mirror of
https://github.com/torvalds/linux
synced 2024-11-05 18:23:50 +00:00
7caaeabb17
From: Al Viro <viro@ZenIV.linux.org.uk> Instead of playing all of these hand-coded assembler aliasing games, just translate symbol names in the name space ".sym" to "_Sym" at module load time. Signed-off-by: David S. Miller <davem@davemloft.net>
357 lines
7 KiB
ArmAsm
357 lines
7 KiB
ArmAsm
/* $Id: udiv.S,v 1.4 1996/09/30 02:22:38 davem Exp $
|
|
* udiv.S: This routine was taken from glibc-1.09 and is covered
|
|
* by the GNU Library General Public License Version 2.
|
|
*/
|
|
|
|
|
|
/* This file is generated from divrem.m4; DO NOT EDIT! */
|
|
/*
|
|
* Division and remainder, from Appendix E of the Sparc Version 8
|
|
* Architecture Manual, with fixes from Gordon Irlam.
|
|
*/
|
|
|
|
/*
|
|
* Input: dividend and divisor in %o0 and %o1 respectively.
|
|
*
|
|
* m4 parameters:
|
|
* .udiv name of function to generate
|
|
* div div=div => %o0 / %o1; div=rem => %o0 % %o1
|
|
* false false=true => signed; false=false => unsigned
|
|
*
|
|
* Algorithm parameters:
|
|
* N how many bits per iteration we try to get (4)
|
|
* WORDSIZE total number of bits (32)
|
|
*
|
|
* Derived constants:
|
|
* TOPBITS number of bits in the top decade of a number
|
|
*
|
|
* Important variables:
|
|
* Q the partial quotient under development (initially 0)
|
|
* R the remainder so far, initially the dividend
|
|
* ITER number of main division loop iterations required;
|
|
* equal to ceil(log2(quotient) / N). Note that this
|
|
* is the log base (2^N) of the quotient.
|
|
* V the current comparand, initially divisor*2^(ITER*N-1)
|
|
*
|
|
* Cost:
|
|
* Current estimate for non-large dividend is
|
|
* ceil(log2(quotient) / N) * (10 + 7N/2) + C
|
|
* A large dividend is one greater than 2^(31-TOPBITS) and takes a
|
|
* different path, as the upper bits of the quotient must be developed
|
|
* one bit at a time.
|
|
*/
|
|
|
|
|
|
.globl .udiv
|
|
.globl _Udiv
|
|
.udiv:
|
|
_Udiv: /* needed for export */
|
|
|
|
! Ready to divide. Compute size of quotient; scale comparand.
|
|
orcc %o1, %g0, %o5
|
|
bne 1f
|
|
mov %o0, %o3
|
|
|
|
! Divide by zero trap. If it returns, return 0 (about as
|
|
! wrong as possible, but that is what SunOS does...).
|
|
ta ST_DIV0
|
|
retl
|
|
clr %o0
|
|
|
|
1:
|
|
cmp %o3, %o5 ! if %o1 exceeds %o0, done
|
|
blu Lgot_result ! (and algorithm fails otherwise)
|
|
clr %o2
|
|
|
|
sethi %hi(1 << (32 - 4 - 1)), %g1
|
|
|
|
cmp %o3, %g1
|
|
blu Lnot_really_big
|
|
clr %o4
|
|
|
|
! Here the dividend is >= 2**(31-N) or so. We must be careful here,
|
|
! as our usual N-at-a-shot divide step will cause overflow and havoc.
|
|
! The number of bits in the result here is N*ITER+SC, where SC <= N.
|
|
! Compute ITER in an unorthodox manner: know we need to shift V into
|
|
! the top decade: so do not even bother to compare to R.
|
|
1:
|
|
cmp %o5, %g1
|
|
bgeu 3f
|
|
mov 1, %g7
|
|
|
|
sll %o5, 4, %o5
|
|
|
|
b 1b
|
|
add %o4, 1, %o4
|
|
|
|
! Now compute %g7.
|
|
2:
|
|
addcc %o5, %o5, %o5
|
|
bcc Lnot_too_big
|
|
add %g7, 1, %g7
|
|
|
|
! We get here if the %o1 overflowed while shifting.
|
|
! This means that %o3 has the high-order bit set.
|
|
! Restore %o5 and subtract from %o3.
|
|
sll %g1, 4, %g1 ! high order bit
|
|
srl %o5, 1, %o5 ! rest of %o5
|
|
add %o5, %g1, %o5
|
|
|
|
b Ldo_single_div
|
|
sub %g7, 1, %g7
|
|
|
|
Lnot_too_big:
|
|
3:
|
|
cmp %o5, %o3
|
|
blu 2b
|
|
nop
|
|
|
|
be Ldo_single_div
|
|
nop
|
|
/* NB: these are commented out in the V8-Sparc manual as well */
|
|
/* (I do not understand this) */
|
|
! %o5 > %o3: went too far: back up 1 step
|
|
! srl %o5, 1, %o5
|
|
! dec %g7
|
|
! do single-bit divide steps
|
|
!
|
|
! We have to be careful here. We know that %o3 >= %o5, so we can do the
|
|
! first divide step without thinking. BUT, the others are conditional,
|
|
! and are only done if %o3 >= 0. Because both %o3 and %o5 may have the high-
|
|
! order bit set in the first step, just falling into the regular
|
|
! division loop will mess up the first time around.
|
|
! So we unroll slightly...
|
|
Ldo_single_div:
|
|
subcc %g7, 1, %g7
|
|
bl Lend_regular_divide
|
|
nop
|
|
|
|
sub %o3, %o5, %o3
|
|
mov 1, %o2
|
|
|
|
b Lend_single_divloop
|
|
nop
|
|
Lsingle_divloop:
|
|
sll %o2, 1, %o2
|
|
bl 1f
|
|
srl %o5, 1, %o5
|
|
! %o3 >= 0
|
|
sub %o3, %o5, %o3
|
|
b 2f
|
|
add %o2, 1, %o2
|
|
1: ! %o3 < 0
|
|
add %o3, %o5, %o3
|
|
sub %o2, 1, %o2
|
|
2:
|
|
Lend_single_divloop:
|
|
subcc %g7, 1, %g7
|
|
bge Lsingle_divloop
|
|
tst %o3
|
|
|
|
b,a Lend_regular_divide
|
|
|
|
Lnot_really_big:
|
|
1:
|
|
sll %o5, 4, %o5
|
|
|
|
cmp %o5, %o3
|
|
bleu 1b
|
|
addcc %o4, 1, %o4
|
|
|
|
be Lgot_result
|
|
sub %o4, 1, %o4
|
|
|
|
tst %o3 ! set up for initial iteration
|
|
Ldivloop:
|
|
sll %o2, 4, %o2
|
|
! depth 1, accumulated bits 0
|
|
bl L.1.16
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
! depth 2, accumulated bits 1
|
|
bl L.2.17
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
! depth 3, accumulated bits 3
|
|
bl L.3.19
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
! depth 4, accumulated bits 7
|
|
bl L.4.23
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (7*2+1), %o2
|
|
|
|
L.4.23:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (7*2-1), %o2
|
|
|
|
L.3.19:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
! depth 4, accumulated bits 5
|
|
bl L.4.21
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (5*2+1), %o2
|
|
|
|
L.4.21:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (5*2-1), %o2
|
|
|
|
L.2.17:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
! depth 3, accumulated bits 1
|
|
bl L.3.17
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
! depth 4, accumulated bits 3
|
|
bl L.4.19
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (3*2+1), %o2
|
|
|
|
L.4.19:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (3*2-1), %o2
|
|
|
|
L.3.17:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
! depth 4, accumulated bits 1
|
|
bl L.4.17
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (1*2+1), %o2
|
|
|
|
L.4.17:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (1*2-1), %o2
|
|
|
|
L.1.16:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
! depth 2, accumulated bits -1
|
|
bl L.2.15
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
! depth 3, accumulated bits -1
|
|
bl L.3.15
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
! depth 4, accumulated bits -1
|
|
bl L.4.15
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (-1*2+1), %o2
|
|
|
|
L.4.15:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (-1*2-1), %o2
|
|
|
|
L.3.15:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
! depth 4, accumulated bits -3
|
|
bl L.4.13
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (-3*2+1), %o2
|
|
|
|
L.4.13:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (-3*2-1), %o2
|
|
|
|
L.2.15:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
! depth 3, accumulated bits -3
|
|
bl L.3.13
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
! depth 4, accumulated bits -5
|
|
bl L.4.11
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (-5*2+1), %o2
|
|
|
|
L.4.11:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (-5*2-1), %o2
|
|
|
|
L.3.13:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
! depth 4, accumulated bits -7
|
|
bl L.4.9
|
|
srl %o5,1,%o5
|
|
! remainder is positive
|
|
subcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (-7*2+1), %o2
|
|
|
|
L.4.9:
|
|
! remainder is negative
|
|
addcc %o3,%o5,%o3
|
|
b 9f
|
|
add %o2, (-7*2-1), %o2
|
|
|
|
9:
|
|
Lend_regular_divide:
|
|
subcc %o4, 1, %o4
|
|
bge Ldivloop
|
|
tst %o3
|
|
|
|
bl,a Lgot_result
|
|
! non-restoring fixup here (one instruction only!)
|
|
sub %o2, 1, %o2
|
|
|
|
Lgot_result:
|
|
|
|
retl
|
|
mov %o2, %o0
|
|
|
|
.globl .udiv_patch
|
|
.udiv_patch:
|
|
wr %g0, 0x0, %y
|
|
nop
|
|
nop
|
|
retl
|
|
udiv %o0, %o1, %o0
|
|
nop
|