diff options
| -rw-r--r-- | Objects/longobject.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/Objects/longobject.c b/Objects/longobject.c index 858be50..1c4a343 100644 --- a/Objects/longobject.c +++ b/Objects/longobject.c @@ -1791,6 +1791,13 @@ remaining, and that's obviously plenty to hold 2*shift+2 digits + 2 bits. Else (bsize is odd and asize < bsize) ah and al each have at most shift digits, so ah+al has at most shift digits + 1 bit, and (ah+al)*(bh+bl) has at most 2*shift+1 digits + 2 bits, and again 2*shift+2 digits is enough to hold it. + +Note that the "lazy" analysis is enough to show that there's always enough +room to subtract al*bl and ah*bh. al and bl each have no more than shift +digits, so al*bl has no more than 2*shift, so there's at least one digit +to spare in the remaining allocated digits. The same is true for ah*bh when +bsize is even. When bsize is odd, ah*bh has at most 2*shift+2 digits, and +there are at least that many remaining allocated digits when bsize is odd. */ /* b has at least twice the digits of a, and a is big enough that Karatsuba |