Add support for enabling/disabling utf

There are some ocasions where we want to disable the enconding/decoding of utf8, mainly
because it adds an important overhead. This is partial patch for ESC % G and ESC % @,
where they modified the way that st reads and write from/to the serial line, but it does
not modifies how it interacts with the X window part.

diff --git a/st.c b/st.c
index 2594c65..ebbd7ca 100644 (file)
--- a/st.c
+++ b/st.c
@@ -137,6 +137,7 @@ enum term_mode {
        MODE_MOUSEMANY   = 1 << 18,
        MODE_BRCKTPASTE  = 1 << 19,
        MODE_PRINT       = 1 << 20,
+       MODE_UTF8        = 1 << 21,
        MODE_MOUSE       = MODE_MOUSEBTN|MODE_MOUSEMOTION|MODE_MOUSEX10\
                          |MODE_MOUSEMANY,
 };
@@ -158,6 +159,7 @@ enum escape_state {
        ESC_ALTCHARSET = 8,
        ESC_STR_END    = 16, /* a final string was encountered */
        ESC_TEST       = 32, /* Enter in test mode */
+       ESC_UTF8       = 64,
 };
 
 enum window_state {
@@ -412,6 +414,7 @@ static void tfulldirt(void);
 static void techo(Rune);
 static void tcontrolcode(uchar );
 static void tdectest(char );
+static void tdefutf8(char);
 static int32_t tdefcolor(int *, int *, int);
 static void tdeftran(char);
 static inline int match(uint, uint);
@@ -1478,17 +1481,29 @@ ttyread(void)
        if ((ret = read(cmdfd, buf+buflen, LEN(buf)-buflen)) < 0)
                die("Couldn't read from shell: %s\n", strerror(errno));
 
-       /* process every complete utf8 char */
        buflen += ret;
        ptr = buf;
-       while ((charsize = utf8decode(ptr, &unicodep, buflen))) {
-               tputc(unicodep);
-               ptr += charsize;
-               buflen -= charsize;
-       }
 
+       for (;;) {
+               if (IS_SET(MODE_UTF8)) {
+                       /* process a complete utf8 char */
+                       charsize = utf8decode(ptr, &unicodep, buflen);
+                       if (charsize == 0)
+                               break;
+                       tputc(unicodep);
+                       ptr += charsize;
+                       buflen -= charsize;
+
+               } else {
+                       if (buflen <= 0)
+                               break;
+                       tputc(*ptr++ & 0xFF);
+                       buflen--;
+               }
+       }
        /* keep any uncomplete utf8 char for the next call */
-       memmove(buf, ptr, buflen);
+       if (buflen > 0)
+               memmove(buf, ptr, buflen);
 
        return ret;
 }
@@ -1554,15 +1569,26 @@ void
 ttysend(char *s, size_t n)
 {
        int len;
+       char *t, *lim;
        Rune u;
 
        ttywrite(s, n);
-       if (IS_SET(MODE_ECHO))
-               while ((len = utf8decode(s, &u, n)) > 0) {
-                       techo(u);
-                       n -= len;
-                       s += len;
+       if (!IS_SET(MODE_ECHO))
+               return;
+
+       lim = &s[n];
+       for (t = s; t < lim; t += len) {
+               if (IS_SET(MODE_UTF8)) {
+                       len = utf8decode(t, &u, n);
+               } else {
+                       u = *t & 0xFF;
+                       len = 1;
                }
+               if (len <= 0)
+                       break;
+               techo(u);
+               n -= len;
+       }
 }
 
 void
@@ -1656,7 +1682,7 @@ treset(void)
                term.tabs[i] = 1;
        term.top = 0;
        term.bot = term.row - 1;
-       term.mode = MODE_WRAP;
+       term.mode = MODE_WRAP|MODE_UTF8;
        memset(term.trantbl, CS_USA, sizeof(term.trantbl));
        term.charset = 0;
 
@@ -2689,6 +2715,15 @@ techo(Rune u)
        tputc(u);
 }
 
+void
+tdefutf8(char ascii)
+{
+       if (ascii == 'G')
+               term.mode |= MODE_UTF8;
+       else if (ascii == '@')
+               term.mode &= ~MODE_UTF8;
+}
+
 void
 tdeftran(char ascii)
 {
@@ -2851,6 +2886,9 @@ eschandle(uchar ascii)
        case '#':
                term.esc |= ESC_TEST;
                return 0;
+       case '%':
+               term.esc |= ESC_UTF8;
+               return 0;
        case 'P': /* DCS -- Device Control String */
        case '_': /* APC -- Application Program Command */
        case '^': /* PM -- Privacy Message */
@@ -2930,10 +2968,15 @@ tputc(Rune u)
        Glyph *gp;
 
        control = ISCONTROL(u);
-       len = utf8encode(u, c);
-       if (!control && (width = wcwidth(u)) == -1) {
-               memcpy(c, "\357\277\275", 4); /* UTF_INVALID */
-               width = 1;
+       if (!IS_SET(MODE_UTF8)) {
+               c[0] = u;
+               width = len = 1;
+       } else {
+               len = utf8encode(u, c);
+               if (!control && (width = wcwidth(u)) == -1) {
+                       memcpy(c, "\357\277\275", 4); /* UTF_INVALID */
+                       width = 1;
+               }
        }
 
        if (IS_SET(MODE_PRINT))
@@ -2994,6 +3037,8 @@ tputc(Rune u)
                                csihandle();
                        }
                        return;
+               } else if (term.esc & ESC_UTF8) {
+                       tdefutf8(u);
                } else if (term.esc & ESC_ALTCHARSET) {
                        tdeftran(u);
                } else if (term.esc & ESC_TEST) {