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RCSNUSP/COBOL

From Rosetta Code

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.

Works with: GNU Cobol version 2.0

snusp.cob:

       >>SOURCE FREE
IDENTIFICATION DIVISION.
PROGRAM-ID. snusp-interpreter.
 
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
REPOSITORY.
FUNCTION find-initial
FUNCTION ALL INTRINSIC
.
DATA DIVISION.
WORKING-STORAGE SECTION.
COPY "dd-program-arguments.cpy".
 
COPY "dd-code-area.cpy".
 
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 instruction-ptr.
11 ip-line USAGE INDEX.
11 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.
000-main SECTION.
001-prepare-code.
CALL "parse-arguments" USING program-arguments
IF code-file-path = SPACES
DISPLAY "No file path specified."
STOP RUN
END-IF
 
CALL "read-code-file" USING CONTENT code-file-path, REFERENCE code-area
 
MOVE find-initial(code-area) TO instruction-ptr (1, 1)
.
010-interpret-code.
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
.
END PROGRAM snusp-interpreter.
 
 
IDENTIFICATION DIVISION.
PROGRAM-ID. parse-arguments.
 
DATA DIVISION.
LOCAL-STORAGE SECTION.
01 num-args PIC 9 COMP.
01 arg-num PIC 9 COMP.
01 arg PIC X(100).
 
COPY "dd-flag-constants.cpy".
 
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.
 
LINKAGE SECTION.
COPY "dd-program-arguments.cpy".
 
PROCEDURE DIVISION USING program-arguments.
ACCEPT num-args FROM ARGUMENT-NUMBER
IF num-args = 0
CALL "display-help"
STOP RUN
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
CALL "display-help"
STOP RUN
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
.
END PROGRAM parse-arguments.
 
 
IDENTIFICATION DIVISION.
PROGRAM-ID. read-code-file.
 
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).
 
LOCAL-STORAGE SECTION.
01 code-file-status PIC 99.
88 end-of-code-file VALUE 10.
 
LINKAGE SECTION.
COPY "dd-code-area.cpy".
 
01 code-file-path PIC X(100).
 
PROCEDURE DIVISION USING code-file-path, code-area.
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."
 
STOP RUN
.
END DECLARATIVES.
 
OPEN INPUT code-file
PERFORM VARYING line-idx FROM 1 BY 1 UNTIL end-of-code-file
READ code-file INTO code-lines (line-idx)
NOT AT END
ADD 1 TO num-lines
AT END
EXIT PERFORM
END-READ
END-PERFORM
 
CLOSE code-file
.
END PROGRAM read-code-file.
 
 
IDENTIFICATION DIVISION.
FUNCTION-ID. find-initial.
 
DATA DIVISION.
LINKAGE SECTION.
COPY "dd-code-area.cpy".
 
01 instruction-ptr.
03 ip-line USAGE INDEX.
03 ip-char USAGE INDEX.
 
PROCEDURE DIVISION USING code-area RETURNING instruction-ptr.
PERFORM VARYING ip-line FROM 1 BY 1 UNTIL ip-line > num-lines
AFTER ip-char FROM 1 BY 1 UNTIL ip-char > 100
IF code-chars (ip-line, ip-char) = "$"
EXIT PERFORM
END-IF
END-PERFORM
 
*> Set position to first char if no initial characters were found.
IF ip-line > num-lines
SET ip-line, ip-char TO 1
END-IF
.
END FUNCTION find-initial.
 
 
IDENTIFICATION DIVISION.
PROGRAM-ID. display-help.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
COPY "dd-flag-constants.cpy".
 
01 Tab-Char CONSTANT X"09".
 
PROCEDURE DIVISION.
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 Tab-Char Flag-Indicator Help-Flag-Char ": Displays this help "
"message."
DISPLAY Tab-Char Flag-Indicator Write-Num-Flag-Char ": Display memory "
"contents as numbers."
DISPLAY Tab-Char Flag-Indicator Read-Num-Flag-Char ": Reads a byte to "
"memory as a number."
.
END PROGRAM display-help.

dd-code-area.cpy:

01  code-area.
03 num-lines PIC 9(4) COMP.
03 code-lines OCCURS 1 TO 1024 TIMES
DEPENDING ON num-lines
INDEXED BY line-idx.
05 code-chars PIC X OCCURS 100 TIMES.

dd-flag-constants.cpy:

01  Flag-Indicator                      CONSTANT "-".
01 Help-Flag-Char CONSTANT "h".
01 Read-Num-Flag-Char CONSTANT "r".
01 Write-Num-Flag-Char CONSTANT "w".

dd-program-arguments.cpy:

01  program-arguments.
03 code-file-path PIC X(100).
03 read-flag PIC X.
88 read-numbers VALUE "N".
03 write-flag PIC X.
88 write-numbers VALUE "N".