1 // Copyright ©2016 The Gonum Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
5 // +build !noasm,!appengine
9 // func L1Dist(s, t []float64) float64
10 TEXT ·L1Dist(SB), NOSPLIT, $0
11 MOVQ s_base+0(FP), DI // DI = &s
12 MOVQ t_base+24(FP), SI // SI = &t
13 MOVQ s_len+8(FP), CX // CX = len(s)
14 CMPQ t_len+32(FP), CX // CX = max( CX, len(t) )
15 CMOVQLE t_len+32(FP), CX
16 PXOR X3, X3 // norm = 0
17 CMPQ CX, $0 // if CX == 0 { return 0 }
21 ANDQ $1, BX // BX = CX % 2
22 SHRQ $1, CX // CX = floor( CX / 2 )
23 JZ l1_tail_start // if CX == 0 { return 0 }
25 l1_loop: // Loop unrolled 2x do {
26 MOVUPS (SI)(AX*8), X0 // X0 = t[i:i+1]
27 MOVUPS (DI)(AX*8), X1 // X1 = s[i:i+1]
31 MAXPD X1, X0 // X0 = max( X0 - X1, X1 - X0 )
32 ADDPD X0, X3 // norm += X0
34 LOOP l1_loop // } while --CX > 0
35 CMPQ BX, $0 // if BX == 0 { return }
38 l1_tail_start: // Reset loop registers
39 MOVQ BX, CX // Loop counter: CX = BX
40 PXOR X0, X0 // reset X0, X1 to break dependencies
44 MOVSD (SI)(AX*8), X0 // X0 = t[i]
45 MOVSD (DI)(AX*8), X1 // x1 = s[i]
49 MAXSD X1, X0 // X0 = max( X0 - X1, X1 - X0 )
50 ADDSD X0, X3 // norm += X0
55 ADDSD X3, X2 // X2 = X3[1] + X3[0]
56 MOVSD X2, ret+48(FP) // return X2