popcount.asm
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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
- dnl modify it under the terms of the GNU Lesser General Public License as
- dnl published by the Free Software Foundation; either version 3 of the
- dnl License, or (at your option) any later version.
- dnl
- dnl The GNU MP Library is distributed in the hope that it will be useful,
- dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
- dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- dnl Lesser General Public License for more details.
- dnl
- dnl You should have received a copy of the GNU Lesser General Public License
- dnl along with the GNU MP Library. If not, see http://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()