/* Optimized version of the standard memcpy() function.
This file is part of the GNU C Library.
Copyright (C) 2000, 2001 Free Software Foundation, Inc.
Contributed by Dan Pop <Dan.Pop@cern.ch>.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
/* Return: dest
Inputs:
in0: dest
in1: src
in2: byte count
An assembly implementation of the algorithm used by the generic C
version from glibc. The case when all three arguments are multiples
of 8 is treated separatedly, for extra performance.
In this form, it assumes little endian mode. For big endian mode,
sh1 must be computed using an extra instruction: sub sh1 = 64, sh1
and the order of r[MEMLAT] and r[MEMLAT+1] must be reverted in the
shrp instruction. */
#include <sysdep.h>
#undef ret
#define OP_T_THRES 16
#define OPSIZ 8
#define adest r15
#define saved_pr r17
#define saved_lc r18
#define dest r19
#define src r20
#define len r21
#define asrc r22
#define tmp2 r23
#define tmp3 r24
#define tmp4 r25
#define ptable r26
#define ploop56 r27
#define loopaddr r28
#define sh1 r29
#define loopcnt r30
#define value r31
#define LOOP(shift) \
.align 32 ; \
.loop##shift##: \
(p[0]) ld8 r[0] = [asrc], 8 ; /* w1 */ \
(p[MEMLAT+1]) st8 [dest] = value, 8 ; \
(p[MEMLAT]) shrp value = r[MEMLAT], r[MEMLAT+1], shift ; \
nop.b 0 ; \
nop.b 0 ; \
br.ctop.sptk .loop##shift ; \
br.cond.sptk .cpyfew ; /* deal with the remaining bytes */
#define MEMLAT 21
#define Nrot (((2*MEMLAT+3) + 7) & ~7)
ENTRY(memcpy)
.prologue
alloc r2 = ar.pfs, 3, Nrot - 3, 0, Nrot
.rotr r[MEMLAT + 2], q[MEMLAT + 1]
.rotp p[MEMLAT + 2]
mov ret0 = in0 // return value = dest
.save pr, saved_pr
mov saved_pr = pr // save the predicate registers
.save ar.lc, saved_lc
mov saved_lc = ar.lc // save the loop counter
.body
or tmp3 = in0, in1 ;; // tmp3 = dest | src
or tmp3 = tmp3, in2 // tmp3 = dest | src | len
mov dest = in0 // dest
mov src = in1 // src
mov len = in2 // len
sub tmp2 = r0, in0 // tmp2 = -dest
cmp.eq p6, p0 = in2, r0 // if (len == 0)
(p6) br.cond.spnt .restore_and_exit;;// return dest;
and tmp4 = 7, tmp3 // tmp4 = (dest | src | len) & 7
shr.u loopcnt = len, 4 ;; // loopcnt = len / 16
cmp.ne p6, p0 = tmp4, r0 // if ((dest | src | len) & 7 != 0)
(p6) br.cond.sptk .next // goto next;
// The optimal case, when dest, src and len are all multiples of 8
and tmp3 = 0xf, len // tmp3 = len % 16
mov pr.rot = 1 << 16 // set rotating predicates
mov ar.ec = MEMLAT + 1 ;; // set the epilog counter
cmp.ne p6, p0 = tmp3, r0 // do we have to copy an extra word?
adds loopcnt = -1, loopcnt;; // --loopcnt
(p6) ld8 value = [src], 8;;
(p6) st8 [dest] = value, 8 // copy the "extra" word
mov ar.lc = loopcnt // set the loop counter
cmp.eq p6, p0 = 8, len
(p6) br.cond.spnt .restore_and_exit;;// there was only one word to copy
adds adest = 8, dest
adds asrc = 8, src ;;
.align 32
.l0:
(p[0]) ld8 r[0] = [src], 16
(p[0]) ld8 q[0] = [asrc], 16
(p[MEMLAT]) st8 [dest] = r[MEMLAT], 16
(p[MEMLAT]) st8 [adest] = q[MEMLAT], 16
br.ctop.dptk .l0 ;;
mov pr = saved_pr, -1 // restore the predicate registers
mov ar.lc = saved_lc // restore the loop counter
br.ret.sptk.many b0
.next:
cmp.ge p6, p0 = OP_T_THRES, len // is len <= OP_T_THRES
and loopcnt = 7, tmp2 // loopcnt = -dest % 8
(p6) br.cond.spnt .cpyfew // copy byte by byte
;;
cmp.eq p6, p0 = loopcnt, r0
(p6) br.cond.sptk .dest_aligned
sub len = len, loopcnt // len -= -dest % 8
adds loopcnt = -1, loopcnt // --loopcnt
;;
mov ar.lc = loopcnt
.l1: // copy -dest % 8 bytes
ld1 value = [src], 1 // value = *src++
;;
st1 [dest] = value, 1 // *dest++ = value
br.cloop.dptk .l1 ;;
.dest_aligned:
and sh1 = 7, src // sh1 = src % 8
and tmp2 = -8, len // tmp2 = len & -OPSIZ
and asrc = -8, src // asrc = src & -OPSIZ -- align src
shr.u loopcnt = len, 3 // loopcnt = len / 8
and len = 7, len;; // len = len % 8
adds loopcnt = -1, loopcnt // --loopcnt
addl tmp4 = @ltoff(.table), gp
addl tmp3 = @ltoff(.loop56), gp
mov ar.ec = MEMLAT + 1 // set EC
mov pr.rot = 1 << 16;; // set rotating predicates
mov ar.lc = loopcnt // set LC
cmp.eq p6, p0 = sh1, r0 // is the src aligned?
(p6) br.cond.sptk .src_aligned
add src = src, tmp2 // src += len & -OPSIZ
shl sh1 = sh1, 3 // sh1 = 8 * (src % 8)
ld8 ploop56 = [tmp3] // ploop56 = &loop56
ld8 ptable = [tmp4];; // ptable = &table
add tmp3 = ptable, sh1;; // tmp3 = &table + sh1
mov ar.ec = MEMLAT + 1 + 1 // one more pass needed
ld8 tmp4 = [tmp3];; // tmp4 = loop offset
sub loopaddr = ploop56,tmp4 // loopadd = &loop56 - loop offset
ld8 r[1] = [asrc], 8;; // w0
mov b6 = loopaddr;;
br b6 // jump to the appropriate loop
LOOP(8)
LOOP(16)
LOOP(24)
LOOP(32)
LOOP(40)
LOOP(48)
LOOP(56)
.src_aligned:
.l3:
(p[0]) ld8 r[0] = [src], 8
(p[MEMLAT]) st8 [dest] = r[MEMLAT], 8
br.ctop.dptk .l3 ;;
.cpyfew:
cmp.eq p6, p0 = len, r0 // is len == 0 ?
adds len = -1, len // --len;
(p6) br.cond.spnt .restore_and_exit ;;
mov ar.lc = len
.l4:
ld1 value = [src], 1
;;
st1 [dest] = value, 1
br.cloop.dptk .l4 ;;
.restore_and_exit:
mov pr = saved_pr, -1 // restore the predicate registers
mov ar.lc = saved_lc // restore the loop counter
br.ret.sptk.many b0
.align 8
.table:
data8 0 // dummy entry
data8 .loop56 - .loop8
data8 .loop56 - .loop16
data8 .loop56 - .loop24
data8 .loop56 - .loop32
data8 .loop56 - .loop40
data8 .loop56 - .loop48
data8 .loop56 - .loop56
END(memcpy)