- puzzle little closer to machine.
- Posted by unknown@this-world.com on July 3rd, 2005
Can somebody solve the following puzzle ?
Suppose I have a 32 bit machine with 32 bit 32 registers.
How to multiply two integers in such a machine with taking
care of all the overflows. Also MUL or such multiplication
operands are not available in such a machine.
Good Luck!
- Posted by osmium on July 3rd, 2005
<unknown@this-world.com> wrote:
The thing you call a puzzle sounds more like a school assignment. You
wouldn't try to con us, would you?
- Posted by unknown@this-world.com on July 4th, 2005
hah! way back I passed those wonderful school days, and I
luved to solve those school assignments. Its just the job or
sometimes scratching my brain gets me puzzles like this.
Thought by putting this kinddaa puzzles I get to find ways
to do this, but ..... instead of solving u try to find the
origin of the problem ...huh
Thanks to those who give this a shot.. never mind otherwise.
osmium said the following on 07/03/2005 06:18 PM:
- Posted by Jack Klein on July 4th, 2005
On Sun, 03 Jul 2005 12:33:52 GMT, unknown@this-world.com wrote in
comp.programming:
I don't need luck, I know how to do it. In fact, I've written 32 x 32
multiply routines that produced correct 64 bit results on 8 and 16 bit
machines.
The basic binary multiplication algorithm requires only shifts and
adds, and I assume your 32 bit processor provides both of those.
--
Jack Klein
Home: http://JK-Technology.Com
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- Posted by Gerry Quinn on July 4th, 2005
In article <QWQxe.7968$T77.1011@news.cpqcorp.net>, unknown@this-
world.com says...
Just long multiplication, which in binary means just shifts and adds.
In assembler there will normally be a carry flag set after a shift, so
you can tell when you have to add 1 to the 'high' refister before
shifting it.
- Gerry Quinn
- Posted by CBFalconer on July 4th, 2005
Jack Klein wrote:
In addition, the 32*32 -> 64 multiplication can NEVER create an
overflow. Any possible problems arise later, when trying to stuff
a 64 bit entity into a 32 bit pot. If it doesn't fit you must act
on it.
--
"If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
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"Reply" at the bottom of the article headers." - Keith Thompson
- Posted by pete on July 9th, 2005
unknown@this-world.com wrote:
Booth's Algorithm
http://jingwei.eng.hmc.edu/~rwang/e8...ml/node10.html
--
pete
