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LLCALL (JKHL)     Far Call     Rabbit 4000/5000 Instruction

Opcode	Instruction	Operation
ED FA	LLCALL (JKHL)	(SP-1) = LXPChigh (SP-2) = LXPClow (SP-3) = PChigh (SP-4) = PClow PC = HL LXPC = JK SP = SP-4

Clocks	8-Bit Access	16-Bit Unaligned	16-Bit Aligned
Rabbit 4000	19	n/a	n/a
Rabbit 5000	20	20	18

Flags				ALTD			IOI/IOE
S	Z	L/V	C	F	R	SP	S	D
-	-	-	-

Description

This instruction is similar to the LCALL¹ instruction in that it transfers program execution to the subroutine address specified by the 16-bit constant mn and allows calls to made to a computed address in extended memory. The LLCALL instruction uses the 12-bit LXPC of the Rabbit 4000 or 5000 processor instead of the 8-bit XPC of earlier Rabbit processors. Note that the value of LXPC and consequently the address space defined by the LXPC is dynamically changed with the LLCALL instructions.

In the LLCALL instruction, first LXPC is pushed onto the stack, high-order byte first, then the low-order byte. Next, PC is pushed onto the stack, high-order byte first, then the low-order byte. Then PC is loaded with the data in HL and XPC is loaded with the data in JK. SP is then updated.

¹ Avoid mixing LCALL and LLCALL instructions. When LCALL pushes the XPC, it also clears the upper bits of the LXPC.