Optimize tputtab.

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

1 files changed, 12 insertions, 16 deletions

diff --git a/st.c b/st.c
index ff9bdd8..c9ef574 100644
--- 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);
 }