Base64 konvertering

Nu er jeg jævnt dårlig til COBOL, men jeg kender base64.

Prøv og se om du kan shine det her lidt op:

IDENTIFICATION DIVISION.
PROGRAM-ID. B64DECODE.

ENVIRONMENT DIVISION.

DATA DIVISION.
WORKING-STORAGE SECTION.
01 I PIC 9(1) BINARY.
01 L2 PIC 9(3) BINARY.
01 ARRAYS.
    03 B6 PIC 9(3) BINARY OCCURS 4.
    03 B8 PIC 9(3) BINARY OCCURS 3.
LINKAGE SECTION.
01 S PIC X(100) DISPLAY.
01 RES PIC X(100) DISPLAY.
01 L PIC 9(3) BINARY.

PROCEDURE DIVISION USING S, RES, L.
MAIN-PARAGRAPH.
    MOVE 0 TO L
    PERFORM VARYING L2 FROM 1 BY 4 UNTIL S(L2:1) = " "
        PERFORM VARYING I FROM 1 BY 1 UNTIL I > 4
            MOVE FUNCTION ORD(S(-1+L2+I:1)) TO B6(I)
            SUBTRACT 1 FROM B6(I)
        END-PERFORM
        PERFORM VARYING I FROM 1 BY 1 UNTIL I > 4
            IF B6(I) >= 48 AND B6(I) <= 57 THEN
                COMPUTE B6(I) = B6(I) + 4
            ELSE IF B6(I) >= 65 AND B6(I) <= 90 THEN
                COMPUTE B6(I) = B6(I) - 65
            ELSE IF B6(I) >= 97 AND B6(I) <= 122 THEN
                COMPUTE B6(I) = B6(I) - 71
            ELSE IF B6(I) = 43 THEN
                COMPUTE B6(I) = 62
            ELSE IF B6(I) = 47 THEN
                COMPUTE B6(I) = 63
            ELSE IF B6(I) = 61 THEN
                COMPUTE B6(I) = 0
            END-IF
            END-IF
            END-IF
            END-IF
            END-IF
            END-IF
        END-PERFORM
        COMPUTE B8(1) = B6(1) * 4 + B6(2) / 16
        COMPUTE B8(2) = FUNCTION MOD(B6(2), 16) * 16 + B6(3) / 4
        COMPUTE B8(3) = FUNCTION MOD(B6(3), 4) * 64 + B6(4)
        PERFORM VARYING I FROM 1 BY 1 UNTIL I > 3
            ADD 1 TO B8(I)
            MOVE FUNCTION CHAR(B8(I)) TO RES(L+I:1)
        END-PERFORM
        ADD 3 TO L GIVING L
    END-PERFORM
    EXIT PROGRAM.

Det er testet med Digital Cobol på VMS.

Men jeg vil tro at det kan porteres til IBM COBOL på z/OS uden det helt store besvær.

Ups. Der er lige en lille fejl.

Der skal traekkes antal = til sidst i input fra L ellers faar man trailing zero bytes.

Jeg laver lige en ny version senere.

IDENTIFICATION DIVISION.
PROGRAM-ID. B64DECODE.

ENVIRONMENT DIVISION.

DATA DIVISION.
WORKING-STORAGE SECTION.
01 I PIC 9(1) BINARY.
01 L2 PIC 9(3) BINARY.
01 EQ PIC 9(1) BINARY.
01 ARRAYS.
    03 B6 PIC 9(3) BINARY OCCURS 4.
    03 B8 PIC 9(3) BINARY OCCURS 3.
LINKAGE SECTION.
01 S PIC X(100) DISPLAY.
01 RES PIC X(100) DISPLAY.
01 L PIC 9(3) BINARY.

PROCEDURE DIVISION USING S, RES, L.
MAIN-PARAGRAPH.
    MOVE 0 TO L
    PERFORM VARYING L2 FROM 1 BY 4 UNTIL S(L2:1) = " "
        PERFORM VARYING I FROM 1 BY 1 UNTIL I > 4
            MOVE FUNCTION ORD(S(-1+L2+I:1)) TO B6(I)
            SUBTRACT 1 FROM B6(I)
        END-PERFORM
        MOVE 0 TO EQ
        PERFORM VARYING I FROM 1 BY 1 UNTIL I > 4
            IF B6(I) >= 48 AND B6(I) <= 57 THEN
                COMPUTE B6(I) = B6(I) + 4
            ELSE IF B6(I) >= 65 AND B6(I) <= 90 THEN
                COMPUTE B6(I) = B6(I) - 65
            ELSE IF B6(I) >= 97 AND B6(I) <= 122 THEN
                COMPUTE B6(I) = B6(I) - 71
            ELSE IF B6(I) = 43 THEN
                COMPUTE B6(I) = 62
            ELSE IF B6(I) = 47 THEN
                COMPUTE B6(I) = 63
            ELSE IF B6(I) = 61 THEN
                COMPUTE B6(I) = 0
                ADD 1 TO EQ
            END-IF
            END-IF
            END-IF
            END-IF
            END-IF
            END-IF
        END-PERFORM
        COMPUTE B8(1) = B6(1) * 4 + B6(2) / 16
        COMPUTE B8(2) = FUNCTION MOD(B6(2), 16) * 16 + B6(3) / 4
        COMPUTE B8(3) = FUNCTION MOD(B6(3), 4) * 64 + B6(4)
        PERFORM VARYING I FROM 1 BY 1 UNTIL I > 3
            ADD 1 TO B8(I)
            MOVE FUNCTION CHAR(B8(I)) TO RES(L+I:1)
        END-PERFORM
        ADD 3 TO L GIVING L
    END-PERFORM
    SUBTRACT EQ FROM L
    EXIT PROGRAM.

OK ?

??