sbref.txt

smallbasic for linux

Generic
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Limits:
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Max. length of 
   code text line: 511 chars
Max. keyword length: 32 char
Max. num. of parameters: 64
Max. arrays dimentions: 4
Numeric value range: 64b FPN
Max. string size: 32KB
Max. number of file handles:
  PalmOS: 16
  Other: 256
INPUT (console only)
  limit: 255B per call.
  up to 16 variables.
Max. number of colors: 16
Max. bytecode size: 64KB
  (by using CHAIN you can
  run progs > 64KB)
Background sound queue
  size: 256 notes

System events are checked
every 50ms

PalmOS:
  Be careful with memory
  there is no too much.
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Variables:
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There is no data types. All
user variables (include
arrays) are 'VARIANT'.

SB uses internaly 3 types
1. Integer (32bit)
2. Real    (64bit)
3. String  (<32KB)

Variable names can use any
alphanumeric characters,
and the '$'. The first char
of the name cannot be
a digit.
The symbol '$' is supported
for compatibility. Its use
is meanless.

Example:

a="123"
a$=1
? a<>a$
REM displays 1 (true)
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System Variables:
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OSVER  - OS Version
OSNAME - OS Name
SBVER  - SmallBASIC Version
PI     - 3.14..
XMAX,YMAX
       graphics display max.
BPP    - Bits per pixel

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Operators (by priority):
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( )       = parenthesis
-         = unary
^         = power

* / \     = mul, div, idiv
% MOD     = modulus

+ -       = add, sub

=> =<  = 
>= <= <>  = compare

AND & OR  |
NOT ! XOR ~
          = logical

:         = EOL

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Base convertion:
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&H|0x hex. ex: 0x1F + &H1F
&o|0o oct. ex: 0o33 = &o33
&b|0b bin. ex: 0b11 = &b11
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Meta-commands:
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#!...
  Used by Unix to make
  SB source runs as script
  executable

#sec:section name
  Used internaly to store
  the section name

  DON'T USE IT

#inc:"file"
#inc:file
  Used to include a SB
  source file into current
  BASIC code

Example:
...
#inc:"mylib.bas"
...
MyLibProc "Hi"
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Subroutines/Functions:
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SUB name
  [([BYREF] par1 [,
  ...[BYREF] parN)]]

  [LOCAL var[, var[, ...]]]
  [EXIT SUB]

END

FUNC name
  [([BYREF] par1 [,
  ...[BYREF] parN)]]

  [LOCAL var[, var[, ...]]]
  [EXIT FUNC]

  name=return-value
END

Use function's name
to return the value.

Nested procedures/functions
are allowed (like Pascal).

Example:

FUNC f(x)
  FUNC f11
    FUNC f21
	f21=21
	END
  END
  FUNC f12
  f12=12
  END

? f11
? f21: REM ERROR
f=x+f11+f
END

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The parameters are 
'by value' by default.
Passing parameters by value
means the executor makes
a copy of the parameter to
stack. The value in caller's
code will not be changed.

Use BYREF keyword for
passing parameters 
'by reference'. 
Passing parameters by
reference means the
executor push the pointer
of variable into the stack.
The value in caller's code
will be the changed.

Example:

' 'by value'
SUB F(x)
x=1
END

x=2
F x
? x:REM displays 2

' 'by reference'
SUB F(BYREF x)
x=1
END

x=2
F x
? x:REM displays 1
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Use the LOCAL keyword for
local variables.

LOCAL creates variables
(dynamic) at routine's
code.

Example:

SUB MYPROC
LOCAL N:REM LOCAL VAR
N=2
? N:REM displays 2
END

N=1:REM GLOBAL VAR
MYPROC
? N:REM displays 1
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You can send arrays as
parameters with ().

When using arrays as
parameters its better to use
them as BYREF; otherwise 
their data will be
duplicated.

Example:
SUB FBR(BYREF tbl())
? FRE(0)
...
END

SUB FBV(tbl())
? FRE(0)
...
END

' MAIN
DIM dt(128)
...
? FRE(0)
FBR dt()
? FRE(0)
FBV dt()
? FRE(0)
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On a multi-section 
applications sub/funcs needs
declaration on the main
section.

Example:
#sec:Main
declare func f(x)

#sec:another section
func f(x)
...
end
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Passing & returing arrays,
using local arrays.

Example:

func fill(a())
  local b(), i

  dim b(16)
  for i=0 to 16
    b(i)=16-a(i)
  next
  fill=b()
end

DIM v(4)
v()=fill(v())
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Statements:
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'|#|REM ...

Remarks.
The # can be used as remarks
only in the first pos. of
the text line.
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[LET] var = expr

Assign 'expr' to variable
'var'.

Example:
z=1
z="Change to string"

DIM v(4)
v2()=v()
z=v():REM make z copy of v()
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CONST var = expr

Assign 'expr' to variable
'var' and make it READ-ONLY.
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DIM var( [lower TO] 
             upper [, ...])

Creates an array.
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[LABEL] label

Defines a label. There are
two kinds of labels. Numeric
and alphanumeric.

Numeric labels does not 
needed the keyword LABEL,
but alphanumeric does.

Example:
1000 ? "Hello"

LABEL AlphaLabel
? "Hello"
...

GOTO 1000
GOTO AlphaLabel
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GOTO label

Branches to a specified
label.
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GOSUB label - RETURN

Branches to an old-style
subroutine. The subroutine
returns to GOSUB's next
instruction with RETURN.
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ON expr GOTO label-list
ON expr GOSUB label-list

Branches to one of the 
several locations, depending
of the value of the 'expr'.
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FOR var = expr TO expr
         [STEP expr] - NEXT

Repeats a code block for
a specified number of times.
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WHILE expr - WEND

WHILE/WEND code block, loops
while 'expr' is true.
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REPEAT - UNTIL expr

REPEAT/UNTIL code block, 
loops while 'expr' is false.
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IF expr  [THEN] -
         [ELSE|ELIF|ELSEIF]
         - ENDIF|FI

Executes a code block
depending on specified
conditions.
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IF expr THEN
          [num-label]|[...]
   [ELSE [num-label]|[...]]

Old-style inline-IFs.
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STOP|END

Stops the program execution.
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RESTORE label
READ var[, var ...]
DATA n[,n ...]

DATA specifies values to
be read by READ.

RESTORE specifies the
position of the next
data to be read.

READ reads values from
current data position.

Example:

RESTORE MyDataBlock
FOR I=1 TO 3
	READ v
	PRINT v
NEXT
END

LABEL MyDataBlock
DATA 1,2,3
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ERASE var1[, var2[,
  ... varN]]

Frees the memory used by the
specified arrays or 
variables. 
After that these variables
turned to simple integer
with value 0

Example:
DIM x(100)
...
? fre(0)
ERASE x
? fre(0)
? x(1):REM ERROR
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EXIT [FOR|LOOP|SUB|FUNC]

By itself exits from last
command block (loop, 
for-loop or routine)

FOR - Exit from the last
  FOR-NEXT loop

LOOP - Exit from the last
  WHILE/REPEAT loop

SUB - Return from the
  current routine

FUNC - Return from the
  current function