Project 12: MemoryDiag test [v2.5]

[bupjae]

1. Between out[0] = 21 and out[0] = 50, allocated size of Array A is 20. However, checkOverlap on out[0] = 32 and out[0] = 42 tests Array A as if allocated size is 3.

        let out[0] = 20;
        let a = Memory.alloc(20);
        let out[3] = a;                     // RAM[17003] = block address

// ... more test code ...

        let out[0] = 32;
        do Main.checkOverlap(b, 3, a, 3);
        let out[0] = 33;

// ... more test code ...

        let out[0] = 42;
        do Main.checkOverlap(c, 500, a, 3);
        let out[0] = 43;

2. Some out[0] code is used more than once. (code 70, 71, 72)
Primary prupose of out[0] is to distinguish where the test is failed. Therefore I assumed that duplicated code is not intended.

        // Deallocate blocks 'b' and 'c'.

        let out[0] = 70;
        do Memory.deAlloc(c);

        let out[0] = 71;
        do Memory.deAlloc(b);
        let out[0] = 72;

        // Test that deallocated blocks are placed on the free list and can
        // be reused.

        let out[0] = 70;
        let a = Memory.alloc(8000);
        let out[7] = a;                     // RAM[17007] = block address

        let out[0] = 71;
        do Main.checkRange(a, 8000);

        let out[0] = 72;
        do Memory.deAlloc(a);

[WBahn]

I can't tell what the problem is or what your question is.

Could you provide more detail, please?

[dolomiti7]

I think you are right on the first point. This is referring to project/12/MemoryTest/MemoryDiag/Main.jack

The overlap checks should be done with a size of 20 for a:
...
do Main.checkOverlap(b, 3, a, 20);
...
do Main.checkOverlap(c, 500, a, 20);
...

I have attached a corrected version, maybe the nand2tetris team will include it into their repository:
Edit: see post below

Main.jack (project/12/MemoryTest/MemoryDiag/Main.jack)

Regarding the second point, it looks to me intentional.

The idea was apparently that out[0] (e.g. memory address [17000]) contains an error code depending on where the test fails. Though this has not been properly documented. If [17000]==100 at the end of the program, everything was alright. For every other value in [17000], you can look up in Main.jack at which point the test failed.

[dolomiti7]

Sorry, I misread your second point. I have corrected this now as well. The error codes while re-allocating free blocks are now in the range of 80 to 85.

Corrected file:
Main.jack
(project/12/MemoryTest/MemoryDiag/Main.jack)

[bupjae]

Thanks for looking this issue.

It would be good if the next version of toolkit includes this fix.
(Although I'm not sure when the last update of toolkit is...)

[bupjae]

One more point: it seems that "Broken Memory.jack fails (deAlloc() does not recycle memory blocks):" in "MemoryDiag/README.html" also should be changed to RAM[17000] = 83