20150420 - From Scratch Bug 2 : Source-Less Programming


This is a disruptive idea which comes back periodically: source-less programming. Is it possible to efficiently program at a level even lower than an assembler?

The general idea is that the editor is now something similar to an enhanced hex editor which edits a binary image directly. Lowest memory is split into three parts {{running image, annotations for edit image}, edit image}. The {running image, annotations for edit image} is the boot image. The {edit image} is working space which gets snapshot replacement for {running image} on a safe transition zone. The "annotation" section is what enables human understanding of the binary image.

Words
One way to keep the system very simple is to always work in 32-bit words. A 32-bit word in memory is one of four things {data, opcode, absolute address, rip relative address}. Data is easily handled by the hex editor part. The annotation could provide a name for the data or a comment. Opcodes in x86 can be complex but it is easy to simplify. Start with something similar to forth zero-operand and one-operand operations (calls, etc). Make all operations padded to 32-bit alignment (x86-64 can use the 2e ignored prefix to pad). A call for instance becomes {32-bit opcode for call, 32-bit rip relative branch address}. Or a global load becomes {32-bit opcode for load, 32-bit rip relative branch address}. Annotation memory can provide a name for the opcode. Annotation can provide a tag for each word in memory which marks if the memory is a relative or absolute address (word gets a different color based on tag similar to color forth). Addresses can be auto annotated by displaying the annotation associated with the destination. Editor works on the {edit image}, with insert and delete of words automatically adjusting all the words tagged as address (effectively relinking at edit time). The {edit image} can also keep a mapping of original {running image} address so that it is possible to view the live values of any data. Editor provides something to easily be able to write an annotation and have the associated opcode or address automatically get updated. For example type the opcode name and the 32-bit value is automatically updated. Very simple and yet powerful minimal tool.