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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