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# Time off work

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Got today and tomorrow off work, which with the bank holiday on Monday means five days straight. First proper break I've had since last New Year and last I'll probably have till Christmas so trying to make the most of it. My girlfriend's at work today and tomorrow so I've got a couple of free days to catch up on some coding.

I'm writing my text adventure scripting language again. I've been through this project about five times already in the past so am flying along at the moment. I've got global variables and arrays working and function calls without parameters yet.

Inside functions, global variable assignments, maths and printing operations are now working, as well as return statements.

Arbitrarily complex math expressions are also now up and running - both compile time and run time and the virtual machine is being developed in parrellel with the compiler.

Now need to go and get array values working inside functions then look at function parameters (by value and by reference) and local variables.

[LATER] Reference and value function parameters now working, as well as function overloading. Local variables up and running as well. Forgot to support const for everything at the start and was a bit of a pain going back over and implementing it as an afterthought but I guess that is just poor planning for you.

For consitency, it supports const returns from functions and const reference parameters but these are the most pointless features in a programming language ever since functions can only return by value and, since every variable is four bytes large, there is no real difference between a const reference parameter and a const by-value parameter.

Arrays can only be globals in this language. I'm going to implement static local variables next and I'm pretty sure it will be effortless to have local static arrays since the compiler is just going to pass back control to the routines that parse declaring global variables, but rely on the fact that the symbol table stack is in the function scope to keep the static variable scope local.

It is generating rather bloated byte-code for accessing array values since it is using the math stack to calculate the addresses so I might add some array specific instructions to the vm to pare this down a bit.

However, the following program:

x(int &a){    a=a-10;}int b[3]={ 20,30,40 };main(){    out b[1],end;    x(b[1]);    out b[1],end;}

produces the following output from the dissassembler

ds: 135ts: 147ss: 148program:   0:    setax 40   5:    call    6:    mpop   7:    end     8:    peek 0  13:    movar  14:    get  15:    mpush  16:    setrx 10  21:    mpush  22:    sub  23:    peek 0  28:    movar  29:    mpop  30:    put  31:    mpush  32:    mpop  33:    setrx 0  38:    mpush  39:    ret    40:    setrx 1  45:    mpush  46:    setrx 4  51:    mpush  52:    mul  53:    setrx 0  58:    mpush  59:    add  60:    mpop  61:    movar  62:    get  63:    mpush  64:    mpop  65:    outn  66:    outnl  67:    setrx 1  72:    mpush  73:    setrx 4  78:    mpush  79:    mul  80:    setrx 0  85:    mpush  86:    add  87:    mpop  88:    push  89:    setax 8  94:    call   95:    popn 4 100:    mpop 101:    setrx 1 106:    mpush 107:    setrx 4 112:    mpush 113:    mul 114:    setrx 0 119:    mpush 120:    add 121:    mpop 122:    movar 123:    get 124:    mpush 125:    mpop 126:    outn 127:    outnl 128:    setrx 0 133:    mpush 134:    ret  data:   0: 20   4: 30   8: 40text:   0: ""

and the expected output when run with the vm. Not exactly an optimising compiler, but I don't care.

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