smart clreol algorithm

[unix-history] / usr / src / usr.bin / window / wwupdate.c

diff --git a/usr/src/usr.bin/window/wwupdate.c b/usr/src/usr.bin/window/wwupdate.c
index 06b9741..f2ef793 100644 (file)
--- a/usr/src/usr.bin/window/wwupdate.c
+++ b/usr/src/usr.bin/window/wwupdate.c
@@ -1,5 +1,5 @@
 #ifndef lint
 #ifndef lint

-static char *sccsid = "@(#)wwupdate.c  3.10 83/12/21";
+static char *sccsid = "@(#)wwupdate.c  3.11 84/01/06";

 #endif
 
 #include "ww.h"
 #endif
 
 #include "ww.h"


@@ -9,41 +9,49 @@ wwupdate()
 {
        int i;
        register j;
 {
        int i;
        register j;

-       int c, x;

        register union ww_char *ns, *os;
        register union ww_char *ns, *os;

-       register char *p, *q;
-       char m;

        char *touched;
        char *touched;

-       register didit;
-       char buf[512];                  /* > wwncol */
-       union ww_char lastc;
+       char didit;

 
        wwnupdate++;
        for (i = 0, touched = wwtouched; i < wwnrow; i++, touched++) {
                if (!*touched)
                        continue;
 
        wwnupdate++;
        for (i = 0, touched = wwtouched; i < wwnrow; i++, touched++) {
                if (!*touched)
                        continue;

-               if (*touched & WWU_MAJOR) {
-                       int ncleared = 0;
-                       int nsame = 0;
+               if (*touched & WWU_MAJOR && tt.tt_clreol != 0) {
+                       register gain = 0;
+                       register best_gain = 0;
+                       register best;

 
                        wwnmajline++;
                        j = wwncol;
 
                        wwnmajline++;
                        j = wwncol;

-                       ns = wwns[i];
-                       os = wwos[i];
+                       ns = &wwns[i][j];
+                       os = &wwos[i][j];

                        while (--j >= 0) {
                        while (--j >= 0) {

-                               if (ns->c_w == ' ') {
-                                       if (ns->c_w != os->c_w)
-                                               ncleared++;
-                               } else
-                                       if (ns->c_w == os->c_w)
-                                               nsame++;
-                               ns++;
-                               os++;
+                               /*
+                                * The cost of clearing is:
+                                *      ncol - nblank + X
+                                * The cost of straight update is:
+                                *      ncol - nsame
+                                * We clear if:  nblank - nsame > X
+                                * X is the clreol overhead.
+                                * So we make gain = nblank - nsame.
+                                */
+                               if ((--ns)->c_w == (--os)->c_w)
+                                       gain--;
+                               else
+                                       best_gain--;
+                               if (ns->c_w == ' ')
+                                       gain++;
+                               if (gain >= best_gain) {
+                                       best = j;
+                                       best_gain = gain;
+                               }

                        }
                        }

-                       if (tt.tt_clreol != 0 && ncleared > nsame + 4) {
-                               (*tt.tt_move)(i, 0);
+                       if (best_gain > 4) {
+                               (*tt.tt_move)(i, best);

                                (*tt.tt_clreol)();
                                (*tt.tt_clreol)();

-                               for (j = wwncol, os = wwos[i]; --j >= 0;)
+                               for (j = wwncol - best, os = &wwos[i][best];
+                                    --j >= 0;)

                                        os++->c_w = ' ';
                        } else
                                wwnmajmiss++;
                                        os++->c_w = ' ';
                        } else
                                wwnmajmiss++;


@@ -53,6 +61,13 @@ wwupdate()
                ns = wwns[i];
                os = wwos[i];
                for (j = 0; j < wwncol;) {
                ns = wwns[i];
                os = wwos[i];
                for (j = 0; j < wwncol;) {

+                       register char *p, *q;
+                       char m;
+                       int c;
+                       register n;
+                       char buf[512];                  /* > wwncol */
+                       union ww_char lastc;
+

                        for (; j++ < wwncol && ns++->c_w == os++->c_w;)
                                ;
                        if (j > wwncol)
                        for (; j++ < wwncol && ns++->c_w == os++->c_w;)
                                ;
                        if (j > wwncol)


@@ -62,17 +77,17 @@ wwupdate()
                        c = j - 1;
                        os[-1] = ns[-1];
                        *p++ = ns[-1].c_c;
                        c = j - 1;
                        os[-1] = ns[-1];
                        *p++ = ns[-1].c_c;

-                       x = 5;
+                       n = 5;

                        q = p;
                        while (j < wwncol && (ns->c_m&tt.tt_availmodes) == m) {
                                *p++ = ns->c_c;
                                if (ns->c_w == os->c_w) {
                        q = p;
                        while (j < wwncol && (ns->c_m&tt.tt_availmodes) == m) {
                                *p++ = ns->c_c;
                                if (ns->c_w == os->c_w) {

-                                       if (--x <= 0)
+                                       if (--n <= 0)

                                                break;
                                        os++;
                                        ns++;
                                } else {
                                                break;
                                        os++;
                                        ns++;
                                } else {

-                                       x = 5;
+                                       n = 5;

                                        q = p;
                                        lastc = *os;
                                        *os++ = *ns++;
                                        q = p;
                                        lastc = *os;
                                        *os++ = *ns++;