.

expmod.l

@@ -1,15 +1,59 @@
 #{
    def expmod(b,e,m):
      if e == 0: return 1
-     t = expmod(b,e/2,m)**2 % m
-     if e & 1: t = (t*b) % m
-     return t
+     r = expmod(b,e/2,m)**2 % m
+     if e & 1: r = (r*b) % m
+     return r
 
 B 121666
 E 57896044618658097711785492504343953926634992332820282019728792003956564819947
 M 57896044618658097711785492504343953926634992332820282019728792003956564819949
-t 37095705934669439343138083508754565189542113879843219016388785533085940283556
+
+R 37095705934669439343138083508754565189542113879843219016388785533085940283556
 }#
 
+(de steps (E)
+   (flip
+      (make
+         (while
+            (and
+               (link (swap 'E (/ E 2)))
+               (gt0 E) ) ) ) ) )
+(de expmod-OLD (B E M)
+   (let R 1
+      (for I (steps E)
+         (and
+            (setq R (modulo (* R R) M))
+            (bit? 1 I)
+            (setq R (modulo (* R B) M)) ) )
+      R ) )
+(de expmod-NEW (B E M)
+   (if (=0 E)
+      1
+      (let R (% (** (expmod-NEW B (/ E 2) M) 2) M)
+         (when (bit? 1 E) (setq R (% (* R B) M)))
+         R ) ) )
+
+(println 'expmod-NEW)
+(bench
+   (do 100000
+      (test
+         37095705934669439343138083508754565189542113879843219016388785533085940283556
+         (expmod-NEW
+            121666
+            57896044618658097711785492504343953926634992332820282019728792003956564819947
+            57896044618658097711785492504343953926634992332820282019728792003956564819949 ) ) ) )
+(println 'expmod-OLD)
+(bench
+   (do 100000
+      (test
+         37095705934669439343138083508754565189542113879843219016388785533085940283556
+         (expmod-NEW
+            121666
+            57896044618658097711785492504343953926634992332820282019728792003956564819947
+            57896044618658097711785492504343953926634992332820282019728792003956564819949 ) ) ) )
+
+
+
 (msg 'ok)
 (bye)