Retro1.org codex

*DECK NS$GNW
USETEXT CYB$NS
USETEXT DEF$NS
USETEXT SMB$NS
 
PROC NS$GNW(FROMARRAY,(BUFHDRSIZE),(NPWINDEX),NPUWORD); # GET NPU WORD #
 
# TITLE NS$GNW - GET NPU WORD.         #
 
      BEGIN    # NS$GNW # 
# 
**    NS$GNW - GET NPU WORD.
* 
*     J.C. LEE    1981
* 
*     THIS ROUTINE GETS A 16-BIT NPU WORD.
* 
*     PROC NS$GNW(FROMARRAY,(BUFHDRSIZE),(NPUINDEX),NPUWORD)
* 
*     ENTRY:  
*       FROMARRAY  - ARRAY NPU WORD TO GET FROM.
*       BUFHDRSIZE - BUFFER HEADER SIZE IN 8-BIT BYTES. 
*       NPUINDEX   - NPU WORD INDEX AFTER BUFFER HEADER.
* 
*     EXIT: 
*       NPUWORD = 16-BIT NPU WORD.
* 
*     METHOD: 
*       THE 16-BIT NPU WORD IS EXTRACTED FROM THE "FROMARRAY".
* 
# 
 
      ARRAY FROMARRAY [0:0] S(1); 
        BEGIN 
        ITEM ARRAYWORD U(0,0,60); 
        END 
 
      ITEM BUFHDRSIZE U;     # BUFFER HEADER SIZE IN 8-BIT BYTES       #
      ITEM NPWINDEX   U;     # NPU WORD INDEX AFTER BUFFER HEADER      #
      ITEM NPUWORD    U;     # 16-BIT NPU WORD                         #
 
      $BEGIN
      XREF
        BEGIN 
        PROC NS$DBG;         # TRACE PROCEDURE CALLS                   #
        END 
      $END
 
      ITEM BITCOUNT   I;     # BIT COUNT                               #
      ITEM I          I;     # TEMPORARY                               #
      ITEM J          I;     # TEMPORARY                               #
      ITEM K          I;     # TEMPORARY                               #
CONTROL EJECT;
 
      $BEGIN
      NS$DBG("GNW");
      $END
 
      P<SMB> = LOC(FROMARRAY);         # FWA OF BUFFER                 #
      NPUWORD = 0;
      BITCOUNT = BUFHDRSIZE*ASCSIZE + NPWINDEX*NPWSIZE; 
      I = BITCOUNT / WL;               # WORD INDEX                    #
      J = BITCOUNT - I*WL;             # FIRST BIT POSITION OF NPU WORD#
      K = J + NPWSIZE - WL;            # BITS IN NEXT CM WORD          #
 
      IF K GR 0 
      THEN                             # NPU WORD CROSSES CM WORD      #
        BEGIN 
        B<WL-NPWSIZE,NPWSIZE-K>NPUWORD = B<J,WL-J>SMBWORD[I]; 
        B<WL-K,K>NPUWORD = B<0,K>SMBWORD[I+1];
        END 
 
      ELSE                             # WHOLE NPU WORD FITS IN CM WORD#
        NPUWORD = B<J,NPWSIZE>SMBWORD[I]; 
 
      RETURN; 
      END   # NS$GNW #
      TERM