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 TEXT ·CumSum(SB), NOSPLIT, $0
10 MOVQ dst_base+0(FP), DI // DI = &dst
11 MOVQ dst_len+8(FP), CX // CX = len(dst)
12 MOVQ s_base+24(FP), SI // SI = &s
13 CMPQ s_len+32(FP), CX // CX = max( CX, len(s) )
14 CMOVQLE s_len+32(FP), CX
15 MOVQ CX, ret_len+56(FP) // len(ret) = CX
16 CMPQ CX, $0 // if CX == 0 { return }
19 PXOR X5, X5 // p_sum = 0
21 ANDQ $3, BX // BX = CX % 4
22 SHRQ $2, CX // CX = floor( CX / 4 )
23 JZ cs_tail_start // if CX == 0 { goto cs_tail_start }
25 cs_loop: // Loop unrolled 4x do {
26 MOVUPS (SI)(AX*8), X0 // X0 = s[i:i+1]
27 MOVUPS 16(SI)(AX*8), X2
28 MOVAPS X0, X1 // X1 = X0
30 SHUFPD $1, X1, X1 // { X1[0], X1[1] } = { X1[1], X1[0] }
32 ADDPD X0, X1 // X1 += X0
34 SHUFPD $2, X1, X0 // { X0[0], X0[1] } = { X0[0], X1[1] }
35 SHUFPD $3, X1, X1 // { X1[0], X1[1] } = { X1[1], X1[1] }
38 ADDPD X5, X0 // X0 += p_sum
39 ADDPD X1, X5 // p_sum += X1
41 MOVUPS X0, (DI)(AX*8) // dst[i] = X0
42 MOVUPS X2, 16(DI)(AX*8)
45 LOOP cs_loop // } while --CX > 0
47 // if BX == 0 { return }
51 cs_tail_start: // Reset loop registers
52 MOVQ BX, CX // Loop counter: CX = BX
55 ADDSD (SI)(AX*8), X5 // p_sum *= s[i]
56 MOVSD X5, (DI)(AX*8) // dst[i] = p_sum
58 LOOP cs_tail // } while --CX > 0
61 MOVQ DI, ret_base+48(FP) // &ret = &dst
62 MOVQ dst_cap+16(FP), SI // cap(ret) = cap(dst)
63 MOVQ SI, ret_cap+64(FP)