Clean-up trivially redundant diff.

Also corrects the line numbers in unified output when using
zero lines context.

diff --git a/xdiff/xdiffi.c b/xdiff/xdiffi.c
index 8ea0483..e81bca6 100644 (file)
--- a/xdiff/xdiffi.c
+++ b/xdiff/xdiffi.c
@@ -349,12 +349,7 @@ int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
        kvdf += xe->xdf2.nreff + 1;
        kvdb += xe->xdf2.nreff + 1;
 
-       /*
-        * Classical integer square root approximation using shifts.
-        */
-       xenv.mxcost = 1;
-       for (; ndiags; ndiags >>= 2)
-               xenv.mxcost <<= 1;
+       xenv.mxcost = xdl_bogosqrt(ndiags);
        if (xenv.mxcost < XDL_MAX_COST_MIN)
                xenv.mxcost = XDL_MAX_COST_MIN;
        xenv.snake_cnt = XDL_SNAKE_CNT;

diff --git a/xdiff/xprepare.c b/xdiff/xprepare.c
index 27a0879..add5a75 100644 (file)
--- a/xdiff/xprepare.c
+++ b/xdiff/xprepare.c
@@ -25,6 +25,7 @@
 
 
 #define XDL_KPDIS_RUN 4
+#define XDL_MAX_EQLIMIT 1024
 
 
 
@@ -305,26 +306,48 @@ void xdl_free_env(xdfenv_t *xe) {
 
 
 static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
-       long r, rdis, rpdis;
-
-       for (r = 1, rdis = 0, rpdis = 1; (i - r) >= s; r++) {
+       long r, rdis0, rpdis0, rdis1, rpdis1;
+
+       /*
+        * Scans the lines before 'i' to find a run of lines that either
+        * have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
+        * Note that we always call this function with dis[i] > 1, so the
+        * current line (i) is already a multimatch line.
+        */
+       for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {
                if (!dis[i - r])
-                       rdis++;
+                       rdis0++;
                else if (dis[i - r] == 2)
-                       rpdis++;
+                       rpdis0++;
                else
                        break;
        }
-       for (r = 1; (i + r) <= e; r++) {
+       /*
+        * If the run before the line 'i' found only multimatch lines, we
+        * return 0 and hence we don't make the current line (i) discarded.
+        * We want to discard multimatch lines only when they appear in the
+        * middle of runs with nomatch lines (dis[j] == 0).
+        */
+       if (rdis0 == 0)
+               return 0;
+       for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {
                if (!dis[i + r])
-                       rdis++;
+                       rdis1++;
                else if (dis[i + r] == 2)
-                       rpdis++;
+                       rpdis1++;
                else
                        break;
        }
-
-       return rpdis * XDL_KPDIS_RUN < (rpdis + rdis);
+       /*
+        * If the run after the line 'i' found only multimatch lines, we
+        * return 0 and hence we don't make the current line (i) discarded.
+        */
+       if (rdis1 == 0)
+               return 0;
+       rdis1 += rdis0;
+       rpdis1 += rpdis0;
+
+       return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);
 }
 
 
@@ -334,34 +357,40 @@ static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
  * might be potentially discarded if they happear in a run of discardable.
  */
 static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2) {
-       long i, rhi, nreff;
+       long i, nm, rhi, nreff, mlim;
        unsigned long hav;
        xrecord_t **recs;
        xrecord_t *rec;
        char *dis, *dis1, *dis2;
 
-       if (!(dis = (char *) xdl_malloc((xdf1->nrec + xdf2->nrec + 2) * sizeof(char)))) {
+       if (!(dis = (char *) xdl_malloc(xdf1->nrec + xdf2->nrec + 2))) {
 
                return -1;
        }
-       memset(dis, 0, (xdf1->nrec + xdf2->nrec + 2) * sizeof(char));
+       memset(dis, 0, xdf1->nrec + xdf2->nrec + 2);
        dis1 = dis;
        dis2 = dis1 + xdf1->nrec + 1;
 
+       if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
+               mlim = XDL_MAX_EQLIMIT;
        for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
                hav = (*recs)->ha;
                rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
-               for (rec = xdf2->rhash[rhi]; rec; rec = rec->next)
-                       if (rec->ha == hav && ++dis1[i] == 2)
+               for (nm = 0, rec = xdf2->rhash[rhi]; rec; rec = rec->next)
+                       if (rec->ha == hav && ++nm == mlim)
                                break;
+               dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
        }
 
+       if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
+               mlim = XDL_MAX_EQLIMIT;
        for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
                hav = (*recs)->ha;
                rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
-               for (rec = xdf1->rhash[rhi]; rec; rec = rec->next)
-                       if (rec->ha == hav && ++dis2[i] == 2)
+               for (nm = 0, rec = xdf1->rhash[rhi]; rec; rec = rec->next)
+                       if (rec->ha == hav && ++nm == mlim)
                                break;
+               dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
        }
 
        for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];

diff --git a/xdiff/xutils.c b/xdiff/xutils.c
index afaada1..21ab8e7 100644 (file)
--- a/xdiff/xutils.c
+++ b/xdiff/xutils.c
@@ -29,6 +29,19 @@
 
 
 
+long xdl_bogosqrt(long n) {
+       long i;
+
+       /*
+        * Classical integer square root approximation using shifts.
+        */
+       for (i = 1; n > 0; n >>= 2)
+               i <<= 1;
+
+       return i;
+}
+
+
 int xdl_emit_diffrec(char const *rec, long size, char const *pre, long psize,
                     xdemitcb_t *ecb) {
        mmbuffer_t mb[3];
@@ -244,7 +257,7 @@ int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
        memcpy(buf, "@@ -", 4);
        nb += 4;
 
-       nb += xdl_num_out(buf + nb, c1 ? s1: 0);
+       nb += xdl_num_out(buf + nb, c1 ? s1: s1 - 1);
 
        if (c1 != 1) {
                memcpy(buf + nb, ",", 1);
@@ -256,7 +269,7 @@ int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
        memcpy(buf + nb, " +", 2);
        nb += 2;
 
-       nb += xdl_num_out(buf + nb, c2 ? s2: 0);
+       nb += xdl_num_out(buf + nb, c2 ? s2: s2 - 1);
 
        if (c2 != 1) {
                memcpy(buf + nb, ",", 1);

diff --git a/xdiff/xutils.h b/xdiff/xutils.h
index 55b0d39..ea38ee9 100644 (file)
--- a/xdiff/xutils.h
+++ b/xdiff/xutils.h
@@ -24,6 +24,7 @@
 #define XUTILS_H
 
 
+long xdl_bogosqrt(long n);
 int xdl_emit_diffrec(char const *rec, long size, char const *pre, long psize,
                     xdemitcb_t *ecb);
 int xdl_cha_init(chastore_t *cha, long isize, long icount);