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* 4830Kartik Agaram2018-12-031-1/+159
| | | | | | New helper: printing a byte in textual (hex) form. This required adding instructions for bitwise shift operations.
* 4748Kartik Agaram2018-11-181-4/+4
| | | | Fix CI.
* 4715 - support one more negation instructionKartik Agaram2018-10-231-0/+47
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* 4695Kartik Agaram2018-10-141-58/+58
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* 4694Kartik Agaram2018-10-131-43/+43
| | | | Check for duplicate docstrings.
* 4693Kartik Agaram2018-10-131-46/+43
| | | | | | | | Add the standard mnemonic for each opcode. We aren't ever going to have complete docs of the subset of the x86 ISA we support, so we need to help readers cross-correlate with the complete docs.
* 4692 - update online help for subxKartik Agaram2018-10-131-32/+32
| | | | | | It now includes details for 8-bit registers. And we'll just use the classic names for the registers so that the relationships between 8- and 32-bit versions are more obvious.
* 4688Kartik Agaram2018-10-121-35/+35
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* 4686Kartik Agaram2018-10-121-5/+5
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* 4634Kartik Agaram2018-10-011-5/+5
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* 4614 - redo simulated RAMKartik Agaram2018-09-291-1/+2
| | | | | | | | | | | Now simulated 'Memory' isn't just a single flat array. Instead it knows about segments and VMAs. The code segment will always be first, and the data/heap segment will always be second. The brk() syscall knows about the data segment. One nice side-effect is that I no longer need to mess with Memory initialization regardless of where I place my segments.
* 4503Kartik Agaram2018-09-221-3/+15
| | | | Include LEA (load effective address) in the SubX subset of x86 ISA.
* 4578 - subx: implement inc/dec operationsKartik Agaram2018-09-211-0/+121
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* 4547Kartik Agaram2018-09-161-1/+1
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* 4537Kartik Agaram2018-09-071-8/+48
| | | | | | | | | | | | | | | Streamline the factorial function; we don't need to save a stack variable into a register before operating on it. All instructions can take a stack variable directly. In the process we found two bugs: a) Opcode f7 was not implemented correctly. It was internally consistent but I'd never validated it against a natively running program. Turns out it encodes multiple instructions, not just 'not'. b) The way we look up imm32 operands was sometimes reading them before disp8/disp32 operands.
* 4527 - reading commandline argumentsKartik Agaram2018-08-301-7/+0
| | | | | | | | | | | The new example ex9 doesn't yet work natively. In the process I've emulated the kernel's role in providing args, implemented a couple of instructions acting on 8-bit operands (useful for ASCII string operations), and begun the start of the standard library (ascii_length is the same as strlen). At the level of SubX we're just only going to support ASCII.
* 4469Kartik Agaram2018-08-031-0/+425