December 31, 2014Dec 31, 201412/31/14Another round of the semi-annual link clearance.
Do you hear any Christmas music right now? Good. Christmas songs can be played only 1/12 of the year, and people who write algorithms for computer-generated playlists need to identify Christmas songs so that they don’t select them during the other 11/12 of the year.
December 31, 2014Dec 31, 201412/31/14On December 31, 1999, Microsoft Product Support Services were ready in case something horrible happened as the calendar rolled over into the new year.
I’m told that Microsoft Press also had its own Year 2000 plan. They staffed their helpline continuously from Friday evening December 31,
December 30, 2014Dec 30, 201412/30/14Occasionally, somebody will notice that upon installing a program, it managed to pin itself to the taskbar. But just like there is no PinToStartMenu function, there is also no PinToTaskbar function, and for the same reason: Because applications would abuse it and auto-pin themselves because they are so awesome,
December 29, 2014Dec 29, 201412/29/14The signum function is defined as follows:
signum(x) =
−1
if x < 0
signum(x) =
0
if x = 0
signum(x) =
+1
if x > 0
There are a couple of ways of calculating this in SSE integers.
One way is to convert the C idiom
int signum(int x) { return (x >
December 26, 2014Dec 26, 201412/26/14A colleague of mine asked for help puzzling out a mysterious crash
dump which arrived via Windows Error Reporting.
rax=00007fff219c5000 rbx=00000000023c8380 rcx=00000000023c8380
rdx=0000000000000000 rsi=00000000043f0148 rdi=0000000000000000
rip=00007fff21af2d22 rsp=000000000392e518 rbp=000000000392e580
r8=00000000276e4639 r9=00000000043b2360 r10=00000000ffffffff
r11=0000000000000000 r12=0000000000000001 r13=0000000000000000
r14=000000000237cfc0 r15=00000000023d3ea0
iopl=0 nv up ei pl zr na po nc
cs=0033 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246
nosebleed!CNosebleed::OnFrimble+0x1f891a:
00007fff`21af2d22 30488b xor byte ptr [rax-75h],cl ds:00007fff`219c4f8b=41
Well that’s a pretty strange instruction.
December 25, 2014Dec 25, 201412/25/14During the development of Windows, the User Research team tried out an early build of some proposed changes on volunteers from the general community. During one of the tests, they invited the volunteer to just play around with a particular component,
December 24, 2014Dec 24, 201412/24/14If you buy an app from the Windows Store, you can make it available to other users on the same Windows PC. This is useful if you, say, buy an app for your child to use. Here’s how you do it.
December 23, 2014Dec 23, 201412/23/14Look at all that stuff people bought.
December 22, 2014Dec 22, 201412/22/14Today I’m going to set, clear, and test a single bit in an SSE register.
Why?
On Mondays I don’t have to explain why.
First, we use the trick from
last time
that lets us generate constants
where all set bits are contiguous,
December 19, 2014Dec 19, 201412/19/14Commenter Neil presumes that
Windows 286 and later simply fixed up the movable entry table with
jmp selector:offset instructions once and for all.
It could have, but it went one step further.
Recall that the point of the movable entry table is to provide
a fixed location that always refers to a specific function,
