Description
This atom-editor-package, contains a grammar for the assembly language of the Visual-X-TOY-CPU. The grammar is used to provide a syntax-highlighting, in order to improve the overview and correctness, while programming in assembly language, for Visual-X-TOY.
Supported TOY instructions
| # | Assembly | Register-Transfer | C-Language |
|---|---|---|---|
| 0 | HLT | halt | |
| 1 | ADD Rd Rs Rt | Rd ← Rs + Rt | Rd = Rs + Rt |
| 2 | SUB Rd Rs Rt | Rd ← Rs - Rt | Rd = Rs - Rt |
| 3 | AND Rd Rs Rt | Rd ← Rs & Rt | Rd = Rs & Rt |
| 4 | XOR Rd Rs Rt | Rd ← Rs ^ Rt | Rd = Rs ^ Rt |
| 5 | SHL Rd Rs Rt | Rd ← Rs << Rt | Rd = Rs << Rt |
| 6 | SHR Rd Rs Rt | Rd ← Rs >> Rt | Rd = Rs >> Rt |
| 7 | LDA Rd imm | Rd ← imm | Rd = imm |
| 8 | LD Rd addr | Rd ← mem[addr] | Rd = a |
| 9 | ST Rd addr | mem[addr] ← Rd | a = Rd |
| A | LDI Rd Rt | Rd ← mem[Rt] | Rd = *Rt |
| B | STI Rd Rt | mem[Rt] ← Rd | *Rt = Rd |
| C | BZ Rd addr | if(RD==0) IP ← addr | if(RD==0) goto addr |
| D | BP Rd addr | if(RD>0) IP ← addr | if(RD>0) goto addr |
| E | JR Rd | IP ← addr | returning from a function |
| F | JL Rd addr | Rd ← IP; IP ← Rd | calling a function |
Modified HLT: Extended Instruction Set
Note that the stack in TOY grows with decreasing addresses and shrinks with
encreasing addresses.
Register-Transfer-Statements:
| Instruction | RT-Statements | Explanation |
|---|---|---|
| CALL ADDR; | RF ← RF - 1; | Increase stack size. |
| mem[RF] ← ADDR; | Safe return-address on stack. | |
| PC ← ADDR; | PC loads subroutine address. | |
| RET; | PC ← RE; | PC loads callee-return-address. |
| RF ← RF + 1; | Decrease stack size. | |
| PUSH Rd; | RF ← RF - 1; | Increase stack size. |
| mem[RF] ← Rd; | Safe value of Rd on stack. | |
| POP Rd; | Rd ← mem[RF]; | Safe value from stack on Rd. |
| RF ← RF + 1; | Decrease stack size. |
