improved doc generation

-import io, inspect
+import io, inspect, sys, pathlib, inspect, subprocess, re
 from .cpuinfo import description, parameters, extra, numdescription, regdoc, regname
 from .asm import stdlib, Preprocessor
 
@@ -85,11 +85,84 @@ def _prepro () :
         if not doc :
             continue
         usage, desc = doc.split("\n", 1)
-        out.write(f"## %{usage}\n\n{desc}\n\n")
+        out.write(f"## `%{usage}`\n\n{desc}\n\n")
     return out.getvalue().strip()
 
+def _clean_line (tex) :
+    for old, new in [(r"\textquotesingle{}", '""'),
+                     #(r"\#", "#"),
+                     #(r"\%", "%"),
+                     (r"\ ", " "),
+                     ("{[}", "["),
+                     ("{]}", "]"),
+                     #(r"\$", "$"),
+                     (r"\textless\textless{}", r"\texttt{<<}"),
+                     (r"\textgreater\textgreater{}", r"\texttt{>>}"),
+                     ("\u27a1\ufe0f", r"$\mapsto$"),
+                     ("\u25b6\ufe0f", r"$\rightarrow$"),
+                     (r"\texttt", r"\ttcsrc"),
+                     #("{verbatim}", "{ttcsource}"),
+                     (r"\section", r"\ttcsection"),
+                     (r"\subsection", r"\ttcsubsection"),
+                     ] :
+        tex = tex.replace(old, new)
+    tex = re.sub(r"\\texorpdfstring\{\\ttcsrc\{([^\{\}]*)\}\}\{\1\}", r"\\ttcsrc{\1}", tex)
+    return tex
+
+def _clean_lines (tex) :
+    trim = False
+    for line in tex.splitlines() :
+        if line.startswith(r"\hypertarget") :
+            trim = True
+        elif trim :
+            trim = False
+            yield line.split(r"\label")[0]
+        elif line == r"\tightlist" :
+            pass
+        else :
+            yield line
+
+def clean_tex (tex) :
+    tex = "\n".join(map(_clean_line, _clean_lines(tex)))
+    return tex
+
 if __name__ == "__main__" :
-    print(help.format(regdoc=_regdoc(),
+    import argparse
+    parser = argparse.ArgumentParser(prog="ttc._help", description="TTC help generator")
+    parser.add_argument("-o", dest="output", metavar="PATH",
+                        default=None, type=str,
+                        help="output help to PATH (default: stdout)")
+    parser.add_argument("-f", dest="format", metavar="FMT",
+                        default=None, type=lambda s : str(s).lower(),
+                        help="generate doc as FMT (default: 'md')")
+    args = parser.parse_args()
+    if args.format is None :
+        if args.output in ("-", None) :
+            args.format = "md"
+        else :
+            args.format = pathlib.Path(args.output).suffix.lstrip(".").lower()
+    doc = help.format(regdoc=_regdoc(),
                       instrdoc=_instrdoc(),
                       stdlib=_stdlib(),
-                      prepro=_prepro()).strip())
+                      prepro=_prepro()).strip() +"\n"
+    if args.format == "md" :
+        pass
+    elif args.format == "tex" :
+        doc = subprocess.check_output(["pandoc", "-t", "latex"],
+                                      input=doc, encoding="utf-8")
+        doc = clean_tex(doc)
+    elif args.format == "html" :
+        doc = subprocess.check_output(["pandoc", "-t", "html"],
+                                      input=doc, encoding="utf-8")
+    else :
+        parser.exit(1, inspect.cleandoc("""unsupported format {args.format!r}
+                    use one of
+                     - md: Markdown
+                     - tex: LaTeX
+                     - html: HTML
+                    """) + "\n")
+    if args.output in ("-", None) :
+        out = sys.stdout
+    else :
+        out = open(args.output, "w", encoding="utf-8")
+    out.write(doc)

@@ -162,6 +162,12 @@ html, body {
     margin-top: 5px;
 }
 
+.help h2 code {
+    background-color: #fff;
+    border: 0px;
+    padding: 0px;
+}
+
 .help ul {
     margin: 0px;
     padding-left: 20px;

@@ -146,11 +146,11 @@
 
 # Preprocessor
 
-## %alias NAME REPL
+## `%alias NAME REPL`
 
 define `$NAME` to be replaced by `REPL` for op/macros arguments
 
-## %def NAME ARG...
+## `%def NAME ARG...`
 
 define a macro `NAME`
 ```
@@ -161,7 +161,7 @@ if necessary
 %end
 ```
 
-## %ifalias NAME
+## `%ifalias NAME`
 
 insert text if an alias `NAME` is defined
 ```
@@ -173,7 +173,7 @@ this part is optional
 %endif
 ```
 
-## %ifdef NAME
+## `%ifdef NAME`
 
 insert text if an op/macro `NAME` is defined
 ```
@@ -185,7 +185,7 @@ this part is optional
 %endif
 ```
 
-## %ifnalias NAME
+## `%ifnalias NAME`
 
 insert text if an alias `NAME` is not defined
 ```
@@ -197,7 +197,7 @@ this part is optional
 %endif
 ```
 
-## %ifndef NAME
+## `%ifndef NAME`
 
 insert text if an op/macro `NAME` is not defined
 ```
@@ -209,7 +209,7 @@ this part is optional
 %endif
 ```
 
-## %ifnnum VALUE
+## `%ifnnum VALUE`
 
 insert text if `VALUE` is not a number (or label value)
 ```
@@ -221,7 +221,7 @@ this part is optional
 %endif
 ```
 
-## %ifnreg VALUE
+## `%ifnreg VALUE`
 
 insert text if `VALUE` is not a register
 ```
@@ -233,7 +233,7 @@ this part is optional
 %endif
 ```
 
-## %ifnum VALUE
+## `%ifnum VALUE`
 
 insert text if `VALUE` is a number (or label value)
 ```
@@ -245,7 +245,7 @@ this part is optional
 %endif
 ```
 
-## %ifreg VALUE
+## `%ifreg VALUE`
 
 insert text if `VALUE` is a register
 ```
@@ -257,10 +257,10 @@ this part is optional
 %endif
 ```
 
-## %unalias NAME
+## `%unalias NAME`
 
 undefine previously defined `$NAME`
 
-## %undef NAME
+## `%undef NAME`
 
 undefine a macro `NAME`