Ufasoft BkLisp - LISP для БК-0010.01, БК-0011М и RT-11
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SVALUE bit structure

 000000: NIL
 1..FIXEND-1:  FIXNUM  biased by FIXOFF
 177777 #UNBOUND (V.U)
 177xxx:  CHARACTER with ASCII code xxx
 xxxxxx < SUBR address: FIXNUM
 Else if binary is xxxxx0 < HEAP address: SUBR
 Else if binary is xxxxx1 < HEAP address: FSUBR
 Else:
   Bits 0..1: Type
	 00: CONS,
	 01: if first WORD is:
		LIST: 	SYMBOL
		FIXNUM:	VECTOR
		SYMBOL:	INTERPRETED FUNCTION (LAMBDA) OR STREAM
	 02: DOUBLE (8 bytes)
	 03: STRING (vector of CHARACTER) max len 255
   Bits 2..1: Address if are in HEAP Range

Structure of objects in Heap

Free block
 -------------------------------
 | BLOCK SIZE (# bytes)        |
 +-----------------------------+
 | NEXT BLOCK PTR              |
 -------------------------------

SYMBOL
  +---------------+
  | Property List | - may include property SYBOL-VALUE
  +---------------+
  |   Function    |
  +---------------+
  | Next in ObList|
  +---------------------------------------+
  | First word of RADIX-50 name or 0      |
  +---------------------------------------+
  |NameLen| Name  or rest of RADIX-50 name|   <- This is also  STRING OBJECT
  |---------------------------------------|
  |  chars ...                            |
  +---------------------------------------+

SIMPLE VECTOR
  +---------------+
  | Len as FIXNUM |
  +---------------+
  | Element [0]   |
  |   ...         |
  |Element [Len-1]|
  +---------------+

ARRAY
  +-----------------------------+
  | -(TotalSize + 1)  as FIXNUM |
  +-----------------------------+
  | Dimensions (list)           |
  +-----------------------------+
  | Element 0                   |
  |   ...                       |
  | Element (TotalSize-1)       |
  +-----------------------------+

STRING
  +-----------------+
  |Len BYTE (0..255)|
  +-----------------+
  | char [0]        |
  |   ...           |
  | char [Len-1]    |
  +-----------------+

LAMBDA
  ---------------------------
  | 'LAMBDA                 |
  +-------------------------+
  | Lambda List             |
  +-------------------------+
  | FUNCTION BODY           |
  +-------------------------+
  | Lexical Environment     |
  +-------------------------+

Console STREAM or STRING-STREAM
  ----------------------------
  | 'STREAM    	             |
  +--------------------------+
  | STRING for STRING-STREAM |
  +--------------------------+
  | Position	               |
  +------------------------------------+
  | ENDPOS / latest char for terminal  |
  +------------------------------------+

FILE-STREAM - 524 bytes (12-byte struct + 512 buffer)
  ---------------------------
  | 'FILE-STREAM            |
  +-------------------------+
  | Filename                |
  +-------------------------+
  | Position                |
  +-------------------------+----------+
  | Low byte: last char,  High byte: 0 |
  +-------------------------+----------+
  | #channel 1..15                     |
  +------------------------------------+
  | length  as UInt16 # of blocks      |
  +------------------------------------+
  | 512 bytes: current block buffer    |
  +------------------------------------+