inserting: reshuffle some conditions for a teeny bit more speed

Most of the time NO_CONVERT will not be set, the number of lines will
not be zero, and the format of the file will be zero.  Rearrange the
conditions so that they will evaluate as FALSE as soon as possible.

src/files.c

@@ -768,27 +768,25 @@ void read_file(FILE *f, int fd, const char *filename, bool undoable, bool checkw
 	     * the first line if we think it's a *nix file, or on any
 	     * line otherwise), and file conversion isn't disabled,
 	     * handle it! */
-	    if (!ISSET(NO_CONVERT) && (num_lines == 0 || format != 0) &&
+	    if ((num_lines == 0 || format != 0) && !ISSET(NO_CONVERT) &&
 			len > 0 && buf[len - 1] == '\r') {
 		if (format == 0 || format == 2)
 		    format++;
 	    }
 #endif
-
 	    /* Read in the line properly. */
 	    fileptr = read_line(buf, len, fileptr);
-
-	    /* Reset the line length in preparation for the next line. */
-	    len = 0;
-
 	    num_lines++;
+
+	    /* Reset buffer and length in preparation for the next line. */
 	    buf[0] = '\0';
+	    len = 0;
 #ifndef NANO_TINY
 	/* If it's a Mac file ('\r' without '\n' on the first line if we
 	 * think it's a *nix file, or on any line otherwise), and file
 	 * conversion isn't disabled, handle it! */
-	} else if (!ISSET(NO_CONVERT) && (num_lines == 0 ||
-		format != 0) && len > 0 && buf[len - 1] == '\r') {
+	} else if ((num_lines == 0 || format != 0) && !ISSET(NO_CONVERT) &&
+			len > 0 && buf[len - 1] == '\r') {
 	    /* If we currently think the file is a *nix file, set format
 	     * to Mac.  If we currently think the file is a DOS file,
 	     * set format to both DOS and Mac. */
@@ -797,26 +795,21 @@ void read_file(FILE *f, int fd, const char *filename, bool undoable, bool checkw
 
 	    /* Read in the line properly. */
 	    fileptr = read_line(buf, len, fileptr);
-
-	    /* Reset the line length in preparation for the next line.
-	     * Since we've already read in the next character, reset it
-	     * to 1 instead of 0. */
-	    len = 1;
-
 	    num_lines++;
+
+	    /* Store the character after the \r as the first character
+	     * of the next line. */
 	    buf[0] = input;
 	    buf[1] = '\0';
+	    len = 1;
 #endif
 	} else {
-	    /* Calculate the total length of the line.  It might have
-	     * nulls in it, so we can't just use strlen() here. */
+	    /* Keep track of the total length of the line.  It might have
+	     * nulls in it, so we can't just use strlen() later. */
 	    len++;
 
-	    /* Now we allocate a bigger buffer MAX_BUF_SIZE characters
-	     * at a time.  If we allocate a lot of space for one line,
-	     * we may indeed have to use a buffer this big later on, so
-	     * we don't decrease it at all.  We do free it at the end,
-	     * though. */
+	    /* If needed, increase the buffer size, MAX_BUF_SIZE characters at
+	     * a time.  Don't bother decreasing it; it is freed at the end. */
 	    if (len >= bufx) {
 		bufx += MAX_BUF_SIZE;
 		buf = charealloc(buf, bufx);
@@ -843,11 +836,9 @@ void read_file(FILE *f, int fd, const char *filename, bool undoable, bool checkw
 	 * this file is '\r', set format to Mac if we currently think
 	 * the file is a *nix file, or to both DOS and Mac if we
 	 * currently think the file is a DOS file. */
-	if (!ISSET(NO_CONVERT) && buf[len - 1] == '\r' &&
-		(format == 0 || format == 1))
+	if (buf[len - 1] == '\r' && !ISSET(NO_CONVERT) && format < 2)
 	    format += 2;
 #endif
-
 	/* Read in the last line properly. */
 	fileptr = read_line(buf, len, fileptr);
 	num_lines++;