Debugging Fill.asm "exptected expression"

[Vijay99]

Perhaps my code has some syntax error but I am not able to figure it out:
status line says: "expected expression at line 33"

(TURN)          // turns the screen black
@loo             // loo is a variable that counts the no of iterations
D=M             // line 33
D=D-8192
@LOOP
D;JGT           // go back to (LOOP) which checks for KBD input

Here's the file Fill.asm

[WBahn]

D-8192

Is not a recognized mnemonic.

There are 28 recognized mnemonics, all of which are defined in Figure 4.3.

Anything other than one of those 28 mnemonics is not guaranteed to work.

The author's assembler will accept D+M and M+D, though I would prefer it didn't as it reinforces the very confusion you are falling prey to.

[Vijay99]

I resolved it. Why was it giving the error at line 33, should it not refer to line 34?

WBahn wrote

The author's assembler will accept D+M and M+D, though I would prefer it didn't as it reinforces the very confusion you are falling prey to.

I take it to mean that D-8192 was confusing. Or is there some other confusion?
In totality, do you think it is a satisfactory solution to the problem?

[WBahn]

Vijay99 wrote

I resolved it. Why was it giving the error at line 33, should it not refer to line 34?

It may count lines starting with zero.

It may just return a line counter's current value and it doesn't increment until it moves onto the next line.

Several possible reasons. In general, whenever a tool says line N, it's a good idea to look at the lines immediately above and below if it isn't obvious that the problem is on the indicated line.

Vijay99 wrote

WBahn wrote

The author's assembler will accept D+M and M+D, though I would prefer it didn't as it reinforces the very confusion you are falling prey to.

I take it to mean that D-8192 was confusing. Or is there some other confusion?
In totality, do you think it is a satisfactory solution to the problem?

Do I think what is a satisfactory solution? What change did you make to solve the problem (of having an unknown expression in your code)?

D-8192 is NOT an instruction mnemonic.

The assembler has to convert each assembly instruction into exactly one 16-bit opcode. What opcode would it convert the instruction D=D-8192 into?

[Lozminda]

If I remember correctly (and it was a long time ago I did this, no doubt/hopefully I'll be corrected):

If one wants to take on number away from another, one has to load the first value into a register, and the other into the other register say D and A and then do something like M = D - A. My implementation is I'm sure wrong, but you get the Feeling, if you want to take values away from each other, everything's got to go into a register including the result...