does those opcodes exists?
I also suppose no one know....
they don't exist
if rl l or srl l exist why would not these undocumented opcode exist ?
like DD CB 3D ??
Because dd/fd+cb stuff results in:
opcode (x + displacement),reg
what is an opcode?
what is an opcode?
the numerical (often in hexadecimal) representation of an assembly instruction, without operands.
For example the LD A,10 on z80 has opcode $3E
the other byte, 10 (dec) is the operand.
Because dd/fd+cb stuff results in:
opcode (x + displacement),reg
It depends on the instructions.
for those starting with 00:
opcode (hl) results in: opcode (x + displacement)
opcode reg results in: ld reg, opcode (x + displacement)
(so we'd get "ld l, rl (ix+dd)" instead of "rl ixl")
those starting with 01 (bit):
bit n,whatever > bit n,(x + displacement)
those starting with 10 or 11 (res and set):
opcode n,(hl) results in: opcode n,(x + displacement)
opcode n,reg results in: ld reg, opcode n,(x + displacement)
RL (IX+00) = DD CB 00 16
SRL (IY+00) = FD CB 00 3E
Look into the source; ixl and iyl may be defined as macros.
what is an opcode?
I think that it is something like "OperationCode" (Machine Code) for the microprocessor ... There are some spaces on the 255 combinations (8-bit) that the Z80 microprocessor use.
It could be Hexadecimal ,Binary, Decimal or even others. Into the Z80 Manual there are several opcodes listed.
You can download the manual here. It is *FREE*.
Yukio: hexadecimal/binary/decimal radices are just methods to represent real numbers. A convention is that opcodes are always represented in hexadecimal when listed with mnemonics (the textual representation of the opcode, like LD A,<x> ) or in binary when specified in an instruction set specification: this allows for generalities in the opcodes to be identified easily, which in turn identifies similarities in the configuration of a processor's data path.
