diff --git a/crossfire/codegen.template b/crossfire/codegen.template
index d2926c0..3b36478 100644
--- a/crossfire/codegen.template
+++ b/crossfire/codegen.template
@@ -1,35 +1,56 @@
+@; vim: ft=c
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <stdint.h>
 
-@(define (output-charset num cset)
-  @list{
-    unsigned char @(format "cset~a" num) [] = {
-      @(string-join (map number->string cset) ",")
-    };
-    size_t @(format "cset~a_size" num) = @(length cset);
+@(define c-type "uint64_t")
+@(define c-type-fmt "%lx")
+
+typedef @c-type vartype;
+
+typedef struct {
+  vartype start;
+  vartype end;
+} interval;
+
+typedef struct {
+  size_t length;
+  interval values[];
+} iset;
+
+@(define (output-iset num iset)
+  (define name (format "iset~a" num))
+  (define len (length iset))
+  @list{iset @name = @"{" @len @"," @"{" @(add-between
+      (for/list ([ival (in-list iset)])
+        @list{@"{" @car[ival] @"," @cdr[ival] @"}"})
+      ",") @"}}" ;
 
   })
 
-@(for/list ([i (in-naturals)] [cset (in-vector pattern)])
-  (output-charset i cset))
+@(for/list ([i (in-naturals)] [iset (in-vector pattern)])
+  (output-iset i iset))
 
 int main() {
-    char buf [ @(+ 2 (vector-length pattern)) ];
-    buf [ @(vector-length pattern) ] = '\n';
-    buf [ @(add1 (vector-length pattern)) ] = '\0';
+    char buf [ @(* 20 (vector-length pattern)) ];
     @(for/list ([num (in-naturals)] [cset (in-vector pattern)])
       (define iter (format "i~a" num))
-      (define cset (format "cset~a" num))
-      (define csetsize (format "cset~a_size" num))
+      (define viter (format "v~a" num))
+      (define iset (format "iset~a" num))
       @list{
-        for (size_t @iter = 0; @iter < @csetsize ; @iter ++) @"{"
-          @"buf[" @num @"]" = @cset @"[" @iter @"];"
-          @"\n"
+        for (size_t @iter = 0; @iter < @iset @".length" ; @iter ++) @"{"
+          for (vartype @viter = @iset .values[ @iter ].start; @viter < @iset .values[ @iter ].end; @viter ++) @"{"
+
       })
 
-    fwrite(buf, 1, @(add1 (vector-length pattern)), stdout);
+    @(define vs
+      (string-join (for/list ([i (in-range (vector-length pattern))]) (format "v~a" i)) ","))
+    @(define fmt
+      (string-join (for/list ([i (in-range (vector-length pattern))]) c-type-fmt) " "))
 
-    @(for/list ([cset (in-vector pattern)]) "}")
+    ssize_t res = snprintf(buf, sizeof(buf), @(format "\"~a\\n\"" fmt), @vs );
+    fwrite(buf, res, 1, stdout);
+
+    @(for/list ([cset (in-vector pattern)]) "}}")
 }
-
diff --git a/crossfire/main.rkt b/crossfire/main.rkt
index 0934f28..3fd434c 100644
--- a/crossfire/main.rkt
+++ b/crossfire/main.rkt
@@ -37,23 +37,58 @@
 
 ;; manifest.rkt processing
 
-(define (string->charset str)
-  (for/set ([ch (in-string str)])
-    (char->integer ch)))
+(define (make-iset) '())
 
-(define (range->charset a b)
-  (for/set ([i (in-range a b)]) i))
+(define (iset-add iset start end)
+  (when (> start end)
+    (error "invalid interval" start end))
 
-(define builtin-charsets
-  (hash "?l" (string->charset "abcdefghijklmnopqrstuvwxyz")
-        "?u" (string->charset "ABCDEFGHIJKLMNOPQRSTUVWXYZ")
-        "?d" (string->charset "0123456789")
-        "?s" (string->charset " !\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~")
-        "?a" (range->charset 32 127)
-        "?b" (range->charset 0 256)))
+  (define (iset-merge iset)
+    (define (iset-merge-helper iset acc)
+      (match iset
+        ['() (reverse acc)]
+        [(cons (cons fs fe) r)
+         (match-define (cons (cons afs afe) ar) acc)
+         (if (<= fs afe)
+           (iset-merge-helper r (cons (cons afs (max fe afe)) ar))
+           (iset-merge-helper r (cons (cons fs fe) acc)))]))
+
+    (if (empty? iset)
+      iset
+      (iset-merge-helper (rest iset) (list (first iset)))))
+
+  (define (iset-insert iset start end)
+    (match iset
+      ['() (list (cons start end))]
+      [(cons (cons fs fe) r)
+       (if (>= fs start)
+         (cons (cons start end) iset)
+         (cons (cons fs fe) (iset-insert r start end)))]))
+
+  (iset-merge (iset-insert iset start end)))
+
+(define (char->iset ch)
+  (define cp (char->integer ch))
+  (iset-add (make-iset) cp (add1 cp)))
+
+(define (string->iset str)
+  (for/fold ([iset (make-iset)]) ([ch (in-string str)])
+    (define cp (char->integer ch))
+    (iset-add iset cp (add1 cp))))
+
+(define (range->iset a b)
+  (iset-add (make-iset) a b))
+
+(define builtin-isets
+  (hash "?l" (string->iset "abcdefghijklmnopqrstuvwxyz")
+        "?u" (string->iset "ABCDEFGHIJKLMNOPQRSTUVWXYZ")
+        "?d" (string->iset "0123456789")
+        "?s" (string->iset " !\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~")
+        "?a" (range->iset 32 127)
+        "?b" (range->iset 0 256)))
 
 (define (parse-manifest manifest-def)
-  (struct manifest [name mode command charsets pattern] #:transparent)
+  (struct manifest [name mode command isets pattern] #:transparent)
 
   (define (eq/m x) (curry equal? x))
 
@@ -66,36 +101,40 @@
              (error "manifest attribute missing:" idsym)))]))
 
   (define mf
-    (for/fold ([mf (manifest #f 'stdin #f builtin-charsets #f)])
+    (for/fold ([mf (manifest #f 'stdin #f builtin-isets #f)])
               ([line (in-list manifest-def)])
       (match line
         [(list (? (eq/m 'name)) name) (struct-copy manifest mf [name name])]
         [(list (? (eq/m 'mode)) mode) (struct-copy manifest mf [mode mode])]
         [(list (? (eq/m 'command)) command) (struct-copy manifest mf [command command])]
-        [(list (? (eq/m 'charset)) name val)
+        [(list (? (eq/m 'iset)) name val)
          (struct-copy manifest mf
-                      [charsets (hash-set (manifest-charsets mf)
-                                         (symbol->string name) (string->charset val))])]
+                      [isets (hash-set (manifest-isets mf)
+                                         (symbol->string name) (string->iset val))])]
         [(list (? (eq/m 'pattern)) pattern) (struct-copy manifest mf [pattern pattern])])))
 
   (check-false name)
   (check-false command)
   (check-false pattern)
 
-  (define charsets (manifest-charsets mf))
+  (define isets (manifest-isets mf))
   (define pattern
     (for/vector ([x (in-list (regexp-match* #rx"\\??." (manifest-pattern mf)))])
       (if (= 1 (string-length x))
-        (list (char->integer (string-ref x 0)))
-        (set->list (hash-ref charsets x (lambda () (error "no such charset defined" x)))))))
+        (char->iset (string-ref x 0))
+        (hash-ref isets x (lambda () (error "no such iset defined" x))))))
   (values (manifest-name mf) (manifest-mode mf) (manifest-command mf) pattern))
 
 
 ;; pattern processing
 
+(define (iset-count iset)
+  (for/sum ([ival (in-list iset)])
+    (- (cdr ival) (car ival))))
+
 (define (pattern-count pattern)
   (for/fold ([sum 1]) ([p (in-vector pattern)])
-    (* sum (set-count p))))
+    (* sum (iset-count p))))
 
 ;; design recipe violations follow
 ;; (sorry)
@@ -124,7 +163,8 @@
     '((name "test")
       (mode stdin)
       (command ("meme"))
-      (pattern "test?d?a?a?a"))))
+      (pattern "test?d?a?a?s"))))
 
 ; (pattern-generate pattern (current-output-port))
+; (displayln (pattern-count pattern))
 (pattern-codegen pattern)