FAST Forth Native-Language Embedded Computers

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0 \ Lahe1 Raker
1
2 : LZIR ( addrblk -
3 LZIPl LZIPl ; \ Double print zipbar
4
5 : WZIP ( addr-blk - )
6 BLPIt'11PSPREIS~ LZIR;
7
8 \ Note: Set column (SETOIL) to n= 1. -3 before printing labels.
9
16 : RLBL ( - 1 \ Return address label
11 RETRDDR SETLRBEL (ADDR) VTRB PCRNCEL ;
12
13 : RLBL ( addr-blk - \ Nailing address label
14 MIZIP SETLRBEL (RDDR) VTAB WCEL ;
15
14
B \ FIG FDIM Rddress
1
2 : FI6 ( - n... 1
2 ,I Forth Interest Group"
4 " P.D. Box 2154"
5 " Oakland, W"
6 "94621-2154"4;
7
8: FD119 ( .. n...
9 " Marlin Duverson, Editor''
10 FIG l+ ;
l!
FORTH and Classic
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Forth Dimensions
(Readability, continued from page 26.)
program code are verysignificant, and the ascenders and
descenders of lower-case letters make for jagged lines that
blur those boundaries.
Sometimes we have to use many abbreviations and
acronyms to get a substantial comment to fit on a line,
since if the comment does not say enough, it may be as
nebulous as the code. Abbreviations and acronyms don't
go over as well in lower-case, since we tend to try to
pronounce them as written instead of recognizing their
meaning. Even when there is plenty of room, I usually use
the same abbreviations and acronyms, just to be consis-
tent. However, in cases where you can forego these
condensations, using lower-case for the comments can
help the eye separate them from the code.
Remember that consistency also contributes to "pretty
code" and helps readability. The numbers 0-9 are always
"capitalsn-why mix them with lower-case a-f in hex
nUmBErS? Many systems will not even recognize lower-
case letters as numbers, so using upper-case will improve
portability, too.
Conclusions
Forth gives an incredible measure of freedom to the
programmer. Since one of the implications is that code
does not have to be readable to run, this flexibility is
sometimes wrongly interpreted as a weakness. In an effort
to make code more maintainable, some companies have
set style standards that their programmers must meet.
These bring up the bottom end, but also have the
undesirable side effect of preventing use of some of the
best strategies.
Producing neat, attractive, readable code ("pretty code")
is not an objective procedure with an exact formula. There
is an art to it. In a way, it's like penmanship; I don't expect
eve~one's to look just like mine, but if a person's writing
is illegible, that is definitely a problem. The continual aim
to achieve greater degrees of readability should be part of
our Forth way of life. I hope this article has helped and
encouraged in that direction.
Laboratory Microsystems, Inc. ..... 16
Miller Microcomputer
Services ......................................... .5
Silicon Composers ......................... 2
L
3 1 March 1994 April