Supported functions and statements

The following list applies to the 2.0 version and will (hopefully) be updated in the future.

Supported Statements

• REM and apostrophe comments (' comment)
• LET and implicit assignment without LET
• INPUT ["prompt"], var
• INPUT ["prompt"], var$
• ! var as shorthand for INPUT var
• LINE INPUT #channel, var$
• PRINT
• ? as shorthand for PRINT
• PRINT #channel, ...
• IF ... THEN ... ELSE ...
• multi-line IF ... THEN, ELSEIF ... THEN, ELSE, END IF
• GOTO
• GOSUB + RETURN
• FOR ... TO ... [STEP ...] / NEXT, END FOR
• WHILE ... / WEND
• DIM (for integer arrays)
• OPEN ... FOR INPUT AS #channel
• OPEN ... FOR OUTPUT AS #channel
• CLOSE #channel
• KILL
• GET #channel, [position,] variable
• PUT #channel, [position,] variable
• CLS
• LOCATE row, column
• COLOR foreground, background
• DEF SEG
• POKE address, value
• SELECT CASE, CASE, CASE ELSE, END SELECT
• RANDOMIZE
• RANDOMIZE TIMER / numeric-expression
• XSET handle, index, string-expression
• XFREE handle
• END / STOP / . as shorthand

Supported Control Structures

IF / ELSE

BASCOMP supports single-line and multi-line IF forms in both the traditional line-numbering and the QB mode.

Single-line form:

IF A > 10 THEN PRINT "HIGH" ELSE PRINT "LOW"

Multi-line form:

IF A > 10 THEN
  PRINT "HIGH"
ELSEIF A = 10 THEN
  PRINT "TEN"
ELSE
  PRINT "LOW"
END IF

Boolean IF expressions support AND, OR, and NOT in supported comparison contexts.

SELECT CASE

SELECT CASE supports numeric selection logic:

SELECT CASE A
  CASE 1
    PRINT "ONE"
  CASE 2
    PRINT "TWO"
  CASE ELSE
    PRINT "OTHER"
END SELECT

FOR / NEXT / END FOR

Counted loops are supported, including nested loops and optional STEP values.

FOR I = 1 TO 10 STEP 2
  PRINT I
NEXT I

END FOR is also recognized as an explicit loop terminator form.

WHILE / WEND

WHILE A < 10
  A = A + 1
WEND

Subroutines

Subroutines are supported through GOSUB and RETURN.

Supported Data Types

Numeric Variables

Numeric variables store signed 16-bit integer-style values.

String Variables

String identifiers end with $ and use counted string representation in the runtime.

Indexed Numeric Arrays

DIM creates indexed numeric arrays using syntax such as A(I). Small arrays are stored internally; larger arrays can be backed by external DOS memory through the runtime array support.

DIM A(10)
LET A(1) = 5
LET X = A(1)

External String Arrays

External string arrays are available through:

• XALLOC(count)
• XALLOC(count, maxLength)
• XSET handle, index, string-expression
• XGET$(handle, index)
• XFREE handle

Supported Expressions

Numeric Expressions

Numeric expressions support:

• decimal constants and variables
• hexadecimal constants with &H...
• numeric array elements such as A(I)
• parentheses
• unary + and unary -
• +, -, *, /, \
• MOD
• XOR
• AND
• OR
• exponentiation with ^
• numeric function calls

String Expressions

String expressions support:

• string variables
• string literals
• string concatenation with +
• string function calls
• DATE$, TIME$, INKEY$, and INPUT$

BASCOMP 2.0 continues the expanded internal string-expression handling introduced before version 2.0. The compiler uses a larger internal string context stack and additional temporary string buffers for nested string functions and concatenations.

Supported Comparisons

The following comparison operators are supported in IF expressions: =, <>, <, >, <=, >=.

Comparisons work for both numeric values and supported string expressions, depending on context.

Supported Functions

Numeric and Conversion Functions

• LEN(string)
  Returns the length of a string.
• VAL(string)
  Converts a string to a numeric value.
• ASC(string)
  Returns the character code of the first character.
• EOF(channel)
  Returns the end-of-file state for a file channel.
• EXIST(string)
  Tests whether a file exists.
• INSTR(string, pattern)
  Searches for a substring and returns its position.
• INSTR(start, string, pattern)
  Searches for a substring starting at a specific position.
• ABS(number)
  Returns the absolute value.
• SGN(number)
  Returns -1, 0, or 1 depending on the sign of the value.
• RND(number)
  Returns a pseudo-random number in the supported runtime range.
• INT(number)
  Returns the integer value.
• SQR(number)
  Returns the integer square root.
• MIN(a, b)
  Returns the smaller value.
• MAX(a, b)
  Returns the larger value.
• TIMER()
  Returns the number of seconds since midnight modulo 65536.
• EXEC(program$, args$)
  Starts a DOS child program and returns 0 on success or a DOS error code.
• CPUID()
  Detects the CPU class and returns the runtime CPU identifier. See the runtime for details.
• PEEK(address)
  Reads a byte from the active DEF SEG segment.
• XALLOC(count) / XALLOC(count, maxLength)
  Allocates an external string array and returns a handle.

String-Producing Functions

• CHR$(number)
  Builds a one-character string from a character code.
• LEFT$(string, count)
  Returns the left part of a string.
• MID$(string, start, count)
  Returns a substring.
• RIGHT$(string, count)
  Returns the right part of a string.
• LTRIM$(string)
  Removes leading spaces.
• RTRIM$(string)
  Removes trailing spaces.
• TRIM$(string)
  Removes leading and trailing spaces.
• UCASE$(string)
  Converts ASCII lowercase letters a to z to uppercase.
• STR$(number)
  Converts a numeric value to a string.
• XGET$(handle, index)
  Reads a string from an external string array.
• DATE$
  Returns the DOS date in mm-dd-yyyy format.
• TIME$
  Returns the DOS time in hh:mm:ss format.
• INKEY$
  Returns a non-blocking keyboard input string.
• INPUT$
  Reads a string from standard input.

File I/O

Text file I/O is supported through:

• OPEN
• CLOSE
• PRINT #
• LINE INPUT #

Binary file I/O is supported through:

• GET
• PUT

File channels 1 to 9 are supported.

OPEN supports:

• FOR INPUT
• FOR OUTPUT

KILL deletes a file. EXIST() checks whether a file is present.

The runtime retains buffered byte output for PUT; buffered binary output is flushed when required by handle changes, seek operations, close operations, and mixed text/binary output paths.

Screen Output

Standard text output is supported through PRINT.

Additional screen control is provided by:

• CLS
• LOCATE
• COLOR

When screen output support is active, runtime text output to the console can use BIOS text output with the active COLOR attribute.

Memory Access

BASCOMP 2.0 supports a compact BASIC-style memory access subset:

• DEF SEG = expression sets the active segment used by PEEK and POKE.
• DEF SEG resets the active segment to the program segment.
• PEEK(address) returns the byte at the active segment and offset.
• POKE address, value writes a byte to the active segment and offset.

Values written by POKE must fit into a byte (0..255).

Date, Time, Keyboard, EXEC, and CPU Support

BASCOMP 2.0 includes runtime support for:

• DATE$ using DOS date services,
• TIME$ and TIMER() using DOS time services,
• INKEY$ using enhanced BIOS keyboard calls where available,
• EXEC() for launching DOS child programs,
• CPUID() for CPU-class detection.