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Mystic Pascal User Manual 29
8. Procedures and Functions
This section of the manual describes procedures and
functions. Procedures and functions which are used in
Input/Output processing are described in section 9. Multi-
tasking procedures are described in section 7.
Procedure Purpose
--------- -------
DISPOSE deallocate dynamic variable
+ INTR interrupt call
NEW allocate dynamic variable
PACK unimplemented
UNPACK unimplemented
Function Return Value
-------- ------------
ABS absolute value
ARCTAN arctangent
CHR convert integer to character
COS cosine
EXP exponential function
+ FLOAT convert integer to real
+ FRACTION fractional part of real
+1.6 INTSTR convert integer to string
LN natural logarithm
ODD test for odd integer
+ OFFSET offset of a variable
ORD convert ordinal to integer
PRED preceding ordinal
+1.6 REALSTR convert real number to string
ROUND convert real number to integer
+ SEGMENT segment of a variable
SIN sine
SQR square
SQRT square root
+1.6 STRINT convert string to integer
+1.6 STRREAL convert string to real number
SUCC succeeding ordinal
TRUNC convert real number to integer
+1.6 UPCASE convert char to upper case
Section 8: Procedures and Functions
Mystic Pascal User Manual 30
8.1 ABS
ABS( expression )
The ABS standard function returns the absolute value of an
integer or real expression. The result is of the same type as
the input expression.
Examples:
A := ABS( X );
WRITELN( 'ABSOLUTE VALUE IS',ABS( COS( Y )));
B := ABS( X + Y / Z );
Section 8: Procedures and Functions
Mystic Pascal User Manual 31
8.2 ARCTAN
ARCTAN( expression )
This standard function returns the arctangent of a real or
integer expression. The result type is real and is expressed in
radians.
Examples:
WRITELN( ARCTAN( A + 3.14159 ));
NODE.VALUE := OLDNODE.VALUE + ARCTAN( V );
Section 8: Procedures and Functions
Mystic Pascal User Manual 32
8.3 CHR
CHR( integer_expression )
The CHR standard function converts an integer expression
into a character. The result type is char. If the integer
expression is less than zero or greater than 255, a run-time
error occurs.
CHR is often used for sending control characters to output
devices.
Examples:
WRITE( CHR( 12 ));
TAB := CHR( 9 );
CARRIAGERETURN := CHR(13);
LINEFEED := CHR(10);
Section 8: Procedures and Functions
Mystic Pascal User Manual 33
8.4 COS
COS( expression )
The COS standard function returns the cosine of a real or
integer expression whose value is given in radians. The result
type is real.
Examples:
WRITELN( COS( ANGLE ));
NODE.COSINE := COS( N );
WRITELN( COS( VELOCITY / CHARGE ));
Section 8: Procedures and Functions
Mystic Pascal User Manual 34
8.5 DISPOSE
DISPOSE( pointer_variable )
The DISPOSE procedure is used to deallocate dynamic
variables. The pointer_variable addresses a dynamic variable in
dynamic storage. After execution of the procedure the space
released is available for other uses.
Mystic Pascal supports true dynamic storage with auto-
compression. When blocks are freed up, storage fragmentation
occurs -- unused blocks tend to accumulate. Because many blocks
tend to be small, they cannot be immediately reused for another
purpose. When storage becomes short an auto-compression is
initiated by the Pascal system.
Example:
PROCEDURE DISPOSEDEMO;
TYPE
DYNVAR = ARRAY [1..200] OF CHAR;
VAR
POINTER : ^DYNVAR;
BEGIN
NEW( POINTER ); (* ALLOCATE A DYNAMIC VAR *)
(* DO SOME PROCESSING WITH THE DYNAMIC VAR *)
DISPOSE( POINTER ); (* FREE UP THE 200 BYTES *)
END;
Section 8: Procedures and Functions
Mystic Pascal User Manual 35
8.6 EXP
EXP( expression )
The exponential function computes e to the x power, where x is a
real or integer expression. The result type is real.
Examples:
X := EXP( Y );
SHIPVELOCITY := EXP( WARPFACTOR );
Section 8: Procedures and Functions
Mystic Pascal User Manual 36
8.7 FLOAT (Non-Standard Feature)
FLOAT( integer_expression )
The Float function converts integers to real numbers. The
result type is real.
Section 8: Procedures and Functions
Mystic Pascal User Manual 37
8.8 FRACTION (Non-Standard Feature)
FRACTION( real_expression )
The Fraction function returns the fractional part of a real
number. The result type is real.
Section 8: Procedures and Functions
Mystic Pascal User Manual 38
8.9 INTR (Non-Standard Feature)
INTR( interrupt, registers )
The INTR procedure permits access to DOS and BIOS functions
by directly calling interrupt routines. The standard DOS
interrupt is number 33. The interrupt number must be an integer
expression. The registers variable is used to set the 8086
registers on entry and they are stored into the variable on
return from the interrupt routine.
Registers is declared as:
REGISTERS = RECORD
AX,BX,CX,DX,BP,SI,DI,DS,ES,FLAGS : INTEGER
END;
Section 8: Procedures and Functions
Mystic Pascal User Manual 39
8.10 INTSTR (Non-Standard Feature) ** 1.6 **
INTSTR( integer )
The Intstr function converts an integer to a string. The
result type is
PACKED ARRAY [1..6] OF CHAR
The characters are right aligned in the field.
CHART.XAXIS[I] := INTSTR( I * DELTA );
REPORT.YEAR1 := INTSTR( YR );
Section 8: Procedures and Functions
Mystic Pascal User Manual 40
8.11 LN
LN( expression )
The LN function computes the natural logarithm of a real or
integer expression. If the expression is less than or equal to
zero a run-time error occurs. The result type is real.
Examples:
X := LN( Y );
WRITELN( LN( X + SQR(Y)));
IF LN( FACTORBETA ) < 0.1 THEN
WRITELN(FACTORBETA);
A := SQRT( LN(Z));
Section 8: Procedures and Functions
Mystic Pascal User Manual 41
8.12 NEW
Format 1
NEW( pointer_variable )
Format 2
NEW( pointer_variable, tag1,..., tagn )
The NEW procedure allocates new dynamic variables. A block
of dynamic storage of the required size is obtained. The block's
indirect address, not its actual address is stored in the pointer
variable.
After NEW has been executed, the dynamic variable may be
accessed. Dynamic variables remain allocated until specifically
deallocated by the DISPOSE procedure. If a procedure uses NEW to
allocate a dynamic variable, that variable remains allocated
after the procedure ends.
Format 2 contains 1 to n tag fields. These are the fields
specified in the CASE clause of variant records.
Section 8: Procedures and Functions
Mystic Pascal User Manual 42
Example:
(* PROGRAM FRAGMENT TO ALLOCATE A
LINKED LIST OF VARIABLE LENGTH.
THE ROOT OF THE LIST IS A GLOBAL
VARIABLE. NODES AFTER THE FIRST
ARE INSERTED BETWEEN THE ROOT AND
THE FIRST NODE. *)
TYPE
NODE = RECORD
NEXT : INTEGER;
DATA : REAL
END;
VAR
ROOT : ^NODE;
PROCEDURE LINKEDLIST ( COUNT : INTEGER );
VAR
I : INTEGER;
TEMP : ^NODE;
BEGIN
(* ALLOCATE FIRST NODE *)
NEW( ROOT );
(* SET END_OF_LIST INDICATOR *)
ROOT^.NEXT := NIL;
(* ALLOCATE LINKED LIST *)
FOR I := 1 TO COUNT DO
BEGIN
NEW( TEMP );
TEMP^.NEXT := ROOT;
ROOT := TEMP
END
END; (* LINKEDLIST *)
Section 8: Procedures and Functions
Mystic Pascal User Manual 43
8.13 ODD
ODD( integer_expression )
ODD is a Boolean function which returns the value true if
the integer_expression is odd otherwise it returns false.
The expression X is odd if (abs(X) mod 2) equals one.
Examples:
IF ODD(X) THEN TESTFORPRIME(X);
IF ODD(I) THEN I:=I+1;
WRITELN( ODD(Y) );
Section 8: Procedures and Functions
Mystic Pascal User Manual 44
8.14 OFFSET (Non-Standard Feature)
OFFSET( variable )
The Offset function returns the offset of a variable. Used
with the Segment function, this allows passing parameters such as
strings of characters to DOS with the INTR procedure. The result
type is integer.
Section 8: Procedures and Functions
Mystic Pascal User Manual 45
8.15 ORD
ORD( ordinal_expression )
The ORD function converts an ordinal value to an ordinal
number. For example, if
TYPE DAYS = (SUN,MON,TUE,WED,THU,FRI,SAT);
then ORD(TUE) is equal to 2.
Example:
REPEAT
READ(INFILE, CH);
WRITE( CH )
UNTIL ORD(CH) = 26; (* EOF CHAR DETECTION *)
(* ASCII DISPLAY *)
FOR CH := ' ' TO 'z' DO
WRITELN( CH, ' = ',ORD(CH));
Section 8: Procedures and Functions
Mystic Pascal User Manual 46
8.16 PACK and UNPACK
The PACK and UNPACK Pascal standard procedures are not used
in Mystic Pascal. A Pascal program may contain these procedures
but they will be treated as null operations.
Section 8: Procedures and Functions
Mystic Pascal User Manual 47
8.17 PRED
PRED( ordinal_expression )
The PRED function is the inverse of the SUCC function. The
predecessor function returns the ordinal value that is one less
than the input expression.
The PRED of 8 is 7. The PRED of 'T' is 'S'.
Example:
WRITELN( A, PRED(A) );
WRITELN( CH, PRED(CH) );
Section 8: Procedures and Functions
Mystic Pascal User Manual 48
8.18 REALSTR (Non-Standard Feature) ** 1.6 **
REALSTR( real_expression, mode, width, frac );
The Realstr function converts real numbers to strings. All
four parameters must always be present. The mode, width and frac
parameters are all integer expressions. Three conversion modes
are available.
Mode=0 Simple mode - no leading blanks, no trailing zeros,
exponent field is displayed only if required
Mode=1 Floating Point mode - width parameter specifies result
size.
Mode=2 Fixed Point mode - width parameter specifies result size
and frac parameter specifies number of fractional digits.
EDITAREA := REALSTR( AMOUNT, 2, 10, 4 );
FIELD4 := REALSTR( TOTAL, 0, 0, 0 );
Section 8: Procedures and Functions
Mystic Pascal User Manual 49
8.19 ROUND
ROUND( real_expression )
ROUND is a standard function which converts a real
expression to an integer value. If X >= 0 then ROUND(X) is
TRUNC(X + 0.5). If X < 0 then ROUND(X) is TRUNC(X - 0.5).
ROUND( 2.5 ) is 3
ROUND( -2.5 ) is -3
If the real value is too large to be converted to integer
format a run-time error occurs.
Examples:
INT := ROUND( X + Y );
TEMPERATURE := ROUND( THERMOMETERREADING );
PLOTX := ROUND( X / SCALINGFACTOR );
Section 8: Procedures and Functions
Mystic Pascal User Manual 50
8.20 SEGMENT (Non-Standard Feature)
SEGMENT( variable )
The Segment function returns the segment address of a
variable. For global variables this is the same as the User
Area. For local variables this will be a value inside the User
Area. Used with the Offset function this allows passing
parameters such as strings of characters to DOS with the INTR
procedure. The result type is integer.
Section 8: Procedures and Functions
Mystic Pascal User Manual 51
8.21 SIN
SIN( expression )
The SIN standard function returns the sine of a real or
integer expression whose value is given in radians. The result
type is real.
Examples:
WRITELN( SIN( ANGLE ));
NODE.SINE := SIN( N );
WRITELN( SIN( VELOCITY / CHARGE ));
Section 8: Procedures and Functions
Mystic Pascal User Manual 52
8.22 SQR
SQR( expression )
The SQR standard function computes the square of a real or
integer expression. The result type is of the same type as the
input expression.
Examples:
WRITELN( 'SQUARE OF X IS ', SQR(X) );
AREA := SQR( SIDE );
CIRCLEAREA := PI * SQR( RADIUS );
ENERGY := MASS * SQR( LIGHTSPEED );
Section 8: Procedures and Functions
Mystic Pascal User Manual 53
8.23 SQRT
SQRT( expression )
This standard function returns the square root of a real or
integer expression. The result type is real and is always a
positive value. A run-time error occurs if the input expression
is negative.
Examples:
WRITELN( SQRT( A + 3.14159 ));
NODE.VALUE := OLDNODE.VALUE + SQRT( V );
Section 8: Procedures and Functions
Mystic Pascal User Manual 54
8.24 STRINT (Non-Standard Feature) ** 1.6 **
STRINT( string )
The Strint function converts a string to an integer. If the
string does not contain a valid integer as its first non-blank
characters, a value of -32768 is returned.
VALUE := STRINT( INPUTSTRING );
X := STRINT( GETNUM );
Section 8: Procedures and Functions
Mystic Pascal User Manual 55
8.25 STRREAL (Non-Standard Feature) ** 1.6 **
STRREAL( string )
The Strreal function converts a string to a real number. If
the string does not contain a valid real number as its first non-
blank characters, a value of -9.999E-30 is returned.
A := STRREAL( TEXTVALUE );
X := STRREAL( VECTOR[ J ] );
Section 8: Procedures and Functions
Mystic Pascal User Manual 56
8.26 SUCC
SUCC( ordinal_expression )
The successor function is the inverse of the PRED function.
The SUCC function takes an ordinal value and returns the ordinal
value one greater.
The SUCC of 7 is 8. The SUCC of 'S' is 'T'.
Example:
WRITELN( A, SUCC(A) );
WRITELN( CH, SUCC(CH) );
Section 8: Procedures and Functions
Mystic Pascal User Manual 57
8.27 TRUNC
TRUNC( real_expression )
TRUNC is a standard function which converts a real
expression to an integer value. The fractional portion of the
real expression is truncated.
TRUNC(2.5) is 2
TRUNC(-2.5) is -2
If the real value is too large to be converted to integer
format a run-time error occurs.
Examples:
INT := TRUNC( X + Y );
TEMPERATURE := TRUNC( THERMOMETERREADING );
PLOTX := TRUNC( X / SCALINGFACTOR );
Section 8: Procedures and Functions
Mystic Pascal User Manual 58
8.28 UPCASE (Non-Standard Feature) ** 1.6 **
UPCASE( expression )
The UPCASE function is a Mystic Pascal extension which
converts a char or string expression to upper case. The result
type is the same as the input expression type.
Examples:
IF UPCASE( COMMAND ) = 'X' THEN
CMDX;
WRITE( F1, UPCASE(NAME) );
READLN( OPTION );
IF UPCASE( OPTION ) = 'EXIT' THEN GOTO 99;
Section 8: Procedures and Functions
