pif_tasks.v 21.2 KB
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task pif_test; // rac qsim testbed
    begin
       test_selected <= HIGH;
       repeat (10) @(posedge clock);

        config_rdram;

 	 repeat (10) @(posedge clock);


       $finish;
       end
endtask

task pif_interrupt;
// test interrupt generation and clearing logic
    begin
       test_selected <= HIGH;
       repeat (10) @(posedge clock);

        config_rdram;

       // 64 byte transfer pif to dram
       write_word(BUS_ADDRESS_SI_DRAM_ADDRESS, 3, BUS_ADDRESS_DRAM);
       write_word(BUS_ADDRESS_SI_PIF_AD_RD64B, 3, 32'h1fc007c0);

        read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
        while (data[0] & 32'h0fff)  begin
		// wait for dma status to go to idle and read busy to clear
	    if (data[0] & 32'h1000 == 1)
		$display ("ERROR task pif_interrupt interrupt set during dma_busy");
		
            read_word(BUS_ADDRESS_SI_STATUS, 3); // get next status for while eval
        end
	// dma busy fell through, check for interrupt being set
	read_word(BUS_ADDRESS_SI_STATUS, 3);
	if (data[0] & 32'h1000 != 32'h1000)
		$display ("ERROR task pif_interrupt interrupt should be set");

	// now clear out the interrrupt 
	write_word(BUS_ADDRESS_SI_STATUS, 3, 0);

	read_word(BUS_ADDRESS_SI_STATUS, 3);
		if (data[0] & 32'h1000 == 32'h1000)
			$display ("ERROR task pif_interrupt interrupt should be cleared");





       $finish;
       end
endtask
task pif_rd_lap1;
// dma/ io overlap conflict test bed
    begin
       test_selected <= HIGH;
       repeat (10) @(posedge clock);

// set up a dma, try to line up an io_read with end of dma active

        config_rdram;

// io request during 2nd to last cycle of!dma_state !- idle
       // 64 byte transfer pif to dram
       write_word(BUS_ADDRESS_SI_DRAM_ADDRESS, 3, BUS_ADDRESS_DRAM);
       write_word(BUS_ADDRESS_SI_PIF_AD_RD64B, 3, 32'h1fc007c0);

        read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
        while ((data[0] & 32'h0f00) != 32'h300)  begin //  dma_state 3 is near end
            read_word(BUS_ADDRESS_SI_STATUS, 3); // get next status for while eval
        end
	// do overlapping read request
	// with no delays, 1 ck of dma_!idle after write
	// repeat (1) @(posedge clock); // write during last clock;
	read_word(32'h1fc007c0,3);


// now delay the io read request by 1 clock, during last clock of dmastate !idle
       // 64 byte transfer pif to dram
       write_word(BUS_ADDRESS_SI_DRAM_ADDRESS, 3, BUS_ADDRESS_DRAM);
       write_word(BUS_ADDRESS_SI_PIF_AD_RD64B, 3, 32'h1fc007c0);

        read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
        while ((data[0] & 32'h0f00) != 32'h300)  begin //  dma_state 3 is near end
            read_word(BUS_ADDRESS_SI_STATUS, 3); // get next status for while eval
        end
    // do overlapping read request
    // with no delays, 1 ck of dma_!idle after write
    repeat (1) @(posedge clock); // write during last clock;
    read_word(32'h1fc007c0,3);


// now delay the io read request by 2 clock, 1st clock of idle
       write_word(BUS_ADDRESS_SI_DRAM_ADDRESS, 3, BUS_ADDRESS_DRAM);
       write_word(BUS_ADDRESS_SI_PIF_AD_RD64B, 3, 32'h1fc007c0);

        read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
        while ((data[0] & 32'h0f00) != 32'h300)  begin //  dma_state 3 is near end
            read_word(BUS_ADDRESS_SI_STATUS, 3); // get next status for while eval
        end
    // do overlapping read request
    // with no delays, 1 ck of dma_!idle after write
    repeat (2) @(posedge clock); // write during 1st clock of idll
    read_word(32'h1fc007c0,3);



       $finish;
       end
endtask
task pif_rd_lap2;
// dma/ io overlap conflict test bed
    begin
       test_selected <= HIGH;
       repeat (10) @(posedge clock);

// set up a dma, try to line up an io_read with end of dma active

        config_rdram;

// io request during 2nd to last cycle of!dma_state !- idle
       // 64 byte transfer pif to dram
       write_word(BUS_ADDRESS_SI_DRAM_ADDRESS, 3, BUS_ADDRESS_DRAM);
       write_word(BUS_ADDRESS_SI_PIF_AD_RD64B, 3, 32'h1fc007c0);

        read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
        while ((data[0] & 32'h0f00) != 32'h300)  begin //  dma_state 3 is near end
            read_word(BUS_ADDRESS_SI_STATUS, 3); // get next status for while eval
        end
    // do overlapping read request
    // with no delays, 1 ck of dma_!idle after write
    repeat (1) @(posedge clock); // write during last clock;
    read_word(32'h1fc007c0,3);


       $finish;
       end
endtask
task pif_rd_lap3;
// dma/ io overlap conflict test bed
    begin
       test_selected <= HIGH;
       repeat (10) @(posedge clock);

// set up a dma, try to line up an io_read with end of dma active

        config_rdram;

// io request during 2nd to last cycle of!dma_state !- idle
       // 64 byte transfer pif to dram
       write_word(BUS_ADDRESS_SI_DRAM_ADDRESS, 3, BUS_ADDRESS_DRAM);
       write_word(BUS_ADDRESS_SI_PIF_AD_RD64B, 3, 32'h1fc007c0);

        read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
        while ((data[0] & 32'h0f00) != 32'h300)  begin //  dma_state 3 is near end
            read_word(BUS_ADDRESS_SI_STATUS, 3); // get next status for while eval
        end
// now delay the io read request by 2 clock, 1st clock of idle
    // do overlapping read request
    // with no delays, 1 ck of dma_!idle after write
    repeat (2) @(posedge clock); // write during 1st clock of idll
    read_word(32'h1fc007c0,3);



       $finish;
       end
endtask

task pif_rd64B;
    begin
       test_selected <= HIGH;
       repeat (10) @(posedge clock);

        config_rdram;

       // 64 bit transfer pif to dram
       write_word(BUS_ADDRESS_SI_DRAM_ADDRESS, 3, BUS_ADDRESS_DRAM);
       write_word(BUS_ADDRESS_SI_PIF_AD_RD64B, 3, 32'h1fc007c0);
      // repeat (800) @(posedge clock);

        read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
        while (data[0] & 32'hfff) begin
            read_word(BUS_ADDRESS_SI_STATUS, 3); // get next status for while eval
        end
    // dma status (data[0]) is done, so read data from dram
    // assumes pif is loaded with data = address
    read_word(BUS_ADDRESS_DRAM, 3);
        // read data is left shifted 2 bits from write address
       if (data[0] !== 32'h1f0)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+4, 3);
       if (data[0] !== 32'h1f1)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+8, 3);
       if (data[0] !== 32'h1f2)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+12, 3);
       if (data[0] !== 32'h1f3)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+16, 3);
       if (data[0] !== 32'h1f4)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+20, 3);
       if (data[0] !== 32'h1f5)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+24, 3);
       if (data[0] !== 32'h1f6)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+28, 3);
       if (data[0] !== 32'h1f7)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+32, 3);
       if (data[0] !== 32'h1f8)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+36, 3);
       if (data[0] !== 32'h1f9)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+40, 3);
       if (data[0] !== 32'h1fa)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+44, 3);
       if (data[0] !== 32'h1fb)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+48, 3);
       if (data[0] !== 32'h1fc)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+52, 3);
       if (data[0] !== 32'h1fd)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+56, 3);
       if (data[0] !== 32'h1fe)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+60, 3);
       if (data[0] !== 32'h1ff)
         $display ("ERROR task pif_read64B read data is %h  ",data[0]);


       $finish;
       end
    endtask

task pif_wr64B;
    begin
       test_selected <= HIGH;
       repeat (10) @(posedge clock);

        config_rdram;
        // load rdram
            write_word(BUS_ADDRESS_DRAM, 3,    32'h0ad00da0);
            write_word(BUS_ADDRESS_DRAM+4, 3,  32'h1ad11da1);
            write_word(BUS_ADDRESS_DRAM+8, 3,  32'h2ad22da2);
            write_word(BUS_ADDRESS_DRAM+12, 3, 32'h3ad33da3);
            write_word(BUS_ADDRESS_DRAM+16, 3, 32'h4ad00004);
            write_word(BUS_ADDRESS_DRAM+20, 3, 32'h5ad00005);
            write_word(BUS_ADDRESS_DRAM+24, 3, 32'h6ad00006);
            write_word(BUS_ADDRESS_DRAM+28, 3, 32'h7ad00007);
            write_word(BUS_ADDRESS_DRAM+32, 3, 32'h8ad00008);
            write_word(BUS_ADDRESS_DRAM+36, 3, 32'h9ad00009);
            write_word(BUS_ADDRESS_DRAM+40, 3, 32'haad0000a);
            write_word(BUS_ADDRESS_DRAM+44, 3, 32'hbad0000b);
            write_word(BUS_ADDRESS_DRAM+48, 3, 32'hcad0000c);
            write_word(BUS_ADDRESS_DRAM+52, 3, 32'hdad0000d);
            write_word(BUS_ADDRESS_DRAM+56, 3, 32'head0000e);
            write_word(BUS_ADDRESS_DRAM+60, 3, 32'hfadfffff);

       // 64 bit transfer dram to pif
       write_word(BUS_ADDRESS_SI_DRAM_ADDRESS, 3, BUS_ADDRESS_DRAM);
        // writing to pif word address 7f0
       write_word(BUS_ADDRESS_SI_PIF_AD_WR64B, 3, 32'h1fc007c0);

        read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
        while (data[0] & 32'hfff) begin
            read_word(BUS_ADDRESS_SI_STATUS, 3); // get next status for while eval
        end


       $finish;
       end
    endtask


task pif_wr_rd;
    begin
       test_selected <= HIGH;
             $display(`CLOCK_COUNT, " : timer function ");
       repeat (10) @(posedge clock);

        config_rdram;
        // load rdram
             write_word(BUS_ADDRESS_DRAM, 3,    32'h0ad00da0);
             write_word(BUS_ADDRESS_DRAM+4, 3,  32'h1ad11da1);
             write_word(BUS_ADDRESS_DRAM+8, 3,  32'h2ad22da2);
             write_word(BUS_ADDRESS_DRAM+12, 3, 32'h3ad33da3);
             write_word(BUS_ADDRESS_DRAM+16, 3, 32'h4ad44da4);
             write_word(BUS_ADDRESS_DRAM+20, 3, 32'h5ad55da5);
             write_word(BUS_ADDRESS_DRAM+24, 3, 32'h6ad66da6);
             write_word(BUS_ADDRESS_DRAM+28, 3, 32'h7ad77da7);
             write_word(BUS_ADDRESS_DRAM+32, 3, 32'h8ad88da8);
             write_word(BUS_ADDRESS_DRAM+36, 3, 32'h9ad99da9);
             write_word(BUS_ADDRESS_DRAM+40, 3, 32'haadaadaa);
             write_word(BUS_ADDRESS_DRAM+44, 3, 32'hbadbbdab);
             write_word(BUS_ADDRESS_DRAM+48, 3, 32'hcadccdac);
             write_word(BUS_ADDRESS_DRAM+52, 3, 32'hdaddddad);
             write_word(BUS_ADDRESS_DRAM+56, 3, 32'headeedae);
             write_word(BUS_ADDRESS_DRAM+60, 3, 32'hfadffdaf);

       // 64 bit transfer dram to pif
       write_word(BUS_ADDRESS_SI_DRAM_ADDRESS, 3, BUS_ADDRESS_DRAM);
        // write to pif word address 1f0
       write_word(BUS_ADDRESS_SI_PIF_AD_WR64B, 3, 32'h1fc007c0);

        read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
        while (data[0] & 32'hfff) begin
            read_word(BUS_ADDRESS_SI_STATUS, 3); 
        end
    // done with write, now do read of pif

       // read back from pif to dram
       write_word(BUS_ADDRESS_SI_DRAM_ADDRESS, 3, BUS_ADDRESS_DRAM);
       write_word(BUS_ADDRESS_SI_PIF_AD_RD64B, 3, 32'h1fc007c0);

        // monitor status
        read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
        while (data[0] & 32'hfff) begin
            read_word(BUS_ADDRESS_SI_STATUS, 3); 
        end

    // did it make it to dram?
     read_word(BUS_ADDRESS_DRAM, 3);
       if (data[0] !== 32'h0ad00da0)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+4, 3);
       if (data[0] !== 32'h1ad11da1)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+8, 3);
       if (data[0] !== 32'h2ad22da2)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+12, 3);
       if (data[0] !== 32'h3ad33da3)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+16, 3);
       if (data[0] !== 32'h4ad44da4)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+20, 3);
       if (data[0] !== 32'h5ad55da5)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+24, 3);
       if (data[0] !== 32'h6ad66da6)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+28, 3);
       if (data[0] !== 32'h7ad77da7)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+32, 3);
       if (data[0] !== 32'h8ad88da8)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+36, 3);
       if (data[0] !== 32'h9ad99da9)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+40, 3);
       if (data[0] !== 32'haadaadaa)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+44, 3);
       if (data[0] !== 32'hbadbbdab)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+48, 3);
       if (data[0] !== 32'hcadccdac)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+52, 3);
       if (data[0] !== 32'hdaddddad)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+56, 3);
       if (data[0] !== 32'headeedae)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);
     read_word(BUS_ADDRESS_DRAM+60, 3);
       if (data[0] !== 32'hfadffdaf)
         $display ("ERROR task pif_wr_rd read data is %h  ",data[0]);


             $display(`CLOCK_COUNT, " : timer function ");
       $finish;
       end
    endtask

task pif_wr4B;
    begin
       test_selected <= HIGH;
       repeat (10) @(posedge clock);

        config_rdram;
        // load rdram
            write_word(BUS_ADDRESS_DRAM, 3,    32'h0ad00da0);
            write_word(BUS_ADDRESS_DRAM+4, 3,  32'h1ad11da1);
            //write_word(BUS_ADDRESS_DRAM+8, 3,  32'h2ad22da2);
            //write_word(BUS_ADDRESS_DRAM+12, 3, 32'h3ad33da3);
            //write_word(BUS_ADDRESS_DRAM+16, 3, 32'h4ad00004);
            //write_word(BUS_ADDRESS_DRAM+20, 3, 32'h5ad00005);
            //write_word(BUS_ADDRESS_DRAM+24, 3, 32'h6ad00006);
            //write_word(BUS_ADDRESS_DRAM+28, 3, 32'h7ad00007);
            //write_word(BUS_ADDRESS_DRAM+32, 3, 32'h8ad00008);
            //write_word(BUS_ADDRESS_DRAM+36, 3, 32'h9ad00009);
            //write_word(BUS_ADDRESS_DRAM+40, 3, 32'haad0000a);
            //write_word(BUS_ADDRESS_DRAM+44, 3, 32'hbad0000b);
            //write_word(BUS_ADDRESS_DRAM+48, 3, 32'hcad0000c);
            //write_word(BUS_ADDRESS_DRAM+52, 3, 32'hdad0000d);
            //write_word(BUS_ADDRESS_DRAM+56, 3, 32'head0000e);
            //write_word(BUS_ADDRESS_DRAM+60, 3, 32'hfadfffff);

       // 4 Byte io write to pif
        // writing to pif word address 1f0
       write_word( 32'h1fc007c0, 3, 32'h0ad00da0);

        read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
        while (data[0] & 32'hfff) begin
            read_word(BUS_ADDRESS_SI_STATUS, 3); // get next status for while eval
        end

             // read back the pif data to insure it is correct
             read_word( 32'h1fc007c0, 3);
             if (data[0] !== 32'h0ad00da0)
                    $display ("\t ERROR task pif_wr4B read data is %h ",data[0]);



       $finish;
       end
    endtask

task pif_rd4Bcpu;
    begin
       test_selected <= HIGH;
       repeat (10) @(posedge clock);


       // 4 bit io read pif to cpu
       // cpu should stall on this request.
       // assumes loaded pif memory with content = address
       read_word( 32'h1fc00000, 3);
       if (data[0] !== 0)
        $display ("ERROR task pif_rd4Bcpu read data is %h  ",data[0]);
        
       read_word( 32'h1fc00004, 3);
       if (data[0] !== 32'h1)
        $display ("ERROR task pif_rd4Bcpu read data is %h  ",data[0]);

       read_word( 32'h1fc007bc, 3);
       if (data[0] !== 32'h1ef)
        $display ("ERROR task pif_rd4Bcpu read data is %h  ",data[0]);

       read_word( 32'h1fc007c0, 3);
       if (data[0] !== 32'h1f0)
        $display ("ERROR task pif_rd4Bcpu read data is %h  ",data[0]);

       read_word( 32'h1fc007fc, 3);
       if (data[0] !== 32'h1ff)
        $display ("ERROR task pif_rd4Bcpu read data is %h  ",data[0]);

       $finish;
       end
    endtask

task pif_io_read_conflict;
    // perform a dma transfer, while it is in progress
    // issue a read to the reset exception vector
    begin
       test_selected <= HIGH;
       repeat (10) @(posedge clock);

        config_rdram;
    
        // 64 bit transfer pif to dram
            write_word(BUS_ADDRESS_SI_DRAM_ADDRESS, 3, BUS_ADDRESS_DRAM);
            write_word(BUS_ADDRESS_SI_PIF_AD_RD64B, 3, 32'h1fc007c0);
        // wait a while
         p_valid <= LOW; // return p_valid to 0
         repeat (200) @(posedge clock);


       // read reset exception address
       read_word( 32'h1fc00000, 3);
       if (data[0] !== 0)
        $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    
    // confirm dma completed also
    // assumes pif is loaded with data = address
    read_word(BUS_ADDRESS_DRAM, 3);
        // read data is left shifted 2 bits from write address
       if (data[0] !== 32'h1f0)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+4, 3);
       if (data[0] !== 32'h1f1)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+8, 3);
       if (data[0] !== 32'h1f2)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+12, 3);
       if (data[0] !== 32'h1f3)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+16, 3);
       if (data[0] !== 32'h1f4)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+20, 3);
       if (data[0] !== 32'h1f5)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+24, 3);
       if (data[0] !== 32'h1f6)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+28, 3);
       if (data[0] !== 32'h1f7)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+32, 3);
       if (data[0] !== 32'h1f8)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+36, 3);
       if (data[0] !== 32'h1f9)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+40, 3);
       if (data[0] !== 32'h1fa)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+44, 3);
       if (data[0] !== 32'h1fb)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+48, 3);
       if (data[0] !== 32'h1fc)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+52, 3);
       if (data[0] !== 32'h1fd)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+56, 3);
       if (data[0] !== 32'h1fe)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);
    read_word(BUS_ADDRESS_DRAM+60, 3);
       if (data[0] !== 32'h1ff)
         $display ("ERROR task pif_io_read_conflict read data is %h  ",data[0]);


       $finish;
       end
    endtask

task nmi_test;
    begin
       test_selected <= HIGH;
       repeat (10) @(posedge clock);

        config_rdram;

	   // must be run with +enable_nmi
	   // first transfer deaddead to 1fc007c0
	   // then rd64B 1fc007c0
       write_word(32'h1fc007c0, 3,    32'hdeaddead);

        read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
        while (data[0] & 32'hfff) begin
            read_word(BUS_ADDRESS_SI_STATUS, 3); // get next status for while eval
        end
	   // pif is loaded, read the data to generate nmi

       read_word(32'h1fc007c0, 3);
       if  (data[0] != 32'hdeaddead)  begin
       $display ("ERROR pif not properly loaded for nmi generation");
	$finish;
       end
       // cause nmi to happen
       write_word(BUS_ADDRESS_SI_DRAM_ADDRESS, 3, BUS_ADDRESS_DRAM);
       write_word(BUS_ADDRESS_SI_PIF_AD_RD64B, 3, 32'h1fc007c0);

	read_word(BUS_ADDRESS_SI_STATUS, 3); // read status word
	while (data[0] & 32'hfff) begin
	    read_word(BUS_ADDRESS_SI_STATUS, 3); // get next status for
	    end


       $finish;
       end
    endtask