0.8.13.21:

[sbcl.git] / src / code / bignum.lisp

diff --git a/src/code/bignum.lisp b/src/code/bignum.lisp
index 9fd5085..c188965 100644 (file)
--- a/src/code/bignum.lisp
+++ b/src/code/bignum.lisp
@@ -22,7 +22,7 @@
 ;;;       bignum-logical-and bignum-logical-ior bignum-logical-xor
 ;;;       bignum-logical-not bignum-load-byte bignum-deposit-byte
 ;;;       bignum-truncate bignum-plus-p bignum-compare make-small-bignum
-;;;       bignum-logcount
+;;;       bignum-logbitp bignum-logcount
 ;;;   These symbols define the interface to the compiler:
 ;;;       bignum-type bignum-element-type bignum-index %allocate-bignum
 ;;;       %bignum-length %bignum-set-length %bignum-ref %bignum-set
@@ -519,6 +519,26 @@
 \f
 ;;;; GCD
 
+;;; I'm not sure why I need this FTYPE declaration.  Compiled by the
+;;; target compiler, it can deduce the return type fine, but without
+;;; it, we pay a heavy price in BIGNUM-GCD when compiled by the
+;;; cross-compiler. -- CSR, 2004-07-19
+(declaim (ftype (sfunction (bignum-type bignum-index bignum-type bignum-index)
+                          (unsigned-byte 29))
+               bignum-factors-of-two))
+(defun bignum-factors-of-two (a len-a b len-b)
+  (declare (type bignum-index len-a len-b) (type bignum-type a b))
+  (do ((i 0 (1+ i))
+       (end (min len-a len-b)))
+      ((= i end) (error "Unexpected zero bignums?"))
+    (declare (type bignum-index i end))
+    (let ((or-digits (%logior (%bignum-ref a i) (%bignum-ref b i))))
+      (unless (zerop or-digits)
+       (return (do ((j 0 (1+ j))
+                    (or-digits or-digits (%ashr or-digits 1)))
+                   ((oddp or-digits) (+ (* i digit-size) j))
+                 (declare (type (mod 32) j))))))))
+
 (defun bignum-gcd (a b)
   (declare (type bignum-type a b))
   (let* ((a (if (%bignum-0-or-plusp a (%bignum-length a))
@@ -605,19 +625,6 @@
                     (bignum-buffer-ashift-right a len-a
                                                 (+ (* index digit-size)
                                                    increment)))))))
-
-(defun bignum-factors-of-two (a len-a b len-b)
-  (declare (type bignum-index len-a len-b) (type bignum-type a))
-  (do ((i 0 (1+ i))
-       (end (min len-a len-b)))
-      ((= i end) (error "Unexpected zero bignums?"))
-    (declare (type bignum-index i end))
-    (let ((or-digits (%logior (%bignum-ref a i) (%bignum-ref b i))))
-      (unless (zerop or-digits)
-       (return (do ((j 0 (1+ j))
-                    (or-digits or-digits (%ashr or-digits 1)))
-                   ((oddp or-digits) (+ (* i digit-size) j))
-                 (declare (type (mod 32) j))))))))
 \f
 ;;;; negation
 
@@ -749,13 +756,13 @@
                                       (%normalize-bignum res res-len))
                                      res)))))
          ((> count bignum-len)
-          0)
+          (if (%bignum-0-or-plusp bignum bignum-len) 0 -1))
           ;; Since a FIXNUM should be big enough to address anything in
           ;; memory, including arrays of bits, and since arrays of bits
           ;; take up about the same space as corresponding fixnums, there
           ;; should be no way that we fall through to this case: any shift
           ;; right by a bignum should give zero. But let's check anyway:
-         (t (error "bignum overflow: can't shift right by ~S")))))
+         (t (error "bignum overflow: can't shift right by ~S" count)))))
 
 (defun bignum-ashift-right-digits (bignum digits)
   (declare (type bignum-type bignum)
@@ -812,7 +819,7 @@
          (bignum-ashift-left-unaligned bignum digits n-bits res-len))))
     ;; Left shift by a number too big to be represented as a fixnum
     ;; would exceed our memory capacity, since a fixnum is big enough
-    ;; index any array, including a bit array.
+    ;; to index any array, including a bit array.
     (error "can't represent result of left shift")))
 
 (defun bignum-ashift-left-digits (bignum bignum-len digits)
@@ -980,8 +987,16 @@
               (declare (type bignum-index len))
               (let ((exp (+ exp bias)))
                 (when (> exp max)
-                  (error "Too large to be represented as a ~S:~%  ~S"
-                         format x))
+                  ;; Why a SIMPLE-TYPE-ERROR? Well, this is mainly
+                  ;; called by COERCE, which requires an error of
+                  ;; TYPE-ERROR if the conversion can't happen
+                  ;; (except in certain circumstances when we are
+                  ;; coercing to a FUNCTION) -- CSR, 2002-09-18
+                  (error 'simple-type-error
+                         :format-control "Too large to be represented as a ~S:~%  ~S"
+                         :format-arguments (list format x)
+                         :expected-type format
+                         :datum x))
                 exp)))
 
     (cond
@@ -1001,7 +1016,7 @@
      (t
       (round-up))))))
 \f
-;;;; integer length and logcount
+;;;; integer length and logbitp/logcount
 
 (defun bignum-integer-length (bignum)
   (declare (type bignum-type bignum))
@@ -1013,6 +1028,17 @@
     (+ (integer-length (%fixnum-digit-with-correct-sign digit))
        (* len-1 digit-size))))
 
+(defun bignum-logbitp (index bignum)
+  (declare (type bignum-type bignum))
+  (let ((len (%bignum-length bignum)))
+    (declare (type bignum-index len))
+    (multiple-value-bind (word-index bit-index)
+       (floor index digit-size)
+      (if (>= word-index len)
+         (not (bignum-plus-p bignum))
+         (not (zerop (logand (%bignum-ref bignum word-index)
+                             (ash 1 bit-index))))))))
+
 (defun bignum-logcount (bignum)
   (declare (type bignum-type bignum))
   (let* ((length (%bignum-length bignum))