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dnl Alpha ev67 mpn_popcount -- mpn bit population count.
dnl Copyright 2003, 2005 Free Software Foundation, Inc.
dnl This file is part of the GNU MP Library.
dnl
dnl The GNU MP Library is free software; you can redistribute it and/or modify
dnl it under the terms of either:
dnl
dnl * the GNU Lesser General Public License as published by the Free
dnl Software Foundation; either version 3 of the License, or (at your
dnl option) any later version.
dnl
dnl or
dnl
dnl * the GNU General Public License as published by the Free Software
dnl Foundation; either version 2 of the License, or (at your option) any
dnl later version.
dnl
dnl or both in parallel, as here.
dnl
dnl The GNU MP Library is distributed in the hope that it will be useful, but
dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
dnl for more details.
dnl
dnl You should have received copies of the GNU General Public License and the
dnl GNU Lesser General Public License along with the GNU MP Library. If not,
dnl see https://www.gnu.org/licenses/.
include(`../config.m4')
C ev67: 1.5 cycles/limb
C unsigned long mpn_popcount (mp_srcptr src, mp_size_t size);
C
C This schedule seems necessary for the full 1.5 c/l, the IQ can't quite hide
C all latencies, the addq's must be deferred to the next iteration.
C
C Since we need just 3 instructions per limb, further unrolling could approach
C 1.0 c/l.
C
C The main loop processes two limbs at a time. An odd size is handled by
C processing src[0] at the start. If the size is even that result is
C discarded, and src[0] is repeated by the main loop.
C
ASM_START()
PROLOGUE(mpn_popcount)
C r16 src
C r17 size
ldq r0, 0(r16) C L0 src[0]
and r17, 1, r8 C U1 1 if size odd
srl r17, 1, r17 C U0 size, limb pairs
s8addq r8, r16, r16 C L1 src++ if size odd
ctpop r0, r0 C U0
beq r17, L(one) C U1 if size==1
cmoveq r8, r31, r0 C L discard first limb if size even
clr r3 C L
clr r4 C L
unop C U
unop C L
unop C U
ALIGN(16)
L(top):
C r0 total accumulating
C r3 pop 0
C r4 pop 1
C r16 src, incrementing
C r17 size, decrementing
ldq r1, 0(r16) C L
ldq r2, 8(r16) C L
lda r16, 16(r16) C U
lda r17, -1(r17) C U
addq r0, r3, r0 C L
addq r0, r4, r0 C L
ctpop r1, r3 C U0
ctpop r2, r4 C U0
ldl r31, 512(r16) C L prefetch
bne r17, L(top) C U
addq r0, r3, r0 C L
addq r0, r4, r0 C U
L(one):
ret r31, (r26), 1 C L0
EPILOGUE()
ASM_END()
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