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83 lines
2.2 KiB
ArmAsm
83 lines
2.2 KiB
ArmAsm
// Copyright ©2016 The Gonum Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build !noasm,!appengine,!safe
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#include "textflag.h"
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// func L1Norm(x []float64) float64
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TEXT ·L1Norm(SB), NOSPLIT, $0
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MOVQ x_base+0(FP), SI // SI = &x
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MOVQ x_len+8(FP), CX // CX = len(x)
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XORQ AX, AX // i = 0
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PXOR X0, X0 // p_sum_i = 0
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PXOR X1, X1
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PXOR X2, X2
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PXOR X3, X3
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PXOR X4, X4
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PXOR X5, X5
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PXOR X6, X6
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PXOR X7, X7
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CMPQ CX, $0 // if CX == 0 { return 0 }
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JE absum_end
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MOVQ CX, BX
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ANDQ $7, BX // BX = len(x) % 8
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SHRQ $3, CX // CX = floor( len(x) / 8 )
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JZ absum_tail_start // if CX == 0 { goto absum_tail_start }
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absum_loop: // do {
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// p_sum += max( p_sum + x[i], p_sum - x[i] )
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MOVUPS (SI)(AX*8), X8 // X_i = x[i:i+1]
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MOVUPS 16(SI)(AX*8), X9
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MOVUPS 32(SI)(AX*8), X10
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MOVUPS 48(SI)(AX*8), X11
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ADDPD X8, X0 // p_sum_i += X_i ( positive values )
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ADDPD X9, X2
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ADDPD X10, X4
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ADDPD X11, X6
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SUBPD X8, X1 // p_sum_(i+1) -= X_i ( negative values )
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SUBPD X9, X3
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SUBPD X10, X5
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SUBPD X11, X7
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MAXPD X1, X0 // p_sum_i = max( p_sum_i, p_sum_(i+1) )
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MAXPD X3, X2
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MAXPD X5, X4
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MAXPD X7, X6
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MOVAPS X0, X1 // p_sum_(i+1) = p_sum_i
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MOVAPS X2, X3
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MOVAPS X4, X5
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MOVAPS X6, X7
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ADDQ $8, AX // i += 8
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LOOP absum_loop // } while --CX > 0
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// p_sum_0 = \sum_{i=1}^{3}( p_sum_(i*2) )
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ADDPD X3, X0
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ADDPD X5, X7
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ADDPD X7, X0
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// p_sum_0[0] = p_sum_0[0] + p_sum_0[1]
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MOVAPS X0, X1
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SHUFPD $0x3, X0, X0 // lower( p_sum_0 ) = upper( p_sum_0 )
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ADDSD X1, X0
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CMPQ BX, $0
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JE absum_end // if BX == 0 { goto absum_end }
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absum_tail_start: // Reset loop registers
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MOVQ BX, CX // Loop counter: CX = BX
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XORPS X8, X8 // X_8 = 0
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absum_tail: // do {
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// p_sum += max( p_sum + x[i], p_sum - x[i] )
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MOVSD (SI)(AX*8), X8 // X_8 = x[i]
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MOVSD X0, X1 // p_sum_1 = p_sum_0
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ADDSD X8, X0 // p_sum_0 += X_8
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SUBSD X8, X1 // p_sum_1 -= X_8
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MAXSD X1, X0 // p_sum_0 = max( p_sum_0, p_sum_1 )
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INCQ AX // i++
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LOOP absum_tail // } while --CX > 0
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absum_end: // return p_sum_0
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MOVSD X0, sum+24(FP)
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RET
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