IJVM
From Wikipedia, the free encyclopedia
IJVM is an assembly language created by Andrew Tanenbaum for his MIC-1 architecture. It is used to teach assembly basics in his book Structured Computer Organization.
IJVM is mostly a subset of the JVM assembly language that is used in the Java platform. It is simplified at a point that writing complex programs can become very hard (for example, no shift instructions are provided).
[edit] IJVM Instructions
| Mnemonic | Operands | Description |
|---|---|---|
| BIPUSH | byte | Push a byte onto stack |
| DUP | N/A | Copy top word on stack and push onto stack |
| ERR | N/A | Print an error message and halt the simulator |
| GOTO | label name | Unconditional jump |
| HALT | N/A | Halt the simulator |
| IADD | N/A | Pop two words from stack; push their sum |
| IAND | N/A | Pop two words from stack; push Boolean AND |
| IFEQ | label name | Pop word from stack and branch if it is zero |
| IFLT | label name | Pop word from stack and branch if it is less than zero |
| IF_ICMPEQ | label name | Pop two words from stack and branch if they are equal |
| IINC | variable name, byte | Add a constant value to a local variable |
| ILOAD | variable name | Push local variable onto stack |
| IN | N/A | Reads a character from the keyboard buffer and pushes it onto the stack. If no character is available, 0 is pushed |
| INVOKEVIRTUAL | method name | Invoke a method |
| IOR | N/A | Pop two words from stack; push Boolean OR |
| IRETURN | N/A | Return from method with integer value |
| ISTORE | variable name | Pop word from stack and store in local variable |
| ISUB | N/A | Pop two words from stack; push their difference |
| LDC_W | constant name | Push constant from constant pool onto stack |
| NOP | N/A | Do nothing |
| OUT | N/A | Pop word off stack and print it to standard out |
| POP | N/A | Delete word from top of stack |
| SWAP | N/A | Swap the two top words on the stack |
| WIDE | N/A | Prefix instruction; next instruction has a 16-bit index |
Operand descriptions
- byte: A numeric literal, in octal (032 - leading zero), decimal (26 - no leading digits), or hexadecimal (0x1A - leading zero-x) format. Character literals ('M - leading single quote) are also allowed. Compiled to a 1-byte constant.
- label name: The string name of a label. Compiled to a 2-byte offset
- variable name: The string name of a local variable. Compiled to a 1-byte value, indicating an offset into the local variable frame.
- method name: The string name of a method. When compiled, the address of the method is calculated and put into the constant pool. This operand is then replaced with the 2-byte index (in the constant pool) of the address.
- constant name: The string name of a constant. Compiled to a 2-byte index.
- N/A: This instruction takes no operands.
