ovm - ARCHIVED - A stack based virtual machine to act as a target for other programming languages

Age	Commit message (Collapse)	Author
2024-04-14	Created custom functions to convert (h)words to and from bytecode format	Aryadev Chavali
	Instead of using endian.h that is not portable AND doesn't work with C++, I'll just write my own using a forced union based type punning trick. I've decided to use little endian for the format as well: it seems to be used by most desktop computers so it should make these functions faster to run for most CPUs.
2024-04-12	Fix problems with running programs due to mismatched endian	Aryadev Chavali
	Basically ensure we're converting to big endian when writing bytecode and converting from big endian when reading bytecode.
2024-04-12	Fixing build problems due to endian.h	Aryadev Chavali
	Have to define _DEFAULT_SOURCE before you can use the endian conversion functions. As most standard library headers use features.h, and _DEFAULT_SOURCE must be defined before features.h is included, we have to include base.h before other headers.
2024-04-09	Added some TODOs to lib/inst.c to enforce endian	Aryadev Chavali

2023-11-03	Defined a `program` structure	Aryadev Chavali
	Essentially a "program header", followed by a count, followed by instructions. Provides a stronger format for bytecode files and allows for better bounds checking on instructions.
2023-11-02	Introduced instructions to engage with a call stack	Aryadev Chavali
	Essentially you may "call" an absolute program address, which pushes the current address onto the call stack. CALL_STACK does the same thing but the absolute program address is taken from the data stack. RET pops an address off the call stack then jumps to that address.
2023-11-02	Removed instruction OP_JUMP_REGISTER	Aryadev Chavali
	Not necessary when you can just push the relevant word onto the stack then just do OP_JUMP_STACK.
2023-11-01	Added instructions for MALLOC_STACK and SUB	Aryadev Chavali
	MALLOC_STACK is a stack based version of MALLOC, SUB does subtraction.
2023-11-01	Added stack based versions of MSET and MGET	Aryadev Chavali
	Essentially they use the stack for their one and only operand. This allows user level control, in particular it allows for loops to work correctly while using these operands.
2023-11-01	Added instruction to get the size of some allocation	Aryadev Chavali
	This will allow for more library level code to be written. For example, say you wanted to write a generic byte level reversal algorithm for dynamically sized allocations. Getting the size of the allocation would be fundamental to this operation.
2023-11-01	Added instructions for allocating, setting, getting and deleting heap memory	Aryadev Chavali
	One may allocate any number of (bytes\|hwords\|words), set or get some index from allocated memory, and delete heap memory. The idea is that all the relevant datums will be on the stack, so no register usage. This means no instructions should use register space at all (other than POP, which I'm debating about currently). Register space is purely for users.
2023-11-01	Introduced a new mathematical operator MULT	Aryadev Chavali
	Thankfully multiplication, like addition, is the same under 2s complement as it is for unsigned numbers. So I just need to implement those versions to be fine.
2023-11-01	Changed inst bytecode methods for new register system	Aryadev Chavali
	As registers may be theoretically infinite in number, we should use the largest size possible when referring to them in bytecode (a word).
2023-11-01	Removed OP_EQ signed versions as they're useless	Aryadev Chavali
	A negative number under 2s complement can never be equal to its positive as the top bit must be on. If two numbers are equivalent bit-by-bit then they are equal for both signed and unsigned numbers.
2023-10-31	Moved inst module to lib	Aryadev Chavali
	As it has no dependencies on vm specifically, and it's more necessary for any vendors who wish to target the virtual machine, it makes more sense for inst to be a lib module rather than a vm module.