A toy cpu for learning basic cpu architecture. This repository contains assembler, emulator and sample assembly code.
cmake .
make
# assemble sum.s to sum binary
./assembler/assembler ./sample/sum.s ./sample/sum.bin
# emulate cpu with sum program
./emulator/emulator ./sample/sum.bin
| CPU bit | 16bit |
| number of registers | 8 |
| name of psw register | r5 |
| name of stack pointer register | r6 |
| name of program counter register | r7 |
| code | description |
|---|---|
| mov r0, r1 | copy register value (r0 = r1) |
| add r0, r1 | addition register value (r0 = r0 + r1) |
| sub r0, r1 | substruction register value (r0 = r0 - r1) |
| and r0, r1 | and logical operation (r0 = r0 & r1) |
| or r0, r1 | or logical operation (`r0 = r0 |
| sl r0 | 1bit shift operation (r0 = r0 << 1) |
| sr r0 | 1bit right operation (r0 = r0 >> 1) |
| ldl r0, 0x01 | set immediate value to lower 8bit in register |
| ldh r0, 0x01 | set immediate value to higher 8bit in register |
| cmp r0, r1 | substruction register value with changing PSW (r1 - r2) |
| je 0x01 | jump to address (0x01) when zero flag is up in psw |
| jmp 0x01 | jump to address (0x01) always |
| ld r0, 0x01 | load memory in 0x01 address to r0 register |
| st r0, 0x01 | store memory in 0x01 address from r0 register |
| hlt | stop cpu |
instruction using double register
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
- inst source dest ----
instruction using register and 8bit data
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
- inst source data
instruction using single register
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
- inst reg -----
instruction using single data
instruction using single data
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
- inst data -----
[FETCH_INST_0] → [FETCH_INST_1] → [FETCH_OPERAND_0] → [FETCH_OPERAND_1]
↑ ↓ (withou ld, st) ↓ (ld, st)
[WRITE_BACK] ← [ EXEC_INST ]