;from cpm22.asm from Jan 24 distribution extracted by Herb Johnson
; file dated Jan 7 2024, downloaded Jan 12 2024
; same as July 30 2023 READER ode fragment from cpm22.asm

; EXTENDED INSTRUCTIONS
;
CPROM   EQU     01EDH   ;COPY ROM
CMDSND  EQU     05DDH   ;SLAVE: SEND COMMAND
RECSEND	EQU	0AEDH   ;SLAVE: SET RECORD
RECRECV	EQU	0CEDH   ;SLAVE: GET RECORD
SHMRD   EQU     10DDH   ;SHARED MEM READ BYTE
SHMWR   EQU     11DDH   ;SHARED MEM WRITE BYTE
DMA     EQU     0FDDH   ;DMA


READER:	;READER CHARACTER INTO REGISTER A FROM READER DEVICE
        ;Z-FLAG SET IF NO DATA RECEIVED
        LXI     H, RXSIZE
        DCR     M               ;SIZE-1
        LXI     H, RXIDX
        JM      RXSER           ;BUFFER EMPTY, GET SERIAL
        MVI     D, (BUFF+100H)>>8
        MOV     E, M            ;E=INDEX
        LDAX    D               ;A=BYTE
        INR     M               ;INDEX+1 (CLEAR Z-FLAG)
        RET                     ;RETURN BYTE
RXSER:  MVI     M, 0            ;RESET RXIDX
        LXI     B, 0209H        ;SEQ 2, SERIAL RX
        DW      CMDSND          ;CALL KERNEL
        MOV     A, D            ;A=BUFFER SIZE
        STA     RXSIZE
        ORA     A               ;BUFFER EMPTY?
        RZ                      ;RETURN Z-FLAG SET
        LXI     D, BUFF+100H
        XRA     A
        DW      RECRECV         ;SHM->DE
        JMP     READER          ;RECALL READER

; following edited in to complete source code, don't use this like this!
:
RXSIZE:	DS	1		;RX SHM BUFF SIZE
RXIDX:	DS	1		;RX SHM BUFF INDEX

;BUFF	EQU	DIRBF+180h&0ff00h ;B:DRIVE/TX/RX BUFFER
BUFF	EQU	*		;arbitrary value should be at page boundary XX00H