[writan] add emphasis [format.c] comply with new writan

format.c

@@ -283,6 +283,9 @@ format(FILE *input, FILE *output)
 {
     char c, lastc = '\n';
 
+    char *em_tags[] = {"<em>", "</em>"};
+    int in_em = 0; /* boolean used as index, therefore it's an int */
+
     while ((c = fgetc(input)) != EOF) {
         if (c == '\\') { /* escaped character */
             emit_sanitized_char(fgetc(input), output);
@@ -295,6 +298,10 @@ format(FILE *input, FILE *output)
                 fprintf(output, "<p>");
             emit_link(input, output);
         }
+        else if (c == '_') {
+            fprintf(output, "%s", em_tags[in_em]);
+            in_em = !in_em;
+        }
         else if (c == '`') { /* code block */
             if (fgetc(input) == '`')
                 emit_code_block(lastc, input, output);

resources/writan-example.txt

@@ -32,3 +32,5 @@ You can inline ``code`` blocks.
 
 > Some profound text someone said once. This is a blockquote. It can occupy
 > multiple lines.
+
+One can mark emphasis by surrounding a word with _underscores_.

site-src/lisp.wtn

@@ -2,8 +2,7 @@
 
 > [Lisp] has assisted a number of our most gifted fellow humans in thinking
 > previously impossible thoughts.
-
-**** - Edsger Dijkstra
+_- Edsger Dijkstra_
 
 Lisp is a family of {programming-languages} which uses s-expressions for
 expressing both source code and data. Its syntax is fully parenthesized and