.        Definition

10   RDBUFF    MACRO     &BUFADR,&RECLTH,&INDEV
15   .
20   .   MACRO TO READ RECORD INTO BUFFER
25   .
30             CLEAR     X              CLEAR LOOP COUNTER
35             CLEAR     A
40             CLEAR     S      
45             +LDT      #4096          SET MAXIMUM RECORD LENGTH
50   $LOOP     RDCHAR    &INDEV         TEST INPUT DEVICE
65             COMPR     A,S            END TEST FOR OF RECORD 
70             JEQ       $EXIT          EXIT LOOP IF EOR
75             STCH      &BUFADR,X      STORE CHARACTER IN BUFFER
80             TIXR      T              LOOP UNLESS MAXIMUM LENGTH
85             JLT       $LOOP          HAS BEEN REACHED
90   $EXIT     STX       &RECLTH        SAVE RECORD LENGTH
95             MEND 

                    (a)


     .        Definition

 5   RDCHAR    MACRO     &IN
10   .
15   .         MACRO TO READ CHARACTER INTO REGISTER A
20   .  
25             TD        =X'&IN'       TEST INPUT DEVICE
30             JEQ       *-3           LOOP UNTIL READY
35             RD        =X'&IN'       READ CHARACTER
40             MEND

                    (b)



     .     Invocation
               RDBUFF    BUFFER,LENGTH,F1

                      (c)


        Figure 4.11  Example of nested macro invocation.