Optimize tputtab.

Before this patch executing
	printf '\e[10000000000I'
or
	printf '\e[10000000000Z'
resulted in long delay.

diff --git a/st.c b/st.c
index ff9bdd8..c9ef574 100644 (file)
--- a/st.c
+++ b/st.c
@@ -375,7 +375,7 @@ static void tmoveto(int, int);
 static void tmoveato(int, int);
 static void tnew(int, int);
 static void tnewline(int);
-static void tputtab(bool);
+static void tputtab(int);
 static void tputc(char *, int);
 static void treset(void);
 static int tresize(int, int);
@@ -1996,8 +1996,7 @@ csihandle(void) {
                break;
        case 'I': /* CHT -- Cursor Forward Tabulation <n> tab stops */
                DEFAULT(csiescseq.arg[0], 1);
-               while(csiescseq.arg[0]--)
-                       tputtab(1);
+               tputtab(csiescseq.arg[0]);
                break;
        case 'J': /* ED -- Clear screen */
                selclear(NULL);
@@ -2065,8 +2064,7 @@ csihandle(void) {
                break;
        case 'Z': /* CBT -- Cursor Backward Tabulation <n> tab stops */
                DEFAULT(csiescseq.arg[0], 1);
-               while(csiescseq.arg[0]--)
-                       tputtab(0);
+               tputtab(-csiescseq.arg[0]);
                break;
        case 'd': /* VPA -- Move to <row> */
                DEFAULT(csiescseq.arg[0], 1);
@@ -2281,19 +2279,17 @@ tdump(void) {
 }
 
 void
-tputtab(bool forward) {
+tputtab(int n) {
        uint x = term.c.x;
 
-       if(forward) {
-               if(x == term.col)
-                       return;
-               for(++x; x < term.col && !term.tabs[x]; ++x)
-                       /* nothing */ ;
-       } else {
-               if(x == 0)
-                       return;
-               for(--x; x > 0 && !term.tabs[x]; --x)
-                       /* nothing */ ;
+       if(n > 0) {
+               while(x < term.col && n--)
+                       for(++x; x < term.col && !term.tabs[x]; ++x)
+                               /* nothing */ ;
+       } else if(n < 0) {
+               while(x > 0 && n++)
+                       for(--x; x > 0 && !term.tabs[x]; --x)
+                               /* nothing */ ;
        }
        tmoveto(x, term.c.y);
 }