reaching path using the (i1 + i2) measure.
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*/
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if (ec >= MAXCOST)
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{
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gssize fbest, fbest1, bbest, bbest1;
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if (settings->allow_abort)
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return GSK_DIFF_ABORTED;
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fbest = fbest1 = -1;
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for (d = fmax; d >= fmin; d -= 2)
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{
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i1 = MIN (kvdf[d], lim1);
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i2 = i1 - d;
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if (lim2 < i2)
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i1 = lim2 + d, i2 = lim2;
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if (fbest < i1 + i2)
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{
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fbest = i1 + i2;
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fbest1 = i1;
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}
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}
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bbest = bbest1 = XDL_LINE_MAX;
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for (d = bmax; d >= bmin; d -= 2)
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{
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i1 = MAX (off1, kvdb[d]);
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i2 = i1 - d;
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if (i2 < off2)
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i1 = off2 + d, i2 = off2;
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if (i1 + i2 < bbest)
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{
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bbest = i1 + i2;
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bbest1 = i1;
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}
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}
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if ((lim1 + lim2) - bbest < fbest - (off1 + off2))
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{
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spl->i1 = fbest1;
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spl->i2 = fbest - fbest1;
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spl->min_lo = 1;
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spl->min_hi = 0;
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}
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else
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{
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spl->i1 = bbest1;
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spl->i2 = bbest - bbest1;
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spl->min_lo = 0;
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spl->min_hi = 1;
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}
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return GSK_DIFF_OK;
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}
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}
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}
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/*
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* Rule: "Divide et Impera". Recursively split the box in sub-boxes by calling
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* the box splitting function. Note that the real job (marking changed lines)
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* is done in the two boundary reaching checks.
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*/
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static GskDiffResult
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compare (gconstpointer *elem1,
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gssize off1,
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gssize lim1,
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gconstpointer *elem2,
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gssize off2,
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gssize lim2,
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gssize *kvdf,
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gssize *kvdb,
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gboolean need_min,
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const GskDiffSettings *settings,
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gpointer data)
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{
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/*
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* Shrink the box by walking through each diagonal snake (SW and NE).
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*/
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for (; off1 < lim1 && off2 < lim2; off1++, off2++)
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{
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if (settings->compare_func (elem1[off1], elem2[off2], data) != 0)
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break;
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settings->keep_func (elem1[off1], elem2[off2], data);
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}
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for (; off1 < lim1 && off2 < lim2; lim1--, lim2--)
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{
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if (settings->compare_func (elem1[lim1 - 1], elem2[lim2 - 1], data) != 0)
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break;
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settings->keep_func (elem1[lim1 - 1], elem2[lim2 - 1], data);
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}
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/*
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* If one dimension is empty, then all records on the other one must
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* be obviously changed.
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*/
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if (off1 == lim1)
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{
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for (; off2 < lim2; off2++)
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{
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settings->insert_func (elem2[off2], off2, data);
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}
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}
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else if (off2 == lim2)
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{
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for (; off1 < lim1; off1++)
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{
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settings->delete_func (elem1[off1], off1, data);
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}
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}
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else
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{
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SplitResult spl = { 0, };
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GskDiffResult res;
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/*
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* Divide ...
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*/
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res = split (elem1, off1, lim1,
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elem2, off2, lim2,
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kvdf, kvdb, need_min,
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settings, data,
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&spl);
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if (res != GSK_DIFF_OK)
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return res;
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/*
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* ... et Impera.
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*/
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res = compare (elem1, off1, spl.i1,
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elem2, off2, spl.i2,
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kvdf, kvdb, spl.min_lo,
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settings, data);
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if (res != GSK_DIFF_OK)
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return res;
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res = compare (elem1, spl.i1, lim1,
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elem2, spl.i2, lim2,
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kvdf, kvdb, spl.min_hi,
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settings, data);
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if (res != GSK_DIFF_OK)
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return res;
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}
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return GSK_DIFF_OK;
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}
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#if 0
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ndiags = xe->xdf1.nreff + xe->xdf2.nreff + 3;
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if (!(kvd = (long *) xdl_malloc((2 * ndiags + 2) * sizeof(long)))) {
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xdl_free_env(xe);
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return -1;
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}
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kvdf = kvd;
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kvdb = kvdf + ndiags;
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kvdf += xe->xdf2.nreff + 1;
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kvdb += xe->xdf2.nreff + 1;
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xenv.mxcost = xdl_bogosqrt(ndiags);
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if (xenv.mxcost < XDL_MAX_COST_MIN)
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xenv.mxcost = XDL_MAX_COST_MIN;
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xenv.snake_cnt = XDL_SNAKE_CNT;
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xenv.heur_min = XDL_HEUR_MIN_COST;
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dd1.nrec = xe->xdf1.nreff;
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dd1.ha = xe->xdf1.ha;
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dd1.rchg = xe->xdf1.rchg;
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dd1.rindex = xe->xdf1.rindex;
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dd2.nrec = xe->xdf2.nreff;
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dd2.ha = xe->xdf2.ha;
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dd2.rchg = xe->xdf2.rchg;
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dd2.rindex = xe->xdf2.rindex;
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#endif
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GskDiffResult
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gsk_diff (gconstpointer *elem1,
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gsize n1,
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gconstpointer *elem2,
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gsize n2,
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const GskDiffSettings *settings,
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gpointer data)
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{
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gsize ndiags;
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gssize *kvd, *kvdf, *kvdb;
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GskDiffResult res;
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ndiags = n1 + n2 + 3;
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kvd = g_new (gssize, 2 * ndiags + 2);
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kvdf = kvd;
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kvdb = kvd + ndiags;
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kvdf += n2 + 1;
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kvdb += n2 + 1;
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res = compare (elem1, 0, n1,
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elem2, 0, n2,
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kvdf, kvdb, FALSE,
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settings, data);
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g_free (kvd);
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return res;
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}
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