Subversion Repositories zipcpu

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;
; Filename:     wdt.S
;
; Project:      Zip CPU -- a small, lightweight, RISC CPU soft core
;
; Purpose:      Test to see whether or not the watchdog timer works.  We'll
;               start the watchdog, clear a register, then write as many times
;               as we can to memory before the watchdog kicks in.
;
; Creator:      Dan Gisselquist, Ph.D.
;               Gisselquist Technology, LLC
;
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;
; Copyright (C) 2015, Gisselquist Technology, LLC
;
; This program is free software (firmware): you can redistribute it and/or
; modify it under the terms of  the GNU General Public License as published
; by the Free Software Foundation, either version 3 of the License, or (at
; your option) any later version.
;
; This program is distributed in the hope that it will be useful, but WITHOUT
; ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or
; FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
; for more details.
;
; License:      GPL, v3, as defined and found on www.gnu.org,
;               http://www.gnu.org/licenses/gpl.html
;
;
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;
; Registers:
;       R12     Peripheral base
;       R11     Address of our one memory variable
;
#include "sys.i"
start:
        LDI     0xc0000000,R12  ; Get the address of our peripheral base
        MOV     $1(PC),R11      ; Get a memory address for a variable
        BRA     skip_test_variable
test_variable:
        .DAT    0
skip_test_variable:
        LDI     $-1,R0  ; Start the watchdog timer
        STO     R0,sys.bus.wdt(R12)
        LSR     $1,R0   ; R0 now = 0x7fffffff
        STO     R0,sys.bus.tma(R12)
        LSR     $1,R0   ; R0 now = 0x3fffffff
        STO     R0,sys.bus.tmb(R12)
        LSR     $1,R0
        STO     R0,sys.bus.tmc(R12)
        ;
        CLR     R0
wdt_test_loop:
        ADD     $1,R0
        LOD     (R11),R1
        CMP     R0,R1
        STO.LT  R0,(R11)
        TST     -1,R0
        BLT     wdt_test_program_is_broken
        BRA     wdt_test_loop

wdt_test_program_is_broken:
        HALT