source/libs/gmp/gmp-src/mpn/alpha/ev67/popcount.asm

   1 dnl  Alpha ev67 mpn_popcount -- mpn bit population count.
   2
   3 dnl  Copyright 2003, 2005 Free Software Foundation, Inc.
   4
   5 dnl  This file is part of the GNU MP Library.
   6 dnl
   7 dnl  The GNU MP Library is free software; you can redistribute it and/or modify
   8 dnl  it under the terms of either:
   9 dnl
  10 dnl    * the GNU Lesser General Public License as published by the Free
  11 dnl      Software Foundation; either version 3 of the License, or (at your
  12 dnl      option) any later version.
  13 dnl
  14 dnl  or
  15 dnl
  16 dnl    * the GNU General Public License as published by the Free Software
  17 dnl      Foundation; either version 2 of the License, or (at your option) any
  18 dnl      later version.
  19 dnl
  20 dnl  or both in parallel, as here.
  21 dnl
  22 dnl  The GNU MP Library is distributed in the hope that it will be useful, but
  23 dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  24 dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  25 dnl  for more details.
  26 dnl
  27 dnl  You should have received copies of the GNU General Public License and the
  28 dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,
  29 dnl  see https://www.gnu.org/licenses/.
  30
  31 include(`../config.m4')
  32
  33
  34 C ev67: 1.5 cycles/limb
  35
  36
  37 C unsigned long mpn_popcount (mp_srcptr src, mp_size_t size);
  38 C
  39 C This schedule seems necessary for the full 1.5 c/l, the IQ can't quite hide
  40 C all latencies, the addq's must be deferred to the next iteration.
  41 C
  42 C Since we need just 3 instructions per limb, further unrolling could approach
  43 C 1.0 c/l.
  44 C
  45 C The main loop processes two limbs at a time.  An odd size is handled by
  46 C processing src[0] at the start.  If the size is even that result is
  47 C discarded, and src[0] is repeated by the main loop.
  48 C
  49
  50 ASM_START()
  51 PROLOGUE(mpn_popcount)
  52
  53         C r16   src
  54         C r17   size
  55
  56         ldq     r0, 0(r16)              C L0  src[0]
  57         and     r17, 1, r8              C U1  1 if size odd
  58         srl     r17, 1, r17             C U0  size, limb pairs
  59
  60         s8addq  r8, r16, r16            C L1  src++ if size odd
  61         ctpop   r0, r0                  C U0
  62         beq     r17, L(one)             C U1  if size==1
  63
  64         cmoveq  r8, r31, r0             C L   discard first limb if size even
  65         clr     r3                      C L
  66
  67         clr     r4                      C L
  68         unop                            C U
  69         unop                            C L
  70         unop                            C U
  71
  72
  73         ALIGN(16)
  74 L(top):
  75         C r0    total accumulating
  76         C r3    pop 0
  77         C r4    pop 1
  78         C r16   src, incrementing
  79         C r17   size, decrementing
  80
  81         ldq     r1, 0(r16)              C L
  82         ldq     r2, 8(r16)              C L
  83         lda     r16, 16(r16)            C U
  84         lda     r17, -1(r17)            C U
  85
  86         addq    r0, r3, r0              C L
  87         addq    r0, r4, r0              C L
  88         ctpop   r1, r3                  C U0
  89         ctpop   r2, r4                  C U0
  90
  91         ldl     r31, 512(r16)           C L     prefetch
  92         bne     r17, L(top)             C U
  93
  94
  95         addq    r0, r3, r0              C L
  96         addq    r0, r4, r0              C U
  97 L(one):
  98         ret     r31, (r26), 1           C L0
  99
 100 EPILOGUE()
 101 ASM_END()