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1987-09-05
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*
* This program is in the public domain. PostScript is a trademark
* of Adobe Systems.
* Greg Lee, July, 1987.
* U.S. mail: 562 Moore Hall, Dept. of Linguistics
* University of Hawaii, Honolulu, HI 96822
* ARPA: uhccux!lee@nosc.ARPA
*
PS document
Greg Lee, April, 1986
Ps emulates PostScript () Adobe Systems), in a small way.
Interactive input and output takes place in a small window.
The page being composed is shown behind the window in an interlaced
screen with 16 colors. When input is
redirected to come from a file with "ps < programfile", the ps program
in this file is executed before interaction begins.
There is no prompt shown when ps is ready to receive console input.
Default screen coordinates are x = 0 to 639 from the left to the
right of the screen, and y = 0 to 511 from the bottom to the top
of the screen. Considering the units to be points,
that makes the display a nominal 8 8/9" across and 7 1/9" up and down.
Operators do more or less what they do in PostScript, except as
noted below. See PostScript Language: Reference Manual, Adobe
Systems Incorporated, Addison-Wesley, 1985.
Ps has one built-in font named 'simplex', which is stroked. (Data
came from Alan Hershey's data base.)
Types implemented:
integer, real, boolean, string, name, operator
array, mark, dictionary, save, fontID
Operators:
*** stack manipulation ***
pop, exch, dup, copy
index, roll, clear, count
mark
*** math ***
add, div, idiv, mod
mul, sub, abs, neg
ceiling, floor, round [round gives floor of -ddddd.5]
truncate, sqrt
pow, tan, tanh, cosh, sinh (non-standard)
atan, cos, sin
exp, ln, log
*** array ***
array, [, ]
length, get, put
*** dictionary ***
dict
length, maxlength
begin, end
def defined operators are simple objects, not arrays;
"key" must be a name
*** string ***
string the '<..>' syntax is not implemented
length, get, put
*** relational, Boolean ***
eq, ne, ge
gt, le, lt comparisons for numbers only, not strings
true, false
*** control ***
exec leaves anything but an operator on the stack
if, ifelse
for integers only
repeat, loop
exit
stop, stopped untested
countexectack always gives 0, since there is no exec stack
execstack does nothing
quit exit to AmigaDos
start does nothing
*** type, attribute, conversion ***
cvi, cvr no conversion from strings
cvs no range-check is done
*** file ***
file, read, write implemented only for %stdout and %stdin (which
are always the console)
run can't nest run files or have 2 'run' commands
on same line; use in defined procedures will not
work properly, since 'run' merely redirects input
print, =
*** virtual memory ***
save, restore restore merely destroys objects created since
the last save and reuses the memory space they
occupied (in addition to doing a grestore)
*** graphics state ***
gsave, grestore colors are not saved or restored
setlinewidth you get butt linecaps and bevel joins; the joins
are not done properly for concave figures; when
there is non-uniform scaling of the axes, rotation
of the axes is not taken account of
currentlinewidth
setflat, currentflat
setgray there are only 5 levels of grey available, set by
argument: n = 0, 0 < n < .25, .25 <= n < .5, .5 <= n
< .75, .75 <= n <= 1
currentgray
setrgbcolor affects only current foreground pen color;
takes 3 arguments in range 0-15
currentrgbcolor components of current foreground pen color
*** coordinate system ***
translate
scale for Amiga fonts, does not affect sizes of letters;
moves currentpoint (bug)
rotate for Amiga fonts, does not affect orientation
concat, concatmatrix
transform, dtransform
*** path construction ***
newpath, currentpoint
moveto, rmoveto
lineto, rlineto
curveto, rcurveto
closepath
charpath only for simplex font
strokepath affects entire path; lines will always be
one pixel wide
*** painting ***
erasepage
fill, stroke
*** character and font ***
findfont fonts are simple objects, not dictionaries;
'key' can be a string or a name
scalefont for Amiga fonts, must be an available size --
largest is chosen if not scaled -- and also the
font returned is not a new font, just a different
size of the same font (for simplex the font is
new)
makefont only for simplex font
setfont
currentfont
show
stringwidth for Amiga fonts, does not take account of scaling
or rotation; the y coordinate returned is always 0
Non-standard operators:
i {0-7} pencolor set foreground color
i {0-7} penbcolor set background color
i {0-4} penmode jam1, jam2, complement,, inverse
i penpattern
pixel set pixel at currentpoint
i1 i2 i3 i4 box display box with top left corner
at (i1,i2) and lower right at (i3,i4)
any hex name name has value in hex
i1 i2 flood fill area surrounding (i1,i2) with
color, to boundaries of same color;
bombs system if area not enclosed
num greyline argument is in range 0 to 1; 0 causes
Amiga line drawing routine to be used
-- other values set the intensity of
lines drawn by an anti-aliasing
routine, which works best when
rgb colors 0 to 3 are progressively
darker or lighter
Assembly
ps.a main procedure
dict.a systemdict
files.a file io, screen and window initialization
console.a console io for interactive window
ffpa.a conversion between strings and reals
lmath.a 32 bit division and multiplication
control.a 'if', 'repeat', etc.
rmath.a 'add', 'mul', etc.; resident font routines
simplex.chr simplex font data
graphics.a graphics operators
ps.h header for most modules
ps.link 'with' file for linking