57 lines
1,002 B
ArmAsm
57 lines
1,002 B
ArmAsm
.define .csa
|
|
.sect .text
|
|
.sect .rom
|
|
.sect .data
|
|
.sect .bss
|
|
.sect .text
|
|
|
|
! Case jump
|
|
! Expects on stack: address of case descriptor
|
|
! case index
|
|
! This is not a subroutine, but just a piece of code that computes
|
|
! the jump address and jumps to it.
|
|
! Traps if resulting address is zero.
|
|
|
|
.csa: pop h !hl = address of case descriptor
|
|
pop d !de = index
|
|
push b !save localbase
|
|
mov c,m
|
|
inx h
|
|
mov b,m
|
|
inx h
|
|
push b !save default pointer on stack
|
|
mov a,e
|
|
sub m
|
|
inx h
|
|
mov c,a
|
|
mov a,d
|
|
sbb m
|
|
inx h
|
|
mov b,a !bc = index - lower bound
|
|
jc 1f !get default pointer
|
|
mov a,m
|
|
inx h
|
|
sub c
|
|
mov a,m
|
|
inx h
|
|
sbb b
|
|
jc 1f !upper-lower should be >= index-lower
|
|
dad b
|
|
dad b !hl now points to the wanted pointer
|
|
mov a,m
|
|
inx h
|
|
mov h,m
|
|
mov l,a !hl = pointer for index
|
|
ora h
|
|
jz 1f !get default pointer if pointer = 0
|
|
pop b !remove default pointer
|
|
pop b !localbase
|
|
pchl !jump!!!!
|
|
|
|
1: pop h !get default pointer
|
|
mov a,l
|
|
ora h
|
|
cz ecase !trap
|
|
pop b !restore localbase
|
|
pchl !jump!!!!
|
|
|