ack/mach/i80/libem/sri2.s

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ArmAsm
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1985-03-18 12:46:51 +00:00
.define .sri2
1987-01-28 18:57:04 +00:00
.sect .text
.sect .rom
.sect .data
.sect .bss
.sect .text
1985-03-18 12:46:51 +00:00
! Shift 16 bits signed or unsigned integer right
! Expects in a-reg.: 1 if signed integer
! 0 if unsigned integer
! Expects on stack: number of shifts
! number to be shifted
! Yields in de-reg.: result
.sri2: pop h
shld .retadr
pop h !hl = number of shifts
pop d !de = number to be shifted
mvi h,0
ora a
jz 1f !jump if unsigned integer
mov a,d
ral
jnc 1f !jump if positive signed integer
mvi h,255 !now h=1 if negative signed number, h=0 otherwise.
1: mov a,l !return 0 or -1 if hl>=16
cpi 16
jnc 3f
2: dcr l
jm 4f
mov a,h
rar !set carry bit correct
mov a,d
rar
mov d,a
mov a,e
rar
mov e,a
jmp 2b
3: mov d,h
mov e,h
4: lhld .retadr
pchl