;* ======================================================================== *;
;*  The routines and data in this file (el_event.mac) are dedicated to the  *;
;*  public domain via the Creative Commons CC0 v1.0 license by its author,  *;
;*  Joseph Zbiciak.                                                         *;
;*                                                                          *;
;*          https://creativecommons.org/publicdomain/zero/1.0/              *;
;* ======================================================================== *;

;; ======================================================================== ;;
;;  Emu-Link Support Macros:  Event API                                     ;;
;;                                                                          ;;
;;  The Event API was developed mainly to aid debugging jzIntv's SDL        ;;
;;  event engine at a low level.  It provides a mechanism to read copies    ;;
;;  of events out of jzIntv's event queue, either as event numbers or as    ;;
;;  strings representing the SDL event names.                               ;;
;;                                                                          ;;
;;  jzIntv keeps a queue of the last 64 events to arrive, to allow some     ;;
;;  amount of buffering between the code on the Intellivision and the       ;;
;;  emulator itself.  APIs below return the oldest event or indicate when   ;;
;;  the queue is empty.                                                     ;;
;;                                                                          ;;
;;  API SUMMARY                                                             ;;
;;                                                                          ;;
;;  Macro:              Returns:                                            ;;
;;  ELEV_GET_NUM        Get event by number into R0.                        ;;
;;  ELEV_GET_NAME       Get event by name into buffer in RAM.               ;;
;;                                                                          ;;
;;  For ELEV_GET_NAME, the buffer address can be passed as a constant or    ;;
;;  a register.  Slightly faster code results if the buffer address is      ;;
;;  in R2.  The event name returned by ELEV_GET_NAME is limited to 18       ;;
;;  characters plus a NUL byte (19 bytes total).                            ;;
;;                                                                          ;;
;;  OUTPUTS:                                                                ;;
;;      R0    $FFFF if no event, otherwise the event number                 ;;
;;      R1    0 = Key-up event, 1 = Key-down event                          ;;
;;      R2    Zeroed for GET_NUM;  Address of buffer for GET_NAME.          ;;
;;                                                                          ;;
;; ======================================================================== ;;

    IF (DEFINED _EMU_LINK_MAC) = 0
        ERR "You must include emu_link.mac before el_event.mac"
    ENDI

    IF ((DEFINED _EL_EVENT_MAC) = 0) AND ((DEFINED _EMU_LINK_MAC) <> 0)
_EL_EVENT_MAC   QEQU    1

MACRO       ELEV_GET_NUM
            CLRR        R2
            EL_CALL_SC  9
ENDM

MACRO   ELEV_GET_NAME buf
    IF _el_isreg(%buf%)
        IF EL_CPU_REGS.%buf% <> 2
            MOVR        %buf%,  R2
        ENDI
    ELSE
            MVII        #%buf%, R2
    ENDI
            EL_CALL_SC  9
ENDM

    ENDI