Retro1.org codex

*DECK NS$CVH
USETEXT CYB$NS
      PROC NS$CVH(INW,OUTW,ERR);       # CONVERT HEX DC TO BINARY      #
# TITLE NS$CVH - CONVERT HEX DISPLAY CODE TO BINARY.                   #
 
      BEGIN    # NS$CVH # 
# 
**    NS$CVH - CONVERT HEX TO BINARY. 
* 
*     J.C. LEE    1981
* 
*     THIS IS A UTILITY ROUTINE.  ITS FUNCTION IS TO CONVERT HEX TO 
*     BINARY. 
* 
*     PROC NS$CVH(INW, OUTW, ERR) 
* 
*     ENTRY:  
*       INW - INPUT WORD, LEFT-JUSTIFIED. 
* 
*     EXIT: 
*       OUTW - OUTPUT WORD, RIGHT-JUSTIFIED.
*       ERR  - SET IF ERROR IS FLAGED.
* 
*     METHOD: 
*       PROCESS A DISPLAY CODED CHARACTER AT A TIME UNTIL THE WHOLD 
*       WORD IS PROCESSED.  IF ERROR IS FOUND, FLAG IT. 
* 
# 
      DEF DC$0       #O"33"#;          # DISPLAY-CODED 0               #
      DEF DC$9       #O"44"#;          # DISPLAY-CODED 9               #
      DEF DC$A       #O"01"#;          # DISPLAY-CODED A               #
      DEF DC$F       #O"06"#;          # DISPLAY-CODED F               #
# 
      LOCAL VARIABLES 
# 
      ITEM INW        U;               # INPUT WORD, LEFT-JUSTIFIED    #
      ITEM OUTW       I;               # OUTPUT RIGHT-JUSTIFIED        #
      ITEM ERR        B;               # ERROR INDICATOR               #
      ITEM COMPLETE   B;               # CONVERSION DONE INDICATOR     #
      ITEM DIGIT      I;               # DISPLAY-CODED CHARACTER       #
      ITEM I          I;               # TEMPORARY VARIABLE            #
CONTROL EJECT;
      OUTW = 0; 
      ERR = FALSE;
      COMPLETE = FALSE;                # CONVERSION NOT DONE YET       #
 
      FOR I=0 STEP 1 WHILE I LS WC
                     AND NOT COMPLETE 
      DO
        BEGIN                          # PROCESS A DISPLAY-CODED CHAR  #
        DIGIT = C<I,1>INW;
        IF DIGIT GQ DC$A
          AND DIGIT LQ DC$F 
        THEN                           # DIGIT IS BETWEEN A AND F      #
          DIGIT = DIGIT + 9;           # CONVERT TO BINARY             #
        ELSE
          BEGIN 
          IF DIGIT GQ DC$0
            AND DIGIT LQ DC$9 
          THEN                         # DIGIT IS BETWEEN 0 AND 9      #
            DIGIT = DIGIT - O"33";     # CONVERT TO BINARY             #
          ELSE                         # DIGIT IS NOT A VALID HEX CHAR #
            BEGIN 
            COMPLETE = TRUE;
            IF DIGIT NQ 0 
            THEN                       # ERROR IF NOT END OF FIELD     #
              ERR = TRUE; 
            END 
          END 
        IF NOT COMPLETE 
        THEN
          OUTW = OUTW*16 + DIGIT;      # BINARY VALUE                  #
        END 
      RETURN; 
      END 
TERM