103 lines
2.6 KiB
NASM
103 lines
2.6 KiB
NASM
dnl Alpha ev67 mpn_hamdist -- mpn hamming distance.
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dnl Copyright 2003, 2005 Free Software Foundation, Inc.
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dnl This file is part of the GNU MP Library.
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dnl
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dnl The GNU MP Library is free software; you can redistribute it and/or
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dnl modify it under the terms of the GNU Lesser General Public License as
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dnl published by the Free Software Foundation; either version 2.1 of the
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dnl License, or (at your option) any later version.
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dnl
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dnl The GNU MP Library is distributed in the hope that it will be useful,
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dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
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dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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dnl Lesser General Public License for more details.
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dnl
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dnl You should have received a copy of the GNU Lesser General Public
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dnl License along with the GNU MP Library; see the file COPYING.LIB. If
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dnl not, write to the Free Software Foundation, Inc., 51 Franklin Street,
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dnl Fifth Floor, Boston, MA 02110-1301, USA.
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include(`../config.m4')
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C ev67: 2.5 cycles/limb
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C unsigned long mpn_hamdist (mp_srcptr xp, mp_srcptr yp, mp_size_t size);
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C
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C The hope was for 2.0 c/l here, but that isn't achieved. We're limited by
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C renaming register shortage. Since we need 5 instructions per limb, further
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C unrolling could approach 1.5 c/l.
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C
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C The main loop processes two limbs from each operand on each iteration. An
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C odd size is handled by processing xp[0]^yp[0] at the start. If the size
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C is even that result is discarded, and is repeated by the main loop.
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C
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ASM_START()
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PROLOGUE(mpn_hamdist)
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C r16 xp
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C r17 yp
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C r18 size
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ldq r1, 0(r16) C L0 xp[0]
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ldq r2, 0(r17) C L1 yp[0]
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and r18, 1, r8 C U1 1 if size odd
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srl r18, 1, r18 C U0 size, limb pairs
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clr r0 C L0 initial total
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s8addq r8, r17, r17 C U1 yp++ if size odd
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s8addq r8, r16, r16 C L1 xp++ if size odd
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clr r6 C U0 dummy initial xor 1
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xor r1, r2, r5 C L initial xor 0
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beq r18, L(one) C U if size==1
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cmoveq r8, r31, r5 C L discard first limb if size even
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unop C U
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ALIGN(16)
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L(top):
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C r0 total accumulating
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C r7 xor 0
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C r8 xor 1
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C r16 xp, incrementing
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C r17 yp, incrementing
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C r18 size, limb pairs, decrementing
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ldq r1, 0(r16) C L
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ldq r2, 0(r17) C L
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ctpop r5, r7 C U0
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lda r16, 16(r16) C U
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ldq r3, -8(r16) C L
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ldq r4, 8(r17) C L
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ctpop r6, r8 C U0
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lda r17, 16(r17) C U
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ldl r31, 256(r16) C L prefetch
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ldl r31, 256(r17) C L prefetch
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xor r1, r2, r5 C U
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lda r18, -1(r18) C U
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xor r3, r4, r6 C U
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addq r0, r7, r0 C L
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addq r0, r8, r0 C L
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bne r18, L(top) C U
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ctpop r6, r8 C U0
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addq r0, r8, r0 C L
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L(one):
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ctpop r5, r7 C U0
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addq r0, r7, r0 C L
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ret r31, (r26), 1 C L0
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EPILOGUE()
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ASM_END()
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