tonytins/retro8
1
0
Fork 0
mirror of https://github.com/tonytins/retro8.git synced 2025-03-18 05:41:22 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

Implementated instructions 0x4000 to 0xC000

Browse source 
- Moved commonly used variables in runSystem() above the main match statement
This commit is contained in:
Tony Bark 2021-03-09 05:47:15 -05:00
parent c2f76c61a1
commit 3c4404f072
1 changed files with 97 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

103
scripts/Chip8.gd
View file

@ -77,6 +77,11 @@ func runSystem():
var jump = false
opcode = (memory[pc] << 8) | memory[pc + 1]
var vx = (opcode & 0x0F00) >> 8
var vy = (opcode & 0x00F0) >> 4
var address = opcode & 0x0FFF
var byte = (opcode & 0x00FF)
# Instructions
match (opcode & 0xF000):
@ -87,36 +92,122 @@ func runSystem():
gfx[i] = 0
isRedraw = true
0x00EE: # RET
sp -= 1
pc = stack[sp] + 2
jump = true
_:
var address = opcode & 0x0FFF
pc = address
jump = true
0x1000: # JP
var address = opcode & 0x0FFF
pc = address
jump = true
0x2000: # CALL
var address = opcode & 0x0FFF
stack[sp] = pc
sp += 1
pc = address
0x3000: # SNE Vx, byte
var vx = (opcode & 0x0F00) > 8
var byte = (opcode & 0x00FF)
if (registers[vx] != byte):
pc += 2
if (registers[vx] != byte):
pc += 2
0x4000: # SE Vx, byte
if (registers[vx] != byte):
pc += 2
0x5000: # SE Vx, Vy
if (registers[vx] != registers[vy]):
pc += 2
0x6000: # LD Vx, byte
registers[vx] = byte
0x7000: # ADD Vx, byte
registers[vx] = (registers[vx] + byte) & 0xFF
0x8000:
var result = registers[vx] - registers[vy]
match (opcode & 0x000F):
0x0000: # LD Vx, Vy
registers[vx] = registers[vy]
0x0001: # OR Vx, Vy
registers[vx] = (registers[vx] | registers[vy]) & 0xFF
0x0002: # AND Vx, Vy
registers[vx] = (registers[vx] | registers[vy]) & 0xFF
0x0003: # XOR Vx, Vy
registers[vx] = (registers[vx] ^ registers[vy]) & 0xFF
0x0004: # XOR Vx, Vy
if (result > 255):
registers[0xF] = 1
registers[vx] = result & 0xFF
0x0005: # SUB Vx, Vy
if (registers[vx] > registers[vy]):
registers[0xF] = 1
else:
registers[0xF] = 0
registers[vx] = result & 0xFF
0x0006: # SHR Vx {, Vy}
var shr_result = registers[vx] & 0x1
if (shr_result == 1):
registers[0xF] = 1
else:
registers[0xF] = 0
registers[vx] = registers[vx] >> 1
0x0007: # SUBN Vx, Vy
if (registers[vy] > registers[vx]):
registers[0xF] = 1
else:
registers[0xF] = 0
registers[vx] = result & 0xFF
0x000E: # SHL Vx {, Vy}
if (result == 1):
registers[0xF] = 1
else:
registers[0xF] = 0
registers[vx] = registers[vx] << 1
_:
print("Unsupported opcode at 0x8000: %X" ,opcode)
0x9000: # SNE Vx, Vy
if (registers[vx] != registers[vy]):
pc += 2
0xA000: # LD I, address
index = address
0xB000: # JP V0, address
pc = address + (registers[0x0] & 0xFF)
jump = true
0xC000: # RND Vx, byte
var rnd_result = (randi() % 256) & byte
registers[vx] = rnd_result
_:
print("Unsopported opcode: %X", opcode)