POP

Pop the top value from the SP stack and assign it to the specified register.

Opcode	Bytes	Cycles	Form	Example
$30	2	3	pop b:_	pop b:1
$31	2	3	pop p:_	pop p:2
$32	2	3	pop i:_	pop i:4
$1a	1	2	pop fp	pop fp
$1b	1	2	pop gp	pop gp
$1c	1	2	pop ip	pop ip
$1d	1	2	pop flags	pop flags

Notes

• The SP stack is commonly used to store local variables and return addresses for function calls.

• The SP stack grows forwards (pushing increases the sp register), whereas the GP stack grows backwards. (The "top" of the GP stack is actually the lowest memory address.)

• pop undoes the action of push.

• For example, the effect of pop p:6 is to add 2 to the sp register, because p:6 is a pair register. Then two bytes are read from the memory address indicated by sp and stored in p:6.

• pop ip undoes the action of push return ip. This pair of instructions is used to call subroutines, for example Hybrix function calls.

• pop flags pops the CPU flags as a single byte.

• Aside from the pop flags form, the pop instruction does not affect the CPU condition flags.