vi: a few trivial optimizations to keyboard reading code; bump timeout to 50s.

function                                             old     new   delta
edit_file                                            901     912     +11
count_lines                                           74      72      -2
readit                                               306     289     -17
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/2 up/down: 11/-19)             Total: -8 bytes

diff --git a/editors/vi.c b/editors/vi.c
index a757359..7b213df 100644 (file)
--- a/editors/vi.c
+++ b/editors/vi.c
@@ -629,12 +629,12 @@ static void edit_file(char *fn)
                }
 #endif
                do_cmd(c);              // execute the user command
-               //
+
                // poll to see if there is input already waiting. if we are
                // not able to display output fast enough to keep up, skip
                // the display update until we catch up with input.
-               if (mysleep(0) == 0) {
-                       // no input pending- so update output
+               if (!chars_to_parse && mysleep(0) == 0) {
+                       // no input pending - so update output
                        refresh(FALSE);
                        show_status_line();
                }
@@ -2243,8 +2243,10 @@ static char readit(void) // read (maybe cursor) key from stdin
 
        n = chars_to_parse;
        if (n == 0) {
-               // If no data, block waiting for input.
-               n = safe_read(0, readbuffer, 1);
+               // If no data, block waiting for input
+               // (can't read more than minimal ESC sequence -
+               // see "n = 0" below).
+               n = safe_read(0, readbuffer, 3);
                if (n <= 0) {
  error:
                        go_bottom_and_clear_to_eol();
@@ -2264,25 +2266,29 @@ static char readit(void)        // read (maybe cursor) key from stdin
        // If it's an escape sequence, loop through known matches.
        if (c == 27) {
                const struct esc_cmds *eindex;
+               struct pollfd pfd;
 
+               pfd.fd = STDIN_FILENO;
+               pfd.events = POLLIN;
                for (eindex = esccmds; eindex < esccmds + ARRAY_SIZE(esccmds); eindex++) {
-                       // n - position in seq to read
-                       int i = 0; // position in seq to compare
-                       int cnt = strnlen(eindex->seq, 4);
+                       // n - position in sequence we did not read yet
+                       int i = 0; // position in sequence to compare
 
-                       // Loop through chars in this sequence.
+                       // Loop through chars in this sequence
                        for (;;) {
-                               // We've matched this escape sequence up to [i-1]
+                               // So far escape sequence matches up to [i-1]
                                if (n <= i) {
                                        // Need more chars, read another one if it wouldn't block.
                                        // (Note that escape sequences come in as a unit,
                                        // so if we would block it's not really an escape sequence.)
-                                       struct pollfd pfd;
-                                       pfd.fd = 0;
-                                       pfd.events = POLLIN;
-                                       // Timeout is needed to reconnect escape sequences split
-                                       // up by transmission over a serial console.
-                                       if (safe_poll(&pfd, 1, 25)) {
+
+                                       // Timeout is needed to reconnect escape sequences
+                                       // split up by transmission over a serial console.
+                                       // Even though inter-char delay on 1200 baud is <10ms,
+                                       // process scheduling can enlarge it arbitrarily,
+                                       // on both send and receive sides.
+                                       // Erring on the safe side - 5 timer ticks on 100 HZ.
+                                       if (safe_poll(&pfd, 1, 50)) {
                                                if (safe_read(0, readbuffer + n, 1) <= 0)
                                                        goto error;
                                                n++;
@@ -2296,9 +2302,14 @@ static char readit(void) // read (maybe cursor) key from stdin
                                }
                                if (readbuffer[i] != eindex->seq[i])
                                        break; // try next seq
-                               if (++i == cnt) { // entire seq matched
+                               i++;
+                               if (i == 4 || !eindex->seq[i]) { // entire seq matched
                                        c = eindex->val;
                                        n = 0;
+                                       // n -= i; memmove(...);
+                                       // would be more correct,
+                                       // but we never read ahead that much,
+                                       // and n == i here.
                                        goto loop_out;
                                }
                        }
@@ -2306,7 +2317,7 @@ static char readit(void)  // read (maybe cursor) key from stdin
                // We did not find matching sequence, it was a bare ESC.
                // We possibly read and stored more input in readbuffer by now.
        }
-loop_out:
+ loop_out:
 
        chars_to_parse = n;
        return c;