diff --git a/splubp.p8 b/splubp.p8
index 26bd681..ace9cd5 100644
--- a/splubp.p8
+++ b/splubp.p8
@@ -89,36 +89,65 @@ end
   if (not self.ffile) self.ffile, self.ptr = self:e()
   for f in all(split(self.ffile, "===", false)) do
    local tok = shatter(f)
-   assert(#tok > 1, "not enough rows in "..tostr(tok)) -- debug
-   assert(#tok[1] == 1 and tok[1][1][1] == ".", "bad extension row: "..tostr(tok[1])) -- debug
-   self.fmts[sub(deli(tok, 1)[1], 1)] = tok
+   if DEBUG then
+    assert(#tok > 1, "not enough rows in "..tostr(tok))
+    assert(#tok[1] == 1, "bad extension row: "..tostr(tok[1]))
+   end
+   self.fmts[deli(tok, 1)[1]] = tok
   end
  end,
 }
 
+function splubp:ppi(n)
+ self.ptr += n
+ return self.ptr - n
+end
+
+function splubp:op()
+ self.cri += 1
+ return self.row[self.cri]
+end
+
+function splubp:c(n)
+ n = n or 1
+ return peek(self:ppi(n), n)
+end
+
+function splubp:i()
+ return %self:ppi(2)
+end
+
+function splubp:n()
+ return $self:ppi(4)
+end
+
 function splubp:e()
- local ret = chr(peek(self.ptr + 2, %self.ptr))
- return ret, self.ptr + 2 + #ret
+ return chr(self:c(self:i()))
 end
 
 -- >8
 -- writer
 
 function splubp:emit_fmts()
- self.ptr = self:emit_e(self.ffile)
+ self:write_e(self.ffile)
+end
+
+-- execute next op (write data)
+function splubp:wnx(...)
+ return self["write_"..self:op()](self, ...)
 end
 
 function splubp:emit_item(obj, filename)
  debug_last_emit = obj -- global debug
  filename = filename or obj._file
  obj._addr = self.ptr
- self.ptr = self:write_s(filename)
+ self:write_s(filename)
  for row in all(self.fmts[split(filename, ".")[2]]) do
   local alt = self.wdirectives[row[1]]
   if alt then
-   self.ptr = alt(self, obj, row)
+   alt(self, obj, row)
   else
-   self.ptr = self:write_fmt(obj[row[1]], row, 2)
+   self:write_fmt(obj[row[1]], row, 2)
   end
  end
 end
@@ -130,22 +159,61 @@ end
 -- TODO: write_fmt: recursive
 --       writing thing
 
+-- Write each argument as one
+-- byte at self.ptr, then
+-- increment self.ptr by the
+-- number of bytes written.
+function splubp:write_c(...)
+ poke(self:ppi(#{...}), ...)
+end
+
+-- Like etch but it takes only
+-- a single 2-byte int.
+function splubp:write_i(i)
+  poke2(self:ppi(2), i)
+end
+
+-- Like etch but it takes only
+-- a single 4-byte number.
+function splubp:write_n(n)
+ poke4(self:ppi(4), n)
+end
+
 function splubp:write_s(s)
- poke(self.ptr, #s, ord(s, 1, #s))
- return self.ptr + 1 + #s
-)
+ self:write_c(#s, ord(s, 1, #s))
 end
 
 function splubp:write_e(s)
- poke2(self.ptr, #s)
- poke(self.ptr+2, ord(s, 1, #s))
- return self.ptr + 2 + #s
+ self:write_i(#s)
+ self:write_c(ord(s,1,#s))
+end
+
+splubp.write_b = splubp.write_c
+
+function splubp:write_shr(n)
+ n <<= self:op()
+ self:wnx(n)
 end
 
 -->8
 -- loader
 
-function splubp:s()
- local ret = chr(peek(self.ptr + 1, @self.ptr))
- return ret, self.ptr + 1 + #ret
+-- execute next op (read)
+function splubp:rnx()
+ return self[self:op()](self)
+end
+
+function splubp:s()
+ return chr(self:c(self:c()))
+end
+
+function splubp:b()
+ local ret = self:c()
+ if (ret < 128) return ret
+ return ret-256
+end
+
+function splubp:shr()
+ local amt = self:op()
+ return self:rnx() >>> amt
 end