1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
77 lines
2.7 KiB
ArmAsm
77 lines
2.7 KiB
ArmAsm
# S/390 __udiv_qrnnd
|
|
|
|
# r2 : &__r
|
|
# r3 : upper half of 64 bit word n
|
|
# r4 : lower half of 64 bit word n
|
|
# r5 : divisor d
|
|
# the reminder r of the division is to be stored to &__r and
|
|
# the quotient q is to be returned
|
|
|
|
.text
|
|
.globl __udiv_qrnnd
|
|
__udiv_qrnnd:
|
|
st %r2,24(%r15) # store pointer to reminder for later
|
|
lr %r0,%r3 # reload n
|
|
lr %r1,%r4
|
|
ltr %r2,%r5 # reload and test divisor
|
|
jp 5f
|
|
# divisor >= 0x80000000
|
|
srdl %r0,2 # n/4
|
|
srl %r2,1 # d/2
|
|
slr %r1,%r2 # special case if last bit of d is set
|
|
brc 3,0f # (n/4) div (n/2) can overflow by 1
|
|
ahi %r0,-1 # trick: subtract n/2, then divide
|
|
0: dr %r0,%r2 # signed division
|
|
ahi %r1,1 # trick part 2: add 1 to the quotient
|
|
# now (n >> 2) = (d >> 1) * %r1 + %r0
|
|
lhi %r3,1
|
|
nr %r3,%r1 # test last bit of q
|
|
jz 1f
|
|
alr %r0,%r2 # add (d>>1) to r
|
|
1: srl %r1,1 # q >>= 1
|
|
# now (n >> 2) = (d&-2) * %r1 + %r0
|
|
lhi %r3,1
|
|
nr %r3,%r5 # test last bit of d
|
|
jz 2f
|
|
slr %r0,%r1 # r -= q
|
|
brc 3,2f # borrow ?
|
|
alr %r0,%r5 # r += d
|
|
ahi %r1,-1
|
|
2: # now (n >> 2) = d * %r1 + %r0
|
|
alr %r1,%r1 # q <<= 1
|
|
alr %r0,%r0 # r <<= 1
|
|
brc 12,3f # overflow on r ?
|
|
slr %r0,%r5 # r -= d
|
|
ahi %r1,1 # q += 1
|
|
3: lhi %r3,2
|
|
nr %r3,%r4 # test next to last bit of n
|
|
jz 4f
|
|
ahi %r0,1 # r += 1
|
|
4: clr %r0,%r5 # r >= d ?
|
|
jl 6f
|
|
slr %r0,%r5 # r -= d
|
|
ahi %r1,1 # q += 1
|
|
# now (n >> 1) = d * %r1 + %r0
|
|
j 6f
|
|
5: # divisor < 0x80000000
|
|
srdl %r0,1
|
|
dr %r0,%r2 # signed division
|
|
# now (n >> 1) = d * %r1 + %r0
|
|
6: alr %r1,%r1 # q <<= 1
|
|
alr %r0,%r0 # r <<= 1
|
|
brc 12,7f # overflow on r ?
|
|
slr %r0,%r5 # r -= d
|
|
ahi %r1,1 # q += 1
|
|
7: lhi %r3,1
|
|
nr %r3,%r4 # isolate last bit of n
|
|
alr %r0,%r3 # r += (n & 1)
|
|
clr %r0,%r5 # r >= d ?
|
|
jl 8f
|
|
slr %r0,%r5 # r -= d
|
|
ahi %r1,1 # q += 1
|
|
8: # now n = d * %r1 + %r0
|
|
l %r2,24(%r15)
|
|
st %r0,0(%r2)
|
|
lr %r2,%r1
|
|
br %r14
|
|
.end __udiv_qrnnd
|