LONG INTEGERS

UCSD Pascal allDws integers of 0p to 36 digits.

3.3 3 for details ~egarding long int~ge~s.

Se~ section

2.;;': 21 UNITS

UCSD Pascal now ~upports the modularity concept of UNITs. See sec t ion 3. 3. 2 for de -t ail ^{S l'} e 9 ⁱ³ r din 9 UN I T ~ .

2.2.22 SUMMARY OF U. C.S. O. INTRINSICS INTRINSIC SECTION #

2. 1. 2

BLOCI-<.WR I TE 2.1.2

Page 156

DESCRIPTION

Furtction whi~h reads a variable number of blocks 'rom an untyped fjl~.

Function which writes a variable number of blocks from an untyped file.

CLOSE 2. 1.2

STRING intrinsic used to concatenate strings together.

STRING intrinsic used to d~lete characters from STRING variables.

G~aphics intrinsic for use on the Terak 8510a.

Graphics intrinsic for use on the Terak 8S10s.

Intrinsic used to exit PROCEDURES cleanly.

Procedure used for ^cu~sor addressing whose two STRING intrinsic which Teturn~ the dynamic length

Used to ^m~~k the current top of the heap in dynamic

RELEASE SEEK SrZEOF

STR

TIME

TREESEARCH UNITBUSY

UNITCLEAR

UNITREAD UNITWAIT

UNITWRITE

Paqe 158

2. 1.3

2. 1.2 2. 1.6

2. 1. I 2. 1.6

2.1.2

2.1.2

2.1.2

2.1.2

2.1.2

Intrinsic used tOT'elease memory occupied by

variables dynamically allocated in the heap.

Used far random accessing of records withing a file.

Function returning the number of bytes allocated to ~l v~riable.

Procedure to convert long integer into string.

Function returning the time since last bootstrap of system. (returns z~ro if microcomputer has no real time clock)

Routine used solely ^by the Pascal compiler.

Law level i~triniic For det~rmining tha status of a peripheral device.

Low level intrinsic to cancel 1/0 from a peripheral device.

Low level intrinsic for reading from a peripheral device.

Low level intrinsic for waiting until a peripheral device has completed an I/O operation.

Low level intrinsic used for writing to a peripheral device.

************************************ ***************

*

^DRAWLINE AN IMPLEMENTOR'S GUIDE

* *

Section 3.1

*

************************************ ***************

VeT'S i on I. 5 September 1978

The DRAWLINE Intrinsic uses an incTemental technique to plot line segments on a point-addressable matrix. The algorithm guarantees a best (least squares) approximation to the ^de~ired line. In general this

appr'f.}:cifHatiQn J.s n,~;i,~ ufd,qtie. DF~t..!LIf·iE (T\~;H; pick diffe!"erit

i'epi'e-S\?nt~t:ions 'tOT' d line depfi'nding on the ~tQT'ting point. (This could be C ^Q'1" 1" e c ted 1.1 \J a 1 W-3 Y ss. tar tin 9 at the same end of the 1 i n e. ) No 1'" a n 9 e

chec~ing is performed an parameters passed to thi~ intrinsic,

The alQo~ithm IS essentially the one described in Newman and

Sp~oul, P~t~ci~19s of Intersttive Computer Graphics a~ the Digital DiFfeTentiel AnAlyzer It has been modified to perform only integer 9Tithmetic P~~c~l SQUTee cnde is included b~lDW, The procedure first

rl e t e-T m i 'i -:? d '\l,! h e t h ^{f; 'f'} the 1 i 11 ~ ;1) i l l h f.' ,~i C':' ~ h (') 1" i 7 c.~ 1; t,~ 1 ,)"r~ \? f~ T' ,t i c ~ 1 . ! n t h e d :i. s r_ u ;'~ ':: i ^i'1 n b • .£.' 1. <j W I we a saw in e the h C i' i z 0 n t ^B 1 c. 1:1 s e : v e r t i ca 1 i IS S i mil a r .

There will be DELTAX points p10t~~d with horIzontal increment of 1 ~ach" The vertic~l increm4?nt will be. ,\BS (DELTAY I DELTAX)

<=

^1.

The Y coordinate arithmetic is scaled by DELTAX to eliminate fractions.

An additional savings in execution time has be~n gained by maintaining

t h ^2:::; L~J 'f' ,',2 '::.; S .) f ":" ~~ ::' p 'f' h~ V i ^t) u ~:.. pet:,,\ t . ~ n d doing ⁰ n 1. y .a d d i til) n and

subtraction to reach the next point to be plotted.

The Hp.,D/\F~p~ .. "lc.tion i~ C':t.l!1'i/:ili,:,,:,:::tc7d . .:::s twa :Lr:te-T'se·:ting lines may

hay~ no plotted pU1nts in common. Tha detection conditIon is either (1) t i H? C Q (;1 put e d p cd n t i:; T Ii l.iE 1 D T' <~?) bot h t h eo n e ^{x ,t} tH',H" i Z 0 n t d 1 and the n e ^'f. t ^',! e r t :i c. e 1 yed ⁿ t saT' e T R UF.:: Con d i t ion ( 2 ) could be weakened; when

t ^{h li:'!} i n e :\ s m C11 e ;.; C f' 1, '! I) n tal' ; en 1 lj t Ii e n ext VeT' tic. a l p 0 i n t need b e checked.

Ref e i' .t; Q S .2 C to: i Q it 2, 1. .1- for .~ ct e E! s:: r' i p t 1. 0 n 0 of the paT' a m e 't e r e a l l i n 9 seq u e nee.

Page 159

PROCEDURE DRAWLINE (VAR RANGE: INTEGER, VAR SCREEN: SCREENTYPEi ROWWIDTH, XSTARTI YSTART, DELTAX~ DELTAYJ INK: INTEGER)j

VAR X. V, XINC,· VINe. COUNT: !Nl'£GFP,

PROCEDURE DOFORY; C*MORE VERTICAL*) VAR ERROR, 1: INTEGERi

BEGIN

ERROR ;= DELTAY DIV 2;

I :

=

^DELT?\Yi

REPEAT

ERROR := ERROR + DELTAX;

IF ERRDR :'.,:-:; DEL TA'Y

THEN BEGIN EHROR ::~ E'RHOR .- DELTAY::

x

Y :::: Y + VINCI' DRAJ...'DOTi

I := I - 1;

UNTIL I :: Oi END (*DOFORY*) ;

BEGIN <*DRAWLINE*) X :;;.; XSTAHTi IF DELTAX

<:

0

THEN BEGIN XINC

EL SE X INC ::.: 1 i

Y :::: YSTART;

IF DELTf"lY <: Q

THEN BEGIN Ylr~C

ELSE Y INC :

=

1 i

COUNT :~.;;; OJ

-1; DELTf~X ··nrL TAX

--1, DELrAY - ·-l)~.LTAY

E.L SE {jUF OR Y ;

x

⁺ XINC ^END;

END

END

IF DELTAX

>=

DELTAY THEN DOFORX

IF IN~ = 4 (~nADAR*) THEN RANGE CDU~ .. rr;; <*HIT THE LIMIT GIVEN*>

END <*DRAWLINE*)i

Page 161

-

Notes-**************** ***************

Fa 11 ow i n g the aT' l' at) 0 of n a me s i s an aT' ra y ^I ag a i n 16 til 0 1" d ^$ 1 on 9 ^I

of state descriptors. The values in this array indicate what kind of segment is at the described location. The values far this array, at present, are: LINKED,HOSTSEGtSEGPROC.UNITSEG,SEPRTSEG.

The rem,:lindeT' of the block, 144 \uor'ds, is reserved for future use by later versions of the system. ^The fermat of the fi~st block will mast probably change completely foT' version 11.0.

Pt~ge 164·

~-*{HH**·i:'*·l:HHH~·,*·***·******Fi-R*j:Hi· ,***************~*

*

SEGMENT PROCEDURE NOTES

* *

Section 3.3.1

*

*******~*******************

*****************

Version 1,5 September 1978

Declarations of SEGMENT procedures and functions are identical to standard Pascal procedures and functions except they are preceded by

tiH.~' l"e's€t'fved ulord 'SEGt'1ENT', fOl' ei:,~mpJ~:

SEGMENT PROCEDURE !NITIALIZE~

BEGIN

(* PASCAL codE *) ENDi

Program behavior diff~rsl however~ as code and data for a SEGMENT procedure (function) are in memory only while there is an active invocation of that prCfAdure,

The usel' mialj now put large pieces of one-time code, ego

in:itial i :u~tj on corle, into a SEGMENT pr'oceduT'e. After performing the initialization. for eyamplel th~ new-useless code is taken out of memory thus increasing the available memory space.

Furthe~more the user ma4 now compile his/her program in chunks,

sp~~:i~icallu in SEGt"1ENTS. Ttl{'; LINV.ER program (described in Section 1. 8) c: ^at n L c' ^l.,.i s e ~1 t <J 1 ink t ^(J get ffH:' j ' t b~: s e p d rat e s e 9 me n t s t (j P r-c due e on e large code f:ile.

Requirem2nts and limitations:

The disk which holds the codefile fer the program must be on-line (and in the same drive as when the program wae started) whenever one of SEGMENT protedUTe~ i~ to he c211ad Otherwise the sy.tem will attempt to retrieve and execute whatever information now occupies that particular 11Jcati..on on the d1<slc· u5ual1tJ hJlth verlJ displeasing and cErtaInly Ln&xpected results.

available to the user

SEGMENT procedures reust be the f1rst pro~eduTe declarations containing code-generating statements.

For furth~r details and exampJes see Section 3. 5~ INTRODUCTION TO THE P!~SC:AL PSE:UDD Mt;CH!NE

Page 165

-

Ntd.:;e~,-~age 166

****R*****~**~********************

*****************

~;, L T f.!V.!\C:: Tn [';~ TERfU\!. L Y COMP I L.ED

* *

Se c t ion 3. 3. 2

*

*

AND ASSEMBLED ROUTINES

* * *

********************************** *****************

Vtn"sion 1. 5 Se p temb En" 1978

EXTERNAL COMPILATION UNITS

The ucsn Pas,cial 1. 5 stjstem SUppOl"ts a facility foT' integrating externally compiled and assembled routines and data st~uctures. Use of separately compiled st~uctures allows the user to create files of

of T' e G. iJ f~ n t 1 U USE' d l" 0 u t j 11 C· 'S . [\ f t t? r- ^d s t; "[" u c t; U "f' f' i '!. C em p j 1 e d ^I the u '5 era d d s i t to a library, using the library maintainer. Files that reference that structu~e need not compile i t directly into their code file,

l' a the l' J t ~~ E' 1 i n ir: e T' cop 3. 9 S the e xis tin 9 r.: c ~j f~' i n t o t h e h 0 s t e o d e of i 1 e . Separate compilation or assembly is supported in these areas: between

portions of programs written in Pascal; between assembly language T'ctrt:ines ar,tj Pa~)c,31 hosts; .3nd fin~~11y, bf~tl!.:een assembly language

routin~s. Each o¥ these areas is discussed in turn by the following sections.

3, 3. 2 1 PASCAL. TO PASCAL LINft,AGES - - UNITS

A UNIT IS a group of interdependent proceduresl functions, and associated data st~uctures which perform a specialized taSk. Whenever

this task 15 needed within d prograffit the program indicates that it USES the UNIT. A UNIT consists of two parts, the INTERFACE pa~t, which dec 1 a j . e s r: n n ~ t ~~ n t <,:;- t tj P f~S j V a:\ r i s b 1 e s .~ pro C eo d l.l't' e s a 1"1 d of u net ion s t hat are public and can be used by the host program. and the IMPLEMENTATION

paTt~ which declares constants! types, variables .. procedures and

functions that ~re private, These are not available to the host program and are used b~ the UNIT. The INTERFACE pa~t declares how the program will communicate with the UNIT while the IMPLEMENTATION part defines how the UNIT will accomplish its task.

TURTLEGRAPHICS ( example B ) is a UNIT which enables the user to draw pictures using a graphics turtle. The INTERFACE consists of procedures like MOVE, TURN, and PENCOLOR} which allow the user to move the turtle and change ~olo~s. TURTLEGRAPHICS also employs DRAWLINE, an externally assembled procedurei to draw the lines and the tu~tle.

A prog~am that uses TURTLEGRAPHICS has no need for DRAWLINE, and, conse~uentlyj DRAWLINE is private to that UNIT.

Page 167

PROGRAM DRAWPOLYGON;

USES TURTLEGRAPHICS;

VAR I: INTEGER;

SIZE/NUMSIDES: INTEGER;

BEGIN

INITTURTLEi <* Initialize the UNIT's variables

*>

WRITE{'What size pclygon~/)j

READf_N(SIZE) i

WRITE(~How many sides?i)j

READLNCNUMSIDES);

FOR 1:=1 TO NUMSIDES DO

Bf:~rN

END.

MOVE ( S J Z E ) j

TURf\! (360 D I \/ hP')MS I DES);

ENDj

A program must indicate the UNITs that i t USES before the LABEL declaration part Q~ the program. At the occu~rence of a USES

statement, the compiler references the INTERFACE part of the UNIT as though it were part of the host text itself Therefore all public

con s t (.1 n t 5 . t Y P t?!.) : va r i ~ b 1 e S 1 fun c: t i en 5 J and p ·r c t: e d lJ T' f? 5 are 9 1 Q b a 1 . Name conflicts may a~ise if the U5~r defin~s an id~ntifier that has alre~dy

been defined by the UNIT. PTocedur~s and function~ may not USE UNITs localllJ.

Paoe 168

UN I T rUPTLJ:':~CRAPHT. CSi I ^~.rn::·? F !\ ~ F

PRoc!:~n! . .InE IN I TTI.IRTLEi

PHOCEDURE TURN ( HFLANGLE.. In t P.g e 1" ) ;

PROCEDURE MDVE( REL.DISTANCE: !nt~gE~' )i

PRDCEDURi-: MDV~.TO( X, 'y" Integer ) i

PROCEDURE TURNTO( ANGLE, Intege'r' )i

PROCEDlJRE PENGOL.OR ( PCOLOR, TGCOLOR ) i

! ~1PLEMEN T'A r ION

TER xsr ZF = 319:

"fER'y'S:: 7E - 2,39;

TYPE

SCREEN

=

^{Pi.=:!C ~ed}

,";T'T'dY TERXSIZE, O .. TERVSIZEJ of Boolean;

VAR

<*

Private Y~riables *) TGXPOB: Integer;

TGYPClS: Integer;

TGHEADING: !nteger~

TGPEN: TGCDLOR;

1; d: Int.eger-j S: SCREEN;

(* Externally clssembled ~rocedure *)

P~OCED1)RE DRAlfJL,INE( Var RADI~R. Integer; Val'S: SCREENi

ROW, XO, VOl DX, DY, PEN: Integer );

EXTERNALi

<*

External declaration * )

PROCEDURE INITTURTLEi

BE(~ IN

Fillchar-( SCREEN_, SilHOf(SCREEN), 0 ) ;

UnitwTite( 3, SCREEN, 63 );

HEADING : = 0;

TGXPOS .-- 0;

TGVPOS 0;

ENDi

PROCEDURE MOVEi (* Public procedu~el pa~ameters declared above

*>

BFGr,lN

MOVETO{ Round(TURTLEX + DIST*Cos(TURTLEANGLE/RADCONST), RoundCTURTLEY + DIST*Sin(TURTLEANGLE/RADCONST) );

END;

PROCEDURE MOVETOi

VAR R: I n t e 9 e r'-i

BEGIN

DRAWLINEC R} 91 20! 160+TURTLEXi 120-TURTLEY.

Im Dokument 3 System 1 (Seite 153-166)