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;
; Filename:     test.S
;
; Project:      Zip CPU -- a small, lightweight, RISC CPU soft core
;
; Purpose:      A disorganized test, just showing some initial operation of
;               the CPU.  As a disorganized test, it doesn't prove anything
;               beyond the generic operation of the CPU.
;
; Status:       As of August, 2015, this file assembles, builds, and passes
;               all of its tests in the Verilator simulator.
;
; Creator:      Dan Gisselquist, Ph.D.
;               Gisselquist Tecnology, LLC
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
; 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
;
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
        sys.bus         equ     0xc0000000
        sys.breaken     equ     0x080
        sys.step        equ     0x040
        sys.gie         equ     0x020
        sys.sleep       equ     0x010
        sys.ccv         equ     0x008
        sys.ccn         equ     0x004
        sys.ccc         equ     0x002
        sys.ccz         equ     0x001
        sys.bu.pic      equ     0x000
        sys.bus.wdt     equ     0x001
        sys.bus.cache   equ     0x002
        sys.bus.ctrpic  equ     0x003
        sys.bus.tma     equ     0x004
        sys.bus.tmb     equ     0x005
        sys.bus.tmc     equ     0x006
        sys.bus.jiffies equ     0x007
        sys.bus.mtask   equ     0x008
        sys.bus.mpstl   equ     0x009
        sys.bus.mastl   equ     0x00a
        sys.bus.mstl    equ     0x00b
        sys.bus.utask   equ     0x00c
        sys.bus.upstl   equ     0x00d
        sys.bus.uastl   equ     0x00e
        sys.bus.ustl    equ     0x00f
#define DO_TEST_ASSEMBLER
test:
#ifdef  DO_TEST_ASSEMBLER
; We start out by testing our assembler.  We give it some instructions, which
; are then manually checked  by disassembling/dumping the result and making
; certain they match.  This is not an automated test, but it is an important
; one.
        noop
        bra     continue_test_with_testable_instructions
        break
        wait
        busy
        rtu
continue_test_with_testable_instructions:
        ; Now, let's place the assembler into a known state
        clr     r0
        clr     r1
        clr     r2
        clr     r3
        clr     r4
        clr     r5
        clr     r6
        clr     r7
        clr     r9
        clr     r10
        clr     r11
        clr     r12
        clr     r13
        ; Don't clear the CC register
        ; Don't clear the SP register
        ; And repeat for the user registers
        mov     R0,uR0
        mov     R0,uR1
        mov     R0,uR2
        mov     R0,uR3
        mov     R0,uR4
        mov     R0,uR5
        mov     R0,uR6
        mov     R0,uR7
        mov     R0,uR8
        mov     R0,uR9
        mov     R0,uR10
        mov     R0,uR11
        mov     R0,uR12
        mov     R0,uR13
        mov     R0,uCC
        ; Don't clear the user PC register
        ; Now, let's try loading some constants into registers
dead_beef       equ     0xdeadbeef
        ldi     0x0dead,r5
        ldi     0x0beef,r6
        ldi     0xdeadbeef,r7
        ldihi   0xdead, r8
        ldilo   0xbeef, r8
        ldi     dead_beef,r9
        cmp     r5,r6
        bz      test_failure
        cmp     r7,r8
        bnz     test_failure
        ldi     $deadbeefh,r7   ; Try loading with the $[HEX]h mneumonic
        cmp     r7,r8
        bnz     test_failure
        cmp     r7,r9
        bnz     test_failure
        bra     skip_dead_beef
dead_beef.base:
        word    0
        fill    5,dead_beef
        word    0
dead_beef.zero          equ     0
dead_beef.values        equ     1
skip_dead_beef:
        lod     dead_beef.base(pc),r10  ; Should load a zero here
        cmp     r10,r11                 ; r11 should still be zero from init abv
        bnz     test_failure
        mov     dead_beef.base(pc),r10  ; Now, let's get the address
        lod     dead_beef.values(r10),r10       ; r10 now equals 0xdeadbeef
        cmp     r10,r9
        bnz     test_failure
        
; Test whether or not we can properly decode OCTAL values
        clr     r0      ; Re-clear our register set first
        clr     r1
        clr     r2
        clr     r3
        clr     r4
        clr     r5
        clr     r6
        clr     r7
        clr     r9
        clr     r10
        clr     r11
        clr     r12
        clr     r13
        ;
        ldi     $024o,r0
        ldi     $20,r1
        cmp     r0,r1
        bnz     test_failure
        ldi     $024,r0
        cmp     r0,r1
        bnz     test_failure
        clr     r0
        clr     r1
        mov     $1+r0,r2
        mov     $2+r0,r3
        mov     $22h+r0,r4
        mov     $377h+r0,ur5
        noop
        nop
        add     r2,r0
        add     $32,r0
        add     $-33,r0
        bnz     test_failure
        not.z   r0
        bge     test_failure
junk_address:
        clrf    r0
        bnz     test_failure
        ldi     $5,r1
        cmp     $0+r0,r1
        not.lt  r0
        not.ge  r1
        mov     junk_address(pc),r2     ; Test pc-relative addressing
        mov     junk_address(pc),r3
        cmp     r2,r3
        bnz     test_failure
        lod     junk_address(pc),r5     ; Test loads with pc-relative addressing
        lod     junk_address(pc),r6
        cmp     r5,r6
        bnz     test_failure
; Now, let's test whether or not our LSR and carry flags work
        ldi     -1,r0   ; First test: shifting all the way should yield zero
        lsr     32,r0
        cmp     0,r0
        bnz     test_failure
        ldi     -1,r0   ; Second test: anything greater than zero should set
        lsr     0,r0    ; the carry flag
        bc      test_failure
        lsr     1,r0
        tst     sys.ccc,cc
        bz      test_failure
        lsr     31,r0
        tst     sys.ccc,cc
        bz      test_failure
        lsr     1,r0
        bc      test_failure
; Now repeat the above tests, looking to see whether or not ASR works
        ldi     -1,r0
        asr     32,r0
        cmp     -1,r0
        bnz     test_failure
        ldi     -1,r0
        asr     0,r0
        bc      test_failure
        cmp     -1,r0
        bnz     test_failure
        asr     1,r0
        tst     sys.ccc,r14
        bz      test_failure
        asr     30,r0
        tst     sys.ccc,r14
        bz      test_failure
#endif

#ifdef  NOONE // Testing comments after ifdef
#else   ; After else
#endif /* and after endif */
testbench:
        // Let's build a software test bench.
        ldi     $c0000000h,r12  ; Set R12 to point to our peripheral address
        mov     r12,ur12
        mov     test_start(pc),upc
        ldi     0x8000ffff,r0   ; Clear interrupts, turn all vectors off
        sto     r0,(r12)
        rtu
        mov     ucc,r0
        tst     -256,r0
        bnz     test_failure
        halt
// Go into an infinite loop if the trap fails
// Permanent loop instruction -- a busy halt if you will
test_failure:
        busy

; Now for a series of tests.  If the test fails, call the trap
; interrupt with the test number that failed.  Upon completion,
; call the trap with #0.

; Test LDI to PC
; Some data registers
test_data:
        .dat    __here__+0x0100000+5
test_start:
        ldi     $0x0100,r11
        lod     test_data+pc,pc
        clr     r11
        noop
        cmp     $0,r11
        trap.z  r11
        add     $1,r0
        add     $1,r0

// Let's test whether overflow works
        ldi     $0x0200,r11
        ldi     $-1,r0
        lsr     $1,r0
        add     $1,r0
        bv      first_overflow_passes
        trap    r11
first_overflow_passes:
// Overflow set from subtraction
        ldi     $0x0300,r11
        ldi     $1,r0
        rol     $31,r0                  ; rol $31,r0
        sub     $1,r0
        bv      subtraction_overflow_passes
        trap    r11
subtraction_overflow_passes:
// Overflow set from LSR
        ldi     $0x0400,r11
        ldi     $1,r0
        rol     $31,r0                  ; rol $31,r0
        lsr     $1,r0
        bv      lsr_overflow_passes
        trap    r11
lsr_overflow_passes:
// Overflow set from LSL
        ldi     $0x0500,r11
        ldi     $1,r0
        rol     $30,r0
        lsl     $1,r0
        bv      lsl_overflow_passes
        trap    r11
lsl_overflow_passes:
// Overflow set from LSL, negative to positive
        ldi     $0x0600,r11
        ldi     $1,r0
        rol     $31,r0
        lsl     $1,r0
        bv      second_lsl_overflow_passes
        trap    r11
second_lsl_overflow_passes:
// Test carry
        ldi     $0x0700,r11
        ldi     $-1,r0
        add     $1,r0
        tst     $2,cc
        trap.z  r11
// and carry from subtraction
        ldi     $0x0800,r11
        sub     $1,r0
        tst     $2,cc
        trap.z  r11

// Let's try a loop: for i=0; i<5; i++)
//      We'll use R0=i, Immediates for 5
        ldi     $0x0800,r11
        clr     r0
for_loop:
        noop
        add     $1,r0
        cmp     $5,r0
        blt     for_loop
//
// Let's try a reverse loop.  Such loops are usually cheaper to
// implement, and this one is no different: 2 loop instructions 
// (minus setup instructions) vs 3 from before.
// R0 = 5; (from before)
// do {
// } while (R0 > 0);
        ldi     $0x0900,r11
bgt_loop:
        noop
        sub     $1,r0
        bgt     bgt_loop

// How about the same thing with a >= comparison?
// R1 = 5; // Need to do this explicitly
// do {
// } while(R1 >= 0);
        ldi     $20,r0
        ldi     $5,r1
bge_loop:
        noop
        sub     $1,r1
        bge     bge_loop

// Let's try the reverse loop again, only this time we'll store our
// loop variable in memory.
// R0 = 5; (from before)
// do {
// } while (R0 > 0);
        ldi     $0x0a00,r11
        bra     mem_loop_test
loop_var:
        .dat    0
mem_loop_test:
        mov     loop_var(pc),r1
        ldi     $5,r0
        clr     r2
        sto     r0,(r1)
mem_loop:
        add     $1,r2
        add     $14,r0
        lod     (r1),r0
        sub     $1,r0
        sto     r0,(r1)
        bgt     mem_loop
        cmp     $5,r2
        trap.ne r11

// Return success / Test the trap interrupt
        clr     r11
        trap    r11
        noop
        noop

        busy

// And, in case we miss a halt ...
        halt