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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.

;

;       Okay, as of 15 August, there are now some tests that don't pass.

;       In particular, the #include test used to pass but didn't pass today.

;       Likewise the PUSH() macro test hasn't passed yet.  Finally, be aware

;       that this implementation is specific to where it loads on a board.

;       I tried loading it on my Basys development board, where I had placed

;       RAM in a different location and ... things didn't work out so well.

;       So grep the __here__ line and adjust it for where you intend to load

;       this file.

;

;       In general, as I'm building the CPU, I'm modifying this file to place

;       more and more capability tests within the file.  If the Lord is

;       willing, this will become the proof that the CPU completely works.

;

;

; Creator:      Dan Gisselquist, Ph.D.

;               Gisselquist Technology, 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

;

;

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;

#include "sys.i"

        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.cctrap      equ     0x200

        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

#define LJMP_TEST

#define EARLY_BRANCH_TEST

#define BREAK_TEST

#define OVERFLOW_TEST

#define CARRY_TEST

#define LOOP_TEST

#define SHIFT_TEST

#define TRAP_TEST

;

; Since updating our multiplies, the old MPY_TEST doesn't work anymore.  It

; really needs to be rebuilt.  For now, we just disable it.  I know, this is the

; wrong approach.  Test first and don't get surprised later.  Yes.  I need to

; come back to this--hopefully before getting surprised.

;

; #define       MPY_TEST

#define PUSH_TEST

#define PIPELINE_STACK_TEST

#define MEM_PIPELINE_TEST

#define CONDITIONAL_EXECUTION_TEST

#define NOWAIT_PIPELINE_TEST    // Were wait states btwn regs removed properly?

#define BCMEM_TEST      // Do memory and conditions work well together?

#define PIPELINE_MEMORY_RACE_CONDITIONS

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

        break

        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     r8

        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

        ; Specifically, we're testing the LDI, LDIHI, and LDILO instructions

dead_beef       equ     0xdeadbeef

        ldi     0x0dead,r5

        ldi     0x0beef,r6

        ldi     0xdeadbeef,r7

        brev    0xb57b, 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 our operator precedence rules work

        ldi     5+3*8,r0

        ldi     3*8+5,r1

        cmp     r0,r1

        bnz     test_failure

        ldi     (5+3)*8,r0

        ldi     8*(3+5),r1

        cmp     r0,r1

        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     r8

        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     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

#endif

#ifdef  NOONE // Testing comments after ifdef

#else   ; After else

#endif /* and after endif */

#ifdef  LJMP_TEST

        // A long jump is a 32-bit instruction followed by a 32-bit address.

        // The CPU is supposed to jump to this address.  At issue in this test,

        // which can only really be verified by watching it in person currently,

        // is how fast this branch can take place.  Currently, it takes four

        // clocks--not that bad.

        //

        // Although really long jumps, we also test some of our early branching

        // forms here as well:

        //      1. Add to PC

        //      2. LOD (PC),PC (the long jump itself)

        //      3. LDI x,PC     // An early branch target not tested elsewhere

        //

        CLR     R0

        CLR     R1

        LJMP

        .dat    __here__+0x0100000+4

        ADD     1,R0

        ADD     1,R0

        ADD     1,R0

        ADD     1,R0

        ADD     1,R0

        ADD     1,R0

        CMP     3,R0

        BNZ     test_failure

        LOD.Z   __here__+2(PC),PC

        BRA     test_failure

        .dat    __here__+0x0100000+2

        ADD     1,R0

        ADD     1,R0

        ADD     1,R0

        CMP     5,R0

        BNZ     test_failure

// And our last early branching test

        LDI     0x0100000+__here__+4,PC

        ADD     1,R0

        ADD     1,R0

        ADD     1,R0

        SUB     1,R0

        CMP     4,R0

        BNZ     test_failure

#endif

#ifdef  EARLY_BRANCH_TEST

        // Unlike the previous test, this test is going to see whether or not

        // early branching messes with the pipeline.

        BRA     eb_a

        BUSY

eb_a:

        BRA     eb_b

        NOP

        BUSY

eb_b:

        BRA     eb_c

        NOP

        NOP

        BUSY

eb_c:

        BRA     eb_d

        NOP

        NOP

        NOP

        BUSY

eb_d:

        BRA     eb_e

        NOP

        NOP

        NOP

        NOP

        BUSY

eb_e:

        NOOP

        // Only problem is, I don't expect it to mess with the pipeline unless

        // the pipeline is full.  Therefore we are interested in something which

        // is not an early branch, conflicting with early branches.  So let's

        // try loading our pipeline in all kinds of different configurations,

        // just to see which if the conditional branch always annihilates the

        // early branch as desired.

        //

        CLR     R0

        BZ      ebz_a

        BUSY

ebz_a:

        BZ      ebz_b

        NOP

        BUSY

ebz_b:

        BZ      ebz_c

        NOP

        NOP

        BUSY

        // Let's repeat that last test, just in case the cache reloaded itself

        // in the middle and we didn't get our proper test.

ebz_c:

        BZ      ebz_d

        NOP

        NOP

        BUSY

ebz_d:

        BZ      ebz_e

        NOP

        NOP

        NOP

        BUSY

ebz_e:

        BZ      ebz_f

        NOP

        NOP

        NOP

        NOP

        BUSY

ebz_f:

        NOOP

#endif

#ifdef  BREAK_TEST

breaktest:

        bra     breaksupervisor

breakuser:

        clr     r0

        mov     1+r0,r1

        mov     1+r1,r2

        mov     1+r2,r3

        break           ; At address 0x0100097

        mov     1+r4,r5

        mov     1+r5,r6

        clr     cc

        busy

breaksupervisor:

        ldi     -1,r0

        mov     breakuser(pc),upc

        rtu     ; Should just keep returning immediately

        mov     upc,r0

        rtu

        rtu

        mov     upc,r1

        cmp     r0,r1

        bnz     test_failure

#endif

#ifdef  TRAP_TEST

traptest:

        bra     traptest_supervisor

        busy

traptest_user:

        trap    0

        busy

traptest_supervisor:

        mov     traptest_user(pc),upc

        rtu

        mov     ucc,r0

        tst     sys.cctrap,r0

        tst.nz  sys.gie,r0

        bz      test_failure

#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

        mov     stack(pc),usp

        ldi     0x8000ffff,r0   ; Clear interrupts, turn all vectors off

        sto     r0,(r12)

        rtu

        mov     ucc,r0

        and     0x0ffff,r0

        CMP     sys.cctrap+sys.gie,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     $0x01000,r11

        ldi     -1,r10

        lod     test_data+pc,pc

        clr     r10

        noop

        cmp     $0,r10

        trap.z  r11

        add     $1,r0

        add     $1,r0

#ifdef  OVERFLOW_TEST

// Let's test whether overflow works

        ldi     $0x02000,r11

        ldi     $-1,r0

        lsr     $1,r0

        add     $1,r0

        bv      first_overflow_passes

        trap    r11

first_overflow_passes:

// Overflow set from subtraction

        ldi     $0x03000,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     $0x04000,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     $0x05000,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     $0x06000,r11

        ldi     $1,r0

        rol     $31,r0

        lsl     $1,r0

        bv      second_lsl_overflow_passes

        trap    r11

#endif // OVERFLOW_TEST

#ifdef  CARRY_TEST

second_lsl_overflow_passes:

// Test carry

        ldi     $0x07000,r11

        ldi     $-1,r0

        add     $1,r0

        tst     sys.ccc,cc

        trap.z  r11

// and carry from subtraction

        ldi     $0x08000,r11

        clr     r0

        sub     $1,r0

        tst     sys.ccc,cc

        trap.z  r11

// Carry from right shift

        clr     r0              ; r0 = 0

        lsr     1,r0            ; r0 = 0, c = 0

        add.c   1,r0            ; r0 = 0

        cmp     1,r0            ; r0 ?= 1

        trap.z  r11

        LDI     1,r0            ; r0 = 1

        lsr     1,r0            ; r0 = 0, c = 1

        add.c   1,r0            ; r0 = 1

        cmp     1,r0

        trap.nz r11

        ldi     0x070eca6,r0

        ldi     0x0408b85,r1

        ldi     0x0387653,r2

        lsr     1,r0

        xor.c   r1,r0

        cmp     r2,r0

        trap.nz r11

#endif

#ifdef  LOOP_TEST

// Let's try a loop: for i=0; i<5; i++)

//      We'll use R0=i, Immediates for 5

        ldi     $0x09000,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     $0x0a000,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     $0x0b000,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

#endif

#ifdef  SHIFT_TEST

; Now, let's test whether or not our LSR and carry flags work

        ldi     $0x0c000,r11

        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

        ldi     -1,r0

        asr     1,r0

        cmp     -1,r0

        bnz     test_failure

// Let's test whether LSL works

        ldi     0x035,r2

        lsl     8,r2

        ldi     0x03500,r1

        cmp     r2,r1

        trap.ne r11

        ldi     0x074,r0

        and     0x0ff,r0

        or      r0,r2

        cmp     0x03574,r2

        trap.ne r11

#endif

#ifdef  MPY_TEST

// We have two multiply instructions.  Let's see if those work

        ldi     $0x0d000,r11    // Mark our test

        ldi     23171,r0        // = sqrt(2)/2 * 32768

        mpyu    r0,r0           // Should = 2/4 * 2^30 = 2^29 or thereabouts

        ldi     536895241,r2

        cmp     r0,r2

        trap.ne r11

        ldi     0x0ffff,r0

        mpyu    r0,r0

        ldi     0xfffe0001,r1

        cmp     r1,r0

        trap.ne r11

        ldi     0x08001,r0

        ldi     0x07fff,r1

        mpys    r0,r1           // FAILS: result is 0x008001 ??? (pipeline prob)

        ldi     0x3fff0001,r2

        neg     r2

        cmp     r2,r1           // @0x010011c

        trap.ne r11             //TRAP FAILS TO TRIGGER ????? (R2=0x0c000ffff,R1=0x0008001 -- did mpy even happen?)

        mpys    r0,r0           // FAILS: result is 0x40010001

        ldi     0x3fff0001,r2

        cmp     r2,r0

        trap.ne r11             // TRAP FAILS TO TRIGGER AGAIN

        ldi     0x08000,r0

        mpys    r0,r0           // R0 now equals 0x40000000

        ldi     0x40000000,r1

        cmp     r0,r1

        trap.ne r11

//

// And from our eyeball test ...

        LDI     0x01ff01ff,R0

        MOV     R0,R7

        MOV     8(SP),R6

        LSR     7,R0

        AND     7,R0

        LDI     7,R1

        SUB     R0,R1

        MOV     R1,R0

        MPYU    5,R0

        CMP     20,R0

        TRAP.NE R11

#endif

#ifdef  PUSH_TEST

        ldi     $0x0e000,r11    // Mark our test

        ldi     0x01248cab,r0

        ldi     0xd5312480,r1   // Let's see if we can preserve this as well

        mov     r1,r7

        FJSR(reverse_bit_order,R4);     // *SP = 0x010013d

        cmp     r0,r1

        trap.ne r11

        cmp     r0,r7

        trap.ne r11

#endif

#ifdef  PIPELINE_STACK_TEST

        ldi     $0x0f000,r11    // Mark our test

        LDI     1,R0

        MOV     1(R0),R1

        MOV     1(R1),R2

        MOV     1(R2),R3

        MOV     1(R3),R4

        MOV     1(R4),R5

        MOV     1(R5),R6

        FJSR(pipeline_stack_test,R7)

        CMP     1,R0

        trap.ne R11

        CMP     2,R1

        trap.ne R11

        CMP     3,R2

        trap.ne R11

        CMP     4,R3

        trap.ne R11

        CMP     5,R4

        trap.ne R11

        CMP     6,R5

        trap.ne R11

        CMP     7,R6

        trap.ne R11

#endif

#ifdef  MEM_PIPELINE_TEST

        LDI     0x10000,R11

        FJSR(mem_pipeline_test,R0)

#endif  // MEM_PIPELINE_TEST

#ifdef  CONDITIONAL_EXECUTION_TEST

        LDI     0x11000,R11

        FJSR(conditional_execution_test,R0)

#endif  // CONDITIONAL_EXECUTION_TEST

#ifdef  NOWAIT_PIPELINE_TEST

        LDI     0x12000,R11

        FJSR(nowait_pipeline_test,R0)

#endif  // NOWAIT_PIPELINE_TEST

#ifdef  BCMEM_TEST

        LDI     0x13000,R11

        CLR     R0

        LDI     -1,R1

        STO     R0,bcmemtestloc(PC)

        LOD     bcmemtestloc(PC),R1

        CMP     R0,R1

        TRAP.NZ R11

        CMP     0x13000,R11

        BZ      bcmemtest_cmploc_1

        STO     R11,bcmemtestloc(PC)

bcmemtest_cmploc_1:

        LOD     bcmemtestloc(PC),R0

        CMP     R0,R11

        TRAP.Z  R11

        CLR     R0

        CMP     R0,R11

        BZ      bcmemtest_cmploc_2

        STO.NZ  R11,bcmemtestloc(PC)

bcmemtest_cmploc_2:

        NOOP

        LOD     bcmemtestloc(PC),R0

        CMP     R0,R11

        TRAP.NZ R11

        BRA     end_bcmemtest

bcmemtestloc:

        WORD    0

end_bcmemtest:

#endif

#ifdef  PIPELINE_MEMORY_RACE_CONDITIONS

        LDI     0x14000,R11

        FJSR(pipeline_memory_race_test,R0)

#endif // PIPELINE_MEMORY_RACE_CONDITIONS

// Return success / Test the trap interrupt

        clr     r11

        trap    r11     // FAILS HERE FAILS FAILS FAILS !!!!!!!!!!!

        noop

        noop

        busy

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

        halt

// Now, let's test whether or not we can handle a subroutine

#ifdef  PUSH_TEST

reverse_bit_order:

        SUB     3,SP

        STO     R1,(SP)         ; R1 will be our loop counter

        STO     R2,1(SP)        ; R2 will be our accumulator and eventual result

        STO     R4,2(SP)

        LDI     32,R1

        CLR     R2

reverse_bit_order_loop:

        LSL     1,R2

        LSR     1,R0

        OR.C    1,R2

        SUB     1,R1

        BNZ     reverse_bit_order_loop

        MOV     R2,R0

        LOD     (SP),R1

        LOD     1(SP),R2

        LOD     2(SP),R4

        ADD     3,SP

        JMP     R4

#endif

; The pipeline stack test examines whether or not a series of memory commands

; can be evaluated right after the other without problems.  This depends upon

; the calling routine to properly set up registers to be tested.

;

; This is also an incomplete test, as nothing is done to test how these

; pipeline reads/writes are affected by condition codes.

;

#ifdef  PIPELINE_STACK_TEST

pipeline_stack_test:

        SUB     13,SP

        STO     R0,(SP)

        STO     R1,1(SP)

        STO     R2,2(SP)

        STO     R3,3(SP)

        STO     R4,4(SP)

        STO     R5,5(SP)

        STO     R6,6(SP)

        STO     R7,7(SP)

        STO     R8,8(SP)

        STO     R9,9(SP)

        STO     R10,10(SP)

        STO     R11,11(SP)

        STO     R12,12(SP)

        XOR     -1,R0

        XOR     -1,R1

        XOR     -1,R2

        XOR     -1,R3

        XOR     -1,R4

        XOR     -1,R5

        XOR     -1,R6

        XOR     -1,R7

        XOR     -1,R8

        XOR     -1,R9

        XOR     -1,R10

        XOR     -1,R11

        XOR     -1,R12

        LOD     (SP),R0

        LOD     1(SP),R1

        LOD     2(SP),R2

        LOD     3(SP),R3

        LOD     4(SP),R4

        LOD     5(SP),R5

        LOD     6(SP),R6

        LOD     7(SP),R7

        LOD     8(SP),R8

        LOD     9(SP),R9

        LOD     10(SP),R10

        LOD     11(SP),R11

        LOD     12(SP),R12

        ADD     13,SP

        JMP     R7

#endif // PIPELINE_STACK_TEST

#ifdef  MEM_PIPELINE_TEST

mem_pipeline_test:

        SUB     4,SP

        STO     R0,(SP)

        STO     R1,1(SP)

        LDI     0x10000,R11

        ;

        ; Test #1 ... Let's start by writing a value to memory

        LDI     -1,R0

        CLR     R1

        STO     R0,2(SP)

        LOD     2(SP),R1

        CMP     R1,R0

        MOV.NZ  R11,CC

        ; Test #2, reading and then writing a value from memory

        NOP

        NOP

        CLR     R0

        CLR     R1

        LOD     2(SP),R0        ; This should load back up our -1 value

        STO     R0,3(SP)

        ; Insist that the pipeline clear

        LOD     2(SP),R0

        ; Now let's try loading into R1

        NOP

        NOP

        NOP

        NOP

        LOD     3(SP),R1

        CMP     R1,R0

        MOV.NZ  R11,CC

        LOD     (SP),R0

        LOD     1(SP),R1

        ADD     4,SP

        JMP     R0

#endif

#ifdef  CONDITIONAL_EXECUTION_TEST

conditional_execution_test:

        SUB     1,SP

        STO     R0,(SP)

        ;

        CLRF    R0

        ADD.Z   1,R0

        TRAP.NZ R11

        CMP.Z   0,R0

        TRAP.Z  R11

        LOD     (SP),R0

        ADD     1,SP

        JMP     R0

#endif

;

; Pipeline stalls have been hideous problems for me.  The CPU has been modified

; with special logic to keep stages from stalling.  For the most part, this