RCSNUSP/COBOL
This an SNUSP interpreter written in COBOL. It supports Modular and Bloated SNUSP.
The file path to the code is passed as a parameter to the program. The file is assumed to be a text file with lines having a maximum length of 100 characters. It is also assumed the file will not be more than 1024 lines long.
The memory is a 2048 byte array, the stack has a size of 512 and there is a maximum of 16 threads.
<lang cobol> >>SOURCE FREE IDENTIFICATION DIVISION. PROGRAM-ID. snusp-interpreter.
ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL.
SELECT code-file ASSIGN code-file-path
ORGANIZATION LINE SEQUENTIAL
FILE STATUS code-file-status.
DATA DIVISION. FILE SECTION. FD code-file. 01 code-record PIC X(100).
WORKING-STORAGE SECTION. 01 num-args PIC 9 COMP. 01 arg-num PIC 9 COMP. 01 arg PIC X(100).
01 Flag-Indicator CONSTANT "-". 01 Help-Flag-Char CONSTANT "h". 01 Read-Num-Flag-Char CONSTANT "r". 01 Write-Num-Flag-Char CONSTANT "w". 01 program-flag PIC X.
88 help-flag VALUE Help-Flag-Char. 88 read-num-flag VALUE Read-Num-Flag-Char. 88 write-num-flag VALUE Write-Num-Flag-Char.
01 read-flag PIC X.
88 read-numbers VALUE "N".
01 write-flag PIC X.
88 write-numbers VALUE "N".
01 code-file-path PIC X(100). 01 code-file-status PIC 99.
88 end-of-code-file VALUE 10.
01 num-lines PIC 9(4) COMP. 01 code-area.
03 code-lines OCCURS 1 TO 1024 TIMES
DEPENDING ON num-lines
INDEXED BY line-idx.
05 code-chars PIC X OCCURS 100 TIMES.
01 program-state-flag PIC X VALUE SPACE.
88 program-ok VALUE SPACE. 88 empty-stack VALUE "E". 88 out-of-code-space VALUE "O".
01 memory-area.
03 memory-rows OCCURS 1024 TIMES.
05 memory-cols OCCURS 1024 TIMES.
07 memory-cell USAGE BINARY-CHAR.
07 memory-cell-char REDEFINES memory-cell PIC X.
01 num-threads PIC 99 COMP VALUE 1. 01 threads-data-area.
03 threads-data OCCURS 1 TO 16 TIMES
DEPENDING ON num-threads
INDEXED BY thread-idx.
05 thread-status-flag PIC X VALUE SPACE.
88 thread-started VALUE "Y".
05 call-stack.
07 calls OCCURS 512 TIMES
INDEXED BY stack-idx.
09 direction PIC X.
88 up-dir VALUE "U".
88 down-dir VALUE "D".
88 left-dir VALUE "L".
88 right-dir VALUE "R".
09 ip-line USAGE INDEX.
09 ip-char USAGE INDEX.
05 memory-pointer.
07 row-idx USAGE INDEX.
07 col-idx USAGE INDEX.
01 input-char PIC X.
01 current-thread-idx USAGE INDEX.
PROCEDURE DIVISION. DECLARATIVES. code-file-error SECTION.
USE AFTER ERROR ON code-file. DISPLAY "An error occurred while using " FUNCTION TRIM(code-file-path) DISPLAY "Error code " code-file-status DISPLAY "The program will terminate."
GOBACK .
END DECLARATIVES.
000-main SECTION.
ACCEPT num-args FROM ARGUMENT-NUMBER
IF num-args = 0
PERFORM 300-display-help
GOBACK
END-IF
PERFORM VARYING arg-num FROM 1 BY 1 UNTIL arg-num > num-args
DISPLAY arg-num UPON ARGUMENT-NUMBER
ACCEPT arg FROM ARGUMENT-VALUE
EVALUATE TRUE
WHEN arg (1:1) = Flag-Indicator
MOVE arg (2:1) TO program-flag
EVALUATE TRUE
WHEN help-flag
PERFORM 300-display-help
GOBACK
WHEN read-num-flag
SET read-numbers TO TRUE
WHEN write-num-flag
SET write-numbers TO TRUE
WHEN OTHER
DISPLAY "Flag '" FUNCTION TRIM(arg) "' not recongnized."
END-EVALUATE
WHEN code-file-path <> SPACES
DISPLAY "Argument " arg-num " ignored - only one source code "
"file can be interpreted."
WHEN OTHER
MOVE arg TO code-file-path
END-EVALUATE
END-PERFORM
IF code-file-path = SPACES
DISPLAY "No file path specified."
GOBACK
END-IF
*> Store contents of file into memory.
OPEN INPUT code-file
PERFORM VARYING line-idx FROM 1 BY 1 UNTIL end-of-code-file
ADD 1 TO num-lines
READ code-file INTO code-lines (line-idx)
AT END
SUBTRACT 1 FROM num-lines
EXIT PERFORM
END-READ
END-PERFORM
CLOSE code-file
*> Search for any initial charcters.
PERFORM VARYING ip-line (1, 1) FROM 1 BY 1 UNTIL ip-line (1, 1) > num-lines
AFTER ip-char (1, 1) FROM 1 BY 1 UNTIL ip-char (1, 1) > 100
IF code-chars (ip-line (1, 1), ip-char (1, 1)) = "$"
EXIT PERFORM
END-IF
END-PERFORM
*> Set position to first char if no initial characters were found.
IF ip-line (1, 1) > num-lines
SET ip-line (1, 1), ip-char (1, 1) TO 1
END-IF
*> Interpret the code while there are threads left.
SET right-dir (1, 1) TO TRUE
SET stack-idx, thread-idx, row-idx (1), col-idx (1) TO 1
PERFORM UNTIL num-threads = 0
PERFORM VARYING thread-idx FROM 1 BY 1 UNTIL thread-idx > num-threads
PERFORM 100-move-instruction-ptr
IF out-of-code-space
PERFORM 200-stop-thread
END-IF
EVALUATE code-chars (ip-line (thread-idx, stack-idx),
ip-char (thread-idx, stack-idx))
*> Core SNUSP
WHEN "<" *> LEFT
SET col-idx (thread-idx) DOWN BY 1
WHEN ">" *> RIGHT
SET col-idx (thread-idx) UP BY 1
WHEN "+" *> INCR
ADD 1 TO
memory-cell (row-idx (thread-idx), col-idx (thread-idx))
WHEN "-" *> DECR
SUBTRACT 1 FROM
memory-cell (row-idx (thread-idx), col-idx (thread-idx))
WHEN "." *> WRITE
IF NOT write-numbers
DISPLAY memory-cell-char (row-idx (thread-idx),
col-idx (thread-idx))
ELSE
DISPLAY memory-cell (row-idx (thread-idx),
col-idx (thread-idx))
END-IF
WHEN "," *> READ
IF NOT read-numbers
ACCEPT memory-cell-char (row-idx (thread-idx),
col-idx (thread-idx))
ELSE
ACCEPT memory-cell (row-idx (thread-idx),
col-idx (thread-idx))
END-IF
*> LURD (/ is not used as it is mucks up syntax highlighting.)
WHEN X"5C"
EVALUATE TRUE
WHEN up-dir (thread-idx, stack-idx)
SET left-dir (thread-idx, stack-idx) TO TRUE
WHEN down-dir (thread-idx, stack-idx)
SET right-dir (thread-idx, stack-idx) TO TRUE
WHEN left-dir (thread-idx, stack-idx)
SET up-dir (thread-idx, stack-idx) TO TRUE
WHEN right-dir (thread-idx, stack-idx)
SET down-dir (thread-idx, stack-idx) TO TRUE
END-EVALUATE
WHEN "/" *> RULD
EVALUATE TRUE
WHEN up-dir (thread-idx, stack-idx)
SET right-dir (thread-idx, stack-idx) TO TRUE
WHEN down-dir (thread-idx, stack-idx)
SET left-dir (thread-idx, stack-idx) TO TRUE
WHEN left-dir (thread-idx, stack-idx)
SET down-dir (thread-idx, stack-idx) TO TRUE
WHEN right-dir (thread-idx, stack-idx)
SET up-dir (thread-idx, stack-idx) TO TRUE
END-EVALUATE
WHEN "!" *> SKIP
PERFORM 100-move-instruction-ptr
WHEN "?" *> SKIPZ
IF memory-cell (row-idx (thread-idx), col-idx (thread-idx))
= 0
PERFORM 100-move-instruction-ptr
END-IF
*> Modular SNUSP
WHEN "@" *> ENTER
*> Push current direction and IP location onto call stack
MOVE calls (thread-idx, stack-idx)
TO calls (thread-idx, stack-idx + 1)
SET stack-idx UP BY 1
WHEN "#" *> LEAVE
IF stack-idx <> 1
*> Pop direction and IP location off call stack and
*> advance the IP one step.
SET stack-idx DOWN BY 1
PERFORM 100-move-instruction-ptr
ELSE
PERFORM 200-stop-thread
END-IF
*> Bloated SNUSP
WHEN ":" *> UP
SET row-idx (thread-idx) UP BY 1
WHEN ";" *> DOWN
SET row-idx (thread-idx) DOWN BY 1
WHEN "&" *> SPLIT
*> Create a new thread
ADD 1 TO num-threads
MOVE call-stack (thread-idx) TO call-stack (num-threads)
MOVE memory-pointer (thread-idx) TO call-stack (num-threads)
SET thread-started (thread-idx) TO TRUE
WHEN "%" *> RAND
COMPUTE memory-cell (row-idx (thread-idx),
col-idx (thread-idx)) =
FUNCTION MOD(FUNCTION RANDOM,
memory-cell (row-idx (thread-idx),
col-idx (thread-idx)) + 1)
WHEN OTHER
CONTINUE
END-EVALUATE
IF out-of-code-space
PERFORM 200-stop-thread
END-IF
END-PERFORM
END-PERFORM
.
099-terminate.
GOBACK .
100-move-instruction-ptr SECTION.
EVALUATE TRUE
WHEN up-dir (thread-idx, stack-idx)
SET ip-line (thread-idx, stack-idx) DOWN BY 1
WHEN down-dir (thread-idx, stack-idx)
SET ip-line (thread-idx, stack-idx) UP BY 1
WHEN left-dir (thread-idx, stack-idx)
SET ip-char (thread-idx, stack-idx) DOWN BY 1
WHEN right-dir (thread-idx, stack-idx)
SET ip-char (thread-idx, stack-idx) UP BY 1
END-EVALUATE
.
199-exit.
EXIT .
200-stop-thread SECTION.
*> Shift data from following threads over stopped thread.
SET current-thread-idx TO thread-idx
PERFORM VARYING thread-idx FROM thread-idx BY 1
UNTIL NOT thread-started (thread-idx + 1)
OR thread-idx = num-threads
MOVE threads-data (thread-idx + 1) TO threads-data (thread-idx)
END-PERFORM
SUBTRACT 1 FROM num-threads
SET thread-idx TO current-thread-idx
.
299-exit.
EXIT .
300-display-help SECTION.
DISPLAY "This is a interpreter for SNUSP written in COBOL."
DISPLAY "The file path to the source code should be specified as a "
"command-line argument."
DISPLAY "This program supports the following flags as arguments:"
DISPLAY X"09" Flag-Indicator Help-Flag-Char ": Displays this help message."
DISPLAY X"09" Flag-Indicator Write-Num-Flag-Char ": Display memory "
"contents as numbers."
DISPLAY X"09" Flag-Indicator Read-Num-Flag-Char ": Reads a byte to memory "
"as a number."
.
399-exit.
EXIT .
END PROGRAM snusp-interpreter.</lang>