58 lines
831 B
ArmAsm
58 lines
831 B
ArmAsm
.define .rck
|
|
.sect .text
|
|
.sect .rom
|
|
.sect .data
|
|
.sect .bss
|
|
.sect .text
|
|
|
|
! Range check
|
|
! Expects on stack: address of range check descriptor
|
|
! index
|
|
! Yields index on stack unchanged
|
|
! Causes a trap if index is out of bounds
|
|
|
|
.rck: pop h
|
|
shld .retadr
|
|
mov h,b
|
|
mov l,c
|
|
shld .bcreg
|
|
|
|
pop h ! hl = return address
|
|
pop d ! de = index
|
|
mov c,m ! bc = lower bound
|
|
inx h
|
|
mov b,m
|
|
inx h
|
|
mov a,d
|
|
xra b
|
|
jm 1f ! jump if index and l.b. have different signs
|
|
mov a,e
|
|
sub c
|
|
mov a,d
|
|
sbb b
|
|
jmp 2f
|
|
|
|
1: xra b ! now a = d again
|
|
2: cm erange ! trap if index too small
|
|
|
|
mov c,m
|
|
inx h
|
|
mov b,m
|
|
mov a,d
|
|
xra b
|
|
jm 1f ! jump if index and u.b. have different signs
|
|
mov a,c
|
|
sub e
|
|
mov a,b
|
|
sbb d
|
|
jmp 2f
|
|
|
|
1: xra d ! now a = b
|
|
2: cm erange ! trap if index is too large
|
|
|
|
lhld .bcreg
|
|
mov b,h
|
|
mov c,l
|
|
lhld .retadr
|
|
pchl
|