diff --git a/BUGS b/BUGS
index 26af0e5..f2e372d 100644
--- a/BUGS
+++ b/BUGS
@@ -2,6 +2,8 @@ BUG:
 * (exact->inexact (/ (expt 2 3000) (- (expt 2 3000) 1)))
   should return 1.0, not +nan.0.
 
+* fxsra does not work for large numbers
+
 * pretty-print goes into infinite loop on cyclic data
 * set! on global names is not working.
 * Ensure immutable exports
diff --git a/bin/ikarus b/bin/ikarus
index fb01e5e..b11721d 100755
Binary files a/bin/ikarus and b/bin/ikarus differ
diff --git a/bin/ikarus-numerics.c b/bin/ikarus-numerics.c
index 9a53d94..2bdbf0e 100644
--- a/bin/ikarus-numerics.c
+++ b/bin/ikarus-numerics.c
@@ -1024,6 +1024,18 @@ bits_compliment(unsigned int* src, unsigned int* dst, int n){
   }
 }
 
+static void
+bits_compliment_with_carry(unsigned int* src, unsigned int* dst, int
+    n, int carry){
+  int i;
+  for(i=0; i<n; i++){
+    unsigned int d = src[i];
+    unsigned int c = carry + ~ d;
+    dst[i] = c;
+    carry = (carry && ! d);
+  }
+}
+
 static void
 bits_compliment_logand(unsigned int* s1, unsigned int* s2, unsigned int* dst, int n){
   int carry = 1;
@@ -1036,6 +1048,27 @@ bits_compliment_logand(unsigned int* s1, unsigned int* s2, unsigned int* dst, in
   }
 }
 
+static int
+bits_carry(unsigned int* s, int n){
+  /*
+  int carry = 1;
+  int i;
+  for(i=0; i<n; i++){
+    unsigned int d = s[i];
+    carry = (carry && ! d);
+  }
+  return carry;
+  */
+  int i;
+  for(i=0; i<n; i++){
+    if (s[i] != 0){
+      return 0;
+    }
+  }
+  return 1;
+}
+
+
 
 ikp
 ikrt_bnbnlogand(ikp x, ikp y, ikpcb* pcb){
@@ -1102,6 +1135,104 @@ ikrt_bnbnlogand(ikp x, ikp y, ikpcb* pcb){
   }
 }
 
+
+static void
+copy_bits_shifting_right(unsigned int* src, unsigned int* dst, int n, int m){
+  unsigned int carry = src[0] >> m;
+  int i;
+  for(i=1; i<n; i++){
+    unsigned int b = src[i];
+    dst[i-1] = (b << (32-m)) | carry;
+    carry = b >> m;
+  }
+  dst[n-1] = carry;
+}
+
+
+
+
+ikp
+ikrt_bignum_shift_right(ikp x, ikp y, ikpcb* pcb){
+  int m = unfix(y);
+  ikp fst = ref(x, -vector_tag);
+  int n = ((unsigned int) fst) >> bignum_length_shift;
+  int whole_limb_shift = m >> 5; /* FIXME: 5 are the bits in 32-bit num */
+  int bit_shift = m & 31;
+  int new_limb_count = n - whole_limb_shift;
+  if(bignum_sign_mask & (unsigned int) fst){
+    if(new_limb_count <= 0){
+      return fix(-1);
+    }
+    if(bit_shift == 0){
+      ikp r = ik_alloc(pcb, align(disp_bignum_data + new_limb_count * wordsize));
+      bits_compliment_with_carry(
+          (unsigned int*)(x+off_bignum_data+whole_limb_shift*wordsize),
+          (unsigned int*)(r+disp_bignum_data),
+          new_limb_count,
+          bits_carry((unsigned int*)(x+off_bignum_data), whole_limb_shift));
+      bits_compliment(
+          (unsigned int*)(r+disp_bignum_data),
+          (unsigned int*)(r+disp_bignum_data),
+          new_limb_count);
+      return normalize_bignum(new_limb_count, 1 << bignum_sign_shift, r);
+    } else {
+      ikp r = ik_alloc(pcb, align(disp_bignum_data + new_limb_count * wordsize));
+      bits_compliment_with_carry(
+          (unsigned int*)(x+off_bignum_data+whole_limb_shift*wordsize),
+          (unsigned int*)(r+disp_bignum_data),
+          new_limb_count,
+          bits_carry((unsigned int*)(x+off_bignum_data), whole_limb_shift));
+      copy_bits_shifting_right(
+          (unsigned int*)(r+disp_bignum_data),
+          (unsigned int*)(r+disp_bignum_data),
+          new_limb_count,
+          bit_shift);
+      *((unsigned int*)(r+disp_bignum_data+(new_limb_count-1)*wordsize))
+          |= (-1 << (32 - bit_shift));
+      bits_compliment(
+          (unsigned int*)(r+disp_bignum_data),
+          (unsigned int*)(r+disp_bignum_data),
+          new_limb_count);
+      return normalize_bignum(new_limb_count, 1 << bignum_sign_shift, r);
+      fprintf(stderr, "not yet for negative bignum_shift\n");
+      exit(-1);
+    }
+  } else {
+    if(new_limb_count <= 0){
+      return 0;
+    }
+    if(bit_shift == 0){
+      ikp r = ik_alloc(pcb, align(disp_bignum_data + new_limb_count * wordsize));
+      memcpy(r+disp_bignum_data,
+              x+off_bignum_data+whole_limb_shift*wordsize,
+              new_limb_count * wordsize);
+      return normalize_bignum(new_limb_count, 0, r);
+    } else {
+      ikp r = ik_alloc(pcb, align(disp_bignum_data + new_limb_count * wordsize));
+      copy_bits_shifting_right(
+          (unsigned int*)(x+off_bignum_data+whole_limb_shift*wordsize),
+          (unsigned int*)(r+disp_bignum_data),
+          new_limb_count,
+          bit_shift);
+      return normalize_bignum(new_limb_count, 0, r);
+    }
+  }
+}
+
+
+ikp
+ikrt_fixnum_shift_left(ikp x, ikp y, ikpcb* pcb){
+  fprintf(stderr, "fxshiftleft\n");
+  exit(-1);
+}
+
+ikp
+ikrt_bignum_shift_left(ikp x, ikp y, ikpcb* pcb){
+  fprintf(stderr, "bnshiftleft\n");
+  exit(-1);
+}
+
+
 #if 0
 From TFM:
 void
diff --git a/src/ikarus.boot b/src/ikarus.boot
index 42e844b..54618c4 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/ikarus.numerics.ss b/src/ikarus.numerics.ss
index d684e97..96be0a0 100644
--- a/src/ikarus.numerics.ss
+++ b/src/ikarus.numerics.ss
@@ -312,7 +312,7 @@
           modulo even? odd? logand $two-bignums
           positive? negative? expt gcd lcm numerator denominator exact-integer-sqrt
           quotient+remainder number->string string->number min max
-          abs truncate fltruncate
+          abs truncate fltruncate sra sll
           exact->inexact inexact floor ceiling round log fl=? fl<? fl<=? fl>?
           fl>=? fl+ fl- fl* fl/ flsqrt flmin flzero? flnegative?
           sin cos tan asin acos atan sqrt
@@ -332,7 +332,7 @@
             exact->inexact inexact floor ceiling round log
             exact-integer-sqrt min max abs
             fl=? fl<? fl<=? fl>? fl>=? fl+ fl- fl* fl/ flsqrt flmin
-            flzero? flnegative?
+            flzero? flnegative? sra sll
             sin cos tan asin acos atan sqrt truncate fltruncate
             flround flmax random))
 
@@ -546,8 +546,6 @@
             (if (= r 0)
                 (inexact q)
                 (+ q (f r d)))))))
-    ;(binary/ (exact->inexact ($ratnum-n x)) 
-    ;         (exact->inexact ($ratnum-d x))))
 
   (define binary+
     (lambda (x y)
@@ -2189,6 +2187,43 @@
                 0
                 (error 'random "incorrect argument ~s" n)))
         (error 'random "~s is not a fixnum" n)))
+
+
+  (define (sra n m) 
+    (unless (fixnum? m)
+      (error 'sra "shift amount ~s is not a fixnum"))
+    (cond
+      [(fixnum? n) 
+       (cond
+         [($fx>= m 0) ($fxsra n m)]
+         [else (error 'sra "offset ~s must be non-negative" m)])]
+      [(bignum? n) 
+       (cond
+         [($fx> m 0)  
+          (foreign-call "ikrt_bignum_shift_right" n m)]
+         [($fx= m 0) n]
+         [else (error 'sra "offset ~s must be non-negative" m)])]
+      [else (error 'sra "~s is not an exact integer" n)]))
+
+
+  (define (sll n m) 
+    (unless (fixnum? m)
+      (error 'sll "shift amount ~s is not a fixnum"))
+    (cond
+      [(fixnum? n)
+       (cond
+         [($fx> m 0) 
+          (foreign-call "ikrt_fixnum_shift_left" n m)]
+         [($fx= m 0) n]
+         [else (error 'sll "offset ~s must be non-negative" m)])]
+      [(bignum? n) 
+       (cond
+         [($fx> m 0) 
+          (foreign-call "ikrt_bignum_shift_left" n m)]
+         [($fx= m 0) n]
+         [else (error 'sll "offset ~s must be non-negative" m)])]
+      [else (error 'sll "~s is not an exact integer" n)]))
+
   )
 
 
diff --git a/src/makefile.ss b/src/makefile.ss
index 763b9aa..2db7545 100755
--- a/src/makefile.ss
+++ b/src/makefile.ss
@@ -450,6 +450,8 @@
     [fxmodulo                i]
     [fxsll                   i]
     [fxsra                   i]
+    [sra                     i]
+    [sll                     i]
     [fxlogand                i]
     [logand                  i]
     [fxlogxor                i]