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/*
* User string length functions for kernel
*
* Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
#define isrc r0
#define max r1 /* Do not change! */
#define end r2
#define tmp1 r3
#define obo r6 /* off-by-one */
#define start r7
#define mod8 r8
#define dbuf r15:14
#define dcmp r13:12
/*
* The vector mask version of this turned out *really* badly.
* The hardware loop version also turned out *really* badly.
* Seems straight pointer arithmetic basically wins here.
*/
#define fname __strnlen_user
.text
.global fname
.type fname, @function
.p2align 5 /* why? */
fname:
{
mod8 = and(isrc,#7);
end = add(isrc,max);
start = isrc;
}
{
P0 = cmp.eq(mod8,#0);
mod8 = and(end,#7);
dcmp = #0;
if (P0.new) jump:t dw_loop; /* fire up the oven */
}
alignment_loop:
fail_1: {
tmp1 = memb(start++#1);
}
{
P0 = cmp.eq(tmp1,#0);
if (P0.new) jump:nt exit_found;
P1 = cmp.gtu(end,start);
mod8 = and(start,#7);
}
{
if (!P1) jump exit_error; /* hit the end */
P0 = cmp.eq(mod8,#0);
}
{
if (!P0) jump alignment_loop;
}
dw_loop:
fail_2: {
dbuf = memd(start);
obo = add(start,#1);
}
{
P0 = vcmpb.eq(dbuf,dcmp);
}
{
tmp1 = P0;
P0 = cmp.gtu(end,start);
}
{
tmp1 = ct0(tmp1);
mod8 = and(end,#7);
if (!P0) jump end_check;
}
{
P0 = cmp.eq(tmp1,#32);
if (!P0.new) jump:nt exit_found;
if (!P0.new) start = add(obo,tmp1);
}
{
start = add(start,#8);
jump dw_loop;
} /* might be nice to combine these jumps... */
end_check:
{
P0 = cmp.gt(tmp1,mod8);
if (P0.new) jump:nt exit_error; /* neverfound! */
start = add(obo,tmp1);
}
exit_found:
{
R0 = sub(start,isrc);
jumpr R31;
}
exit_error:
{
R0 = add(max,#1);
jumpr R31;
}
/* Uh, what does the "fixup" return here? */
.falign
fix_1:
{
R0 = #0;
jumpr R31;
}
.size fname,.-fname
.section __ex_table,"a"
.long fail_1,fix_1
.long fail_2,fix_1
.previous
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