; This simple program defines custom instructions.
; QUICK NOTE: Defining an already existing instruction as a custom instruction will overwrite it.
; Another thing is that trying to use a custom instruction before it is defined will not work.

custom! CINS 0x9999 reg int mem ; This custom instruction has opcode 0x9999, and it expects a register, an integer, and a memory address.
custom! CINS 0x9991 reg mem ; You can also define variants.
custom! CINS 0x9992 ; You can also do instructions without arguments.

LOAD r0, <CINS reg int mem> ; Load the opcode of instruction CINS into register 0. (This works on normal instructions too.)
LOAD r1, <CINS reg mem> ; Load the opcode of instruction CINS (other variant) into register 1.
LOAD r2, <CINS> ; I think you understand now.

ASSERT r0, 0x9999 ; Just asserting that the opcode in register 0 is correct.
ASSERT r1, 0x9991 ; Just asserting that the opcode in register 1 is correct.
ASSERT r2, 0x9992 ; You get the point.

CINS r1, 0x4F, &0x0078F2 ; Call our new CINS instruction!
CINS r15, &0xC0FFEE ; Calling the other variant as well.
CINS ; Calling the variant that has no arguments.

; Now, let's see what happens with pre-existing instructions:

CMP r0, r1 ; Old CMP instruction.

custom! CMP 0x8888 reg reg ; Overwriting CMP (reg, reg). (The other CMP instruction variants are left alone.)

CMP r0, r1 ; New CMP instruction.