*TITLEGTBYTE -- GET A BYTE                                              00010000
C***********************************************************************
C                 COPYRIGHT ATLANTIC RICHFIELD COMPANY 1991            *
C***********************************************************************
*A    AUTHOR       H. LAVALLET                                          00020000
*A    DESIGNER     H. LAVALLET                                          00030000
*A    LANGUAGE     ASSEMBLER                                            00040000
*A    SYSTEM       S/370                                                00040100
*A    WRITTEN      08/13/81                                             00050000
*     REVISED      MM/DD/YY                                             00060000
*A                                                                      00070000
*A                                                                      00080000
*A    CALL GTBYTE (IBYTE, IBUF, IBX)                                    00090000
*A                                                                      00090100
*A    IN/OUT  ARGUMENT  TYPE  DESCRIPTION                               00090200
*A                                                                      00090300
*A    OUT     IBYTE     I4    RETURNED INTEGER HALFWORD CONTAINING      00100000
*A                            SELECTED BYTE.                            00110000
*A    IN      IBUF      I4    INPUT BUFFER WHICH CONTAINS BYTE          00120000
*A    IN      IBX       I4    INPUT BYTE INDEX WHICH POINTS TO THE      00130000
*A                            DESIRED BYTE POSITION IN IBUF. 1 IS       00140000
*A                            THE FIRST BYTE IN IBUF.                   00150000
*A                                                                      00160000
*A                                                                      00170000
*A    THIS ROUTINE GETS ANY SELECTED BYTE AND RETURNS IT IN THE LOW     00180000
*A    ORDER 8 BITS OF AN INTEGER HALFWORD. THE HIGH ORDER BITS OF THE   00190000
*A    RETURNED VALUE ARE SET TO ZERO.                                   00200000
*A                                                                      00210000
*A    NOTE: ROUTINE IS DESIGNED TO GET INTO A HALFWORD ONLY....         00220000
*                                                                       00230000
*                                                                       00240000
GTBYTE   CSECT                                                          00250000
*                                                                       00260000
R1       EQU       1                                                    00270000
R2       EQU       2                                                    00280000
R3       EQU       3                                                    00290000
R4       EQU       4                                                    00300000
R10      EQU       10                                                   00310000
R12      EQU       12                                                   00320000
R13      EQU       13                                                   00330000
R14      EQU       14                                                   00340000
R15      EQU       15                                                   00350000
*                                                                       00360000
BASE     EQU       R10                                                  00370000
*                                                                       00380000
         STM       R14,R12,12(R13)                                      00390000
         BALR      BASE,0                                               00400000
         USING     *,BASE                                               00410000
*                                                                       00420000
         L         R2,0(R1)            GET ADDRESS OF IBYTE             00430000
*                                                                       00440000
         L         R3,8(R1)            GET INDEX INTO IBUF              00450000
         L         R3,0(R3)                                             00460000
         LA        R4,1                                                 00470000
         SR        R3,R4               DETERMINE ADDRESS OF WHERE TO    00480000
         A         R3,4(R1)            GET BYTE FROM                    00490000
*                                                                       00500000
         MVC       3(1,R2),0(R3)     NOW MOVE SELECTED BYTE             00510000
         MVC       0(3,R2),=X'000000' FILL HIGH ORDER BITS WITH 0       00520000
*                                                                       00530000
         LM        R2,R12,28(R13)                                       00540000
         BR        R14                                                  00550000
         LTORG                                                          00560000
         END                                                            00570000