1. Re: wrapping my blt...
Noah Smith wrote:
>What is a "wrapper"?
A wrapper is function or procedure interface to an API (application program
interface) that hides the messy implementation details. How's that for a
mouthful?
For example, there are a number of APIs that your code can talk to. There's
BIOS, VESA, the SoundBlaster, Win32, and so on. Functions that are in DLLs
(such as Winsock) can also be considered APIs.
To constrast, a routine that calls VESA to set a pixel could be considered a
wrapper, since it's an interface to the API. On the other hand, a routine
coded from scratch to draw a line is not a wrapper, even if it called VESA
to set the pixel, since it does much more than simply wrap the VESA SetPixel
routine.
>What is a "blit" (we won't mention that I use them, whatever they are)?
Basically, it means to quickly move a chunk of graphics from one location
(memory or screen) to another. From "The Hacker's Dictionary" (online at
blit /blit/ vt. 1. To copy a large array of bits from one part of a
computer's memory to another part, particularly when the memory is being
used to determine what is shown on a display screen. "The storage allocator
picks through the table and copies the good parts up into high memory, and
then blits it all back down again." See bitblt, BLT, dd, cat, blast, snarf.
More generally, to perform some operation (such as toggling) on a large
array of bits while moving them. 2. Sometimes all-capitalized as `BLIT': an
early experimental bit-mapped terminal designed by Rob Pike at Bell Labs,
later commercialized as the AT&T 5620. (The folk etymology from `Bell Labs
Intelligent Terminal' is incorrect. Its creators liked to claim that "Blit"
stood for the Bacon, Lettuce, and Interactive Tomato.)
BLT /B-L-T/, /bl*t/ or (rarely) /belt/ n.,vt. Synonym for blit. This is the
original form of blit and the ancestor of bitblt. It referred to any large
bit-field copy or move operation (one resource-intensive memory-shuffling
operation done on pre-paged versions of ITS, WAITS, and TOPS-10 was
sardonically referred to as `The Big BLT'). The jargon usage has outlasted
the PDP-10 BLock Transfer instruction from which BLT derives; nowadays, the
assembler mnemonic BLT almost always means `Branch if Less Than zero'.
bitblt /bit'blit/ n. [from BLT, q.v.] 1. Any of a family of closely related
algorithms for moving and copying rectangles of bits between main and
display memory on a bit-mapped device, or between two areas of either main
or display memory (the requirement to do the Right Thing in the case of
overlapping source and destination rectangles is what makes BitBlt tricky).
2. Synonym for blit or BLT. Both uses are borderline techspeak.
>> the Win32 Programmer's Reference.hlp from Borland's
>> FTP site.
Take a look at the Euphoria Archives.
-- David Cuny
