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diff --git a/awk/vm/README.md b/awk/vm/README.md new file mode 100644 index 0000000..e6bd7a1 --- /dev/null +++ b/awk/vm/README.md @@ -0,0 +1,48 @@ +# Simple Stack-Based Virtual Machine + +This is an implementation of a minimal stack-based virtual machine in AWK, inspired by Forth. The VM provides basic stack manipulation, arithmetic operations, register access, and memory operations. + +## Architecture + +The VM consists of: +- A data stack (100 elements) +- Main memory (1000 cells) +- Three registers: + - A: General purpose register + - B: Often used as memory pointer + - P: Program pointer, used for sequential memory operations + +## Instruction Set + +### Stack Operations +- `DROP` - Remove top item from stack +- `DUP` - Duplicate top stack item +- `OVER` - Copy second item to top of stack +- Numbers are automatically pushed onto the stack + +### Arithmetic Operations +- `+` - Add top two stack items (a b -- a+b) +- `AND` - Bitwise AND of top two items +- `XOR` - Bitwise XOR of top two items +- `NOT` - Bitwise NOT of top item +- `2*` - Multiply top item by 2 (shift left) +- `2/` - Divide top item by 2 (shift right) + +### Register Operations +- `A` - Push value of A register onto stack +- `A!` - Store top stack value into A register +- `B!` - Store top stack value into B register + +### Memory Operations +- `@` - Fetch from memory address on stack +- `!` - Store to memory address on stack +- `@+` - Fetch from memory at P, then increment P +- `!+` - Store to memory at P, then increment P +- `@B` - Fetch from memory address in B register +- `!B` - Store to memory address in B register +- `@P` - Fetch from memory address in P register +- `!P` - Store to memory address in P register + +### Utility +- `.` - NO-OP (does nothing) +- `BYE` - Exit program \ No newline at end of file |