DCPU-16 address registers

Four 32-bit address registers, P0, P1, P2, P3

All extra instructions use the mask: ........fff1100f

------------------- Load/store offset by small constant

SETB R, [Px+n] : load 8-bit zero extend
             1100
rrra annn 000    0
Register r = [Address register a + n] zero extended

SETS R, [Px+n] : load 8-bit sign extend
             1100
rrra annn 000    1
Register r = [Address register a + n] sign extended

SET R, [Px+n] : load 16-bit
             1100
rrra annn 001    0
Register r = [Address register a + n*2]

SETB [Px+n], R : store 8-bit
SETS [Px+n], R : store 8-bit
             1100
rrra annn 001    1
[Address register a + n] = Register r

SET [Px+n], R : store 16-bit
             1100
rrra annn 010    0
[Address register a + n*2] = Register r

------------------- Load/store offset by register

SETB R, [Px+r] : load 8-bit zero extend
             1100
rrra aRRR 010    1
Register r = [Address register a + Register R] zero extended

SETS R, [Px+r] : load 8-bit sign extend
             1100
rrra aRRR 011    0
Register r = [Address register a + Register R] sign extended

SET R, [Px+r] : load 16-bit
             1100
rrra aRRR 011    1
Register r = [Address register a + Register R]

SETB [Px+r], R : store 8-bit
SETS [Px+r], R : store 8-bit
             1100
rrra aRRR 100    0
[Address register a + Register R] = Register r

SET [Px+r], R : store 16-bit
             1100
rrra aRRR 100    1
[Address register a + Register R] = Register r

-------------------

ADD Px, n : Add small constant to address register
SUB Px, n : Subtract small constant from address register
             1100
aann nnnn 101    0
Address register a += sign extended N

B

C

D

E

-------------------

SET PxL, R : Load low half of address register with register
             1100
000a aRRR 111    1

SET PxH, R: Load high half of address register with register
             1100
001a aRRR 111    1

ADD Px, R : Add register to address register
             1100
010a aRRR 111    1

SUB Px, R : Subtract register from address register
             1100
011a aRRR 111    1

             1100
100a aRRR 111    1

             1100
101a aRRR 111    1

             1100
110a aRRR 111    1

------------------- No-operand address register operations

SET PUSH, Px : Push address register
111          1100
   a a000 111    1
Pushes an address register to the stack


SET Px, POP : Pop address register
111          1100
   a a001 111    1
Pops an address register from the stack

SET Px, constant : Load a 32-bit constant
111          1100
   a a010 111    1 nnnnnnnn nnnnnnnn nnnnnnnn nnnnnnnn
Px = a constant

SET Px, [word] : Load address register from memory
111          1100
   a a011 111    1 nnnnnnnn nnnnnnnn
Px = [word]

SET [word], Px : Store address register to memory
111          1100
   a a100 111    1 nnnnnnnn nnnnnnnn
[word] = Px

111          1100
   a a101 111    1

111          1100
   a a110 111    1

111          1100
   a a111 111    1