Changeset 5584

Timestamp:

Dec 4, 2006, 8:24:26 AM (18 years ago)

Author:

Gary Byers

Message:

BIGNUM-SHIFT-RIGHT-1: handle shift by 0 bits.
BIGNUM-BIGNUM-GCD (whatever it's called): don't bother to shift by 0 bits.

File:

• trunk/ccl/level-0/l0-bignum64.lisp (modified) (4 diffs)

trunk/ccl/level-0/l0-bignum64.lisp

@@ -1850 +1850 @@
              (v-trailing-0-digits (ash v-trailing-0-bits -5)))
         (declare (fixnum u-trailing-0-bits v-trailing-0-bits))
-        (unless (zerop u-trailing-0-digits)
+        (unless (zerop u-trailing-0-bits)
           (bignum-shift-right-loop-1
            (logand u-trailing-0-bits 31)
@@ -1904 +1904 @@
                          u-trailing-0-digits
                          (ash u-trailing-0-bits -5))
-                   (%init-misc 0 u2)
-                   (bignum-shift-right-loop-1
-                    (logand u-trailing-0-bits 31)
-                    u2
-                    u
-                    (the fixnum (1- (the fixnum (- u-len
-                                                   u-trailing-0-digits))))
-                    u-trailing-0-digits)
-                   (rotatef u u2)
-                   (%mostly-normalize-bignum-macro u)
-                   (setq u-len (%bignum-length u)))
+                   (unless (zerop u-trailing-0-bits)
+                     (%init-misc 0 u2)
+                     (bignum-shift-right-loop-1
+                      (logand u-trailing-0-bits 31)
+                      u2
+                      u
+                      (the fixnum (1- (the fixnum (- u-len
+                                                     u-trailing-0-digits))))
+                      u-trailing-0-digits)
+                     (rotatef u u2)
+                     (%mostly-normalize-bignum-macro u)
+                     (setq u-len (%bignum-length u))))
                   (t                    ; (> v u)
                    (bignum-subtract-loop v v-len u u-len v)
@@ -1923 +1924 @@
                          v-trailing-0-digits
                          (ash v-trailing-0-bits -5))
-                   (%init-misc 0 v2)
-                   (bignum-shift-right-loop-1
-                    (logand v-trailing-0-bits 31)
-                    v2
-                    v
-                    (the fixnum (1- (the fixnum (- v-len v-trailing-0-digits))))
-                    v-trailing-0-digits)
-                   (rotatef v v2)
-                   (%mostly-normalize-bignum-macro v)
-                   (setq v-len (%bignum-length v)))))))))))
+                   (unless (zerop v-trailing-0-bits)
+                     (%init-misc 0 v2)
+                     (bignum-shift-right-loop-1
+                      (logand v-trailing-0-bits 31)
+                      v2
+                      v
+                      (the fixnum (1- (the fixnum (- v-len v-trailing-0-digits))))
+                      v-trailing-0-digits)
+                     (rotatef v v2)
+                     (%mostly-normalize-bignum-macro v)
+                     (setq v-len (%bignum-length v))))))))))))
 
 (defun %bignum-bignum-gcd (u v)
@@ -1939 +1941 @@
 
 
-;;; nbits can't be zero here.
 (defun bignum-shift-right-loop-1 (nbits result source len idx)
   (declare (type bignum-type result source)
            (type (mod 32) nbits)
            (type bignum-index idx len))
-  (let* ((rbits (logand 31 (the (mod 32) (- 32 nbits)))))
-    (declare (type (mod 32) rbits))
+  (let* ((rbits (- 32 nbits)))
+    (declare (type (mod 33) rbits))
     (dotimes (j len)
       (let* ((x (bignum-ref source idx)))