Is the TerminateThread function synchronous?
A customer wanted to know whether the TerminateThread function was synchronous. In other words, does the TerminateThread function wait until the target thread has definitely terminated before...
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Dark Pattern: Opt-in above the fold, but opt-out below the fold
One of my colleagues reminded me of a Dark Pattern employed by the installer for the media player for that internet protocol that got the rug pulled out from under it. When you got to the shovelware...
View ArticleServer names: One of the remaining places where IT managers can be a little...
Some time ago, ComputerWorld ran a story on whimsical names for servers. I recall that at my university, one academic department had machines named up and down. I'm sure this led to some strange Who's...
View ArticleCreating an apartment-aware PPL task from nothing
In the Parallel Patterns Library (PPL) of the Concurrency Runtime, there are these things called tasks. Some tasks are apartment-aware, which means that the default continuation context will execute...
View ArticleCreating an awaitable lock for C++ PPL tasks
The C# language (well, more accurately, the BCL) has the ReaderWriterLockSlim class which has a WaitAsync method which returns a task that completes asynchronously when the lock has been acquired....
View ArticleCreating an awaitable lock for WinJS and JavaScript Promises
Last time, we created an awaitable lock for C++ PPL tasks. Let's do the same thing for WinJS Promises (because I needed one of those too). var AwaitableLock = WinJS.Class.define(function...
View ArticleA puzzle aboard the Anacortes-Sidney ferry: How do the cars get off?
For a ferry that goes from one point to another with no stops in between, cars are loaded onto the ferry from one end, and en route, the cars face the direction of travel. When the ferry reaches the...
View ArticleThe PowerPC 600 series, part 1: Introduction
The PowerPC is a RISC processor architecture which grew out of IBM's POWER architecture. Windows NT support was introduced in Windows NT 3.51, and it didn't last long; the last version to support it...
View ArticleThe PowerPC 600 series, part 2: Condition registers and the integer exception...
The integer exception register xer contains a bunch of stuff, but the ones that are relevant to us are Bit Name 0 Summary overflow 1 Overflow 2 Carry Some instructions update the overflow and summary...
View ArticleThe PowerPC 600 series, part 3: Arithmetic
Before we start with arithmetic, we need to have a talk about carry. The PowerPC uses true carry for both addition and subtraction. This is different from the x86 family of processors, for which the...
View ArticleThe PowerPC 600 series, part 4: Bitwise operations and constants
The PowerPC 600 series includes the following bitwise logical operations: and rd, ra, rb ; rd = ra & rb or rd, ra, rb ; rd = ra | rb xor rd, ra, rb ; rd = ra ^ rb nand rd, ra, rb ; rd = ~(ra &...
View ArticleThe PowerPC 600 series, part 5: Rotates and shifts
The Swiss army knife instruction of the PowerPC 600 series instruction set is rlwinm, which stands for "rotate left word immediate and mask." rlwinm rd, ra, imm5a, imm5b, imm5c rlwinm. rd, ra, imm5a,...
View ArticleThe PowerPC 600 series, part 6: Memory access
The PowerPC 600 series has two addressing modes. We will demonstrate them with the lwz instruction, which loads a word from memory. lwz rd, disp16(ra/0) ; load word from memory at ra/0 +...
View ArticleThe PowerPC 600 series, part 7: Atomic memory access and cache coherency
On the PowerPC 600 series, memory accesses to suitably-aligned locations by a single register are atomic,¹ meaning that even in the face of a conflicting operation on another processor, the result...
View ArticleThe PowerPC 600 series, part 8: Control transfer
The PowerPC 600 series has a few types of control transfer instructions. Let's look at direct branches first. b target ; branch to target bl target ; branch to target and link The direct branch...
View ArticleThe PowerPC 600 series, part 9: The table of contents
We saw that the PowerPC 600 series gives you absolute addressing to the top and bottom 32KB of address space. But that doesn't buy you much on Windows NT programs, because all of those addresses are...
View ArticleThe PowerPC 600 series, part 10: Passing parameters, function prologues and...
We saw a little bit of the Windows NT software convention with our introduction to the table of contents. Today we'll start looking at the conventions related to the stack. (Believe it or not, this...
View ArticleThe PowerPC 600 series, part 11: Glue routines
The PowerPC has a concept of a "glue routine". This is a little block of code to assist with control transfer, most of the time to allow a caller in one module to call a function in another module....
View ArticleThe PowerPC 600 series, part 12: leaf functions
On Windows NT for the PowerPC, there is a leaf function optimization available provided your function meets these criteria: It calls no other functions. It does not have an exception handler. It does...
View ArticleThe PowerPC 600 series, part 13: Common patterns
Now that we understand function calls and the table of contents, we can demonstrate some common calling sequences. If you are debugging through PowerPC code, you'll need to be able to recognize these...
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