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;;                                                                          ;;
;; This file is part of 'M', a MIPS system emulator.                        ;;
;;                                                                          ;;
;; (C) 2019 Stanislav Datskovskiy ( www.loper-os.org )                      ;;
;; http://wot.deedbot.org/17215D118B7239507FAFED98B98228A001ABFFC7.html     ;;
;;                                                                          ;;
;; You do not have, nor can you ever acquire the right to use, copy or      ;;
;; distribute this software ; Should you use this software for any purpose, ;;
;; or copy and distribute it to anyone or in any manner, you are breaking   ;;
;; the laws of whatever soi-disant jurisdiction, and you promise to         ;;
;; continue doing so for the indefinite future. In any case, please         ;;
;; always : read and understand any software ; verify any PGP signatures    ;;
;; that you use - for any purpose.                                          ;;
;;                                                                          ;;
;; See also http://trilema.com/2015/a-new-software-licensing-paradigm .     ;;
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;; Real-Time Clock Device ;;
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;-----------------------------------------------------------------------------
;; Real-Time Clock MMIO:
DECLARE_BUS_DEVICE RTC, 0x430, 0x434
;-----------------------------------------------------------------------------

;-----------------------------------------------------------------------------
; Epoch Time: 'Sec. since 00:00:00 Thursday, 1 January 1970'
%define RTC_REG_EPOCH_LO     0            ; Lower 32 bits of RTC Epoch Time
%define RTC_REG_EPOCH_HI     4            ; Upper 32 bits of RTC Epoch Time
;-----------------------------------------------------------------------------

;-----------------------------------------------------------------------------
_PD_Read_Word_RTC:                        ; Word reads from RTC:
        sub     eax, RTC_BASE             ; Adjust for base of RTC MMIO
        cmp     eax, RTC_REG_EPOCH_LO     ; Word at 0x0: Low 32 bits of time
        je      .rtc_epoch_low_word
        cmp     eax, RTC_REG_EPOCH_HI     ; Word at 0x4: High 32 bits of time
        je      .rtc_epoch_high_word
.rtc_undefined_reg:                       ; If unknown reg (how?) :
        ACHTUNG "Read Unknown RTC Reg?"
        xor     eax, eax                  ; ... return 0 always.
        ret                               ; Fin.
.rtc_epoch_low_word: ; Get LOW 32 bits of Epoch Time :
        call    _Get_Epoch_Time           ; Retrieve epoch time from host
        mov     eax, edx                  ; eax := low word
        ret                               ; Fin.
.rtc_epoch_high_word: ; Get HIGH 32 bits of Epoch Time :
        call    _Get_Epoch_Time           ; Retrieve epoch time from host
        shr     rdx, 32                   ; get high word
        mov     eax, edx                  ; eax := high word
        ret                               ; Fin.
;-----------------------------------------------------------------------------
_PD_Write_Word_RTC:                       ; Word writes to RTC do nothing!
        ret
;-----------------------------------------------------------------------------
_PD_Read_Byte_RTC:
        xor     eax, eax                  ; Read Byte from RTC: always 0
        ret
;-----------------------------------------------------------------------------
_PD_Write_Byte_RTC:
        ret                               ; Fin.
;-----------------------------------------------------------------------------
_Device_Init_RTC:                         ; Needs no init.
        ret
;-----------------------------------------------------------------------------
_Device_Shutdown_RTC:                     ; Needs no shutdown.
        ret
;-----------------------------------------------------------------------------