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// Copyright ©2016 The Gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !noasm,!gccgo,!safe
#include "textflag.h"
TEXT ·CumSum(SB), NOSPLIT, $0
MOVQ dst_base+0(FP), DI // DI = &dst
MOVQ dst_len+8(FP), CX // CX = len(dst)
MOVQ s_base+24(FP), SI // SI = &s
CMPQ s_len+32(FP), CX // CX = max( CX, len(s) )
CMOVQLE s_len+32(FP), CX
MOVQ CX, ret_len+56(FP) // len(ret) = CX
CMPQ CX, $0 // if CX == 0 { return }
JE cs_end
XORQ AX, AX // i = 0
PXOR X5, X5 // p_sum = 0
MOVQ CX, BX
ANDQ $3, BX // BX = CX % 4
SHRQ $2, CX // CX = floor( CX / 4 )
JZ cs_tail_start // if CX == 0 { goto cs_tail_start }
cs_loop: // Loop unrolled 4x do {
MOVUPS (SI)(AX*8), X0 // X0 = s[i:i+1]
MOVUPS 16(SI)(AX*8), X2
MOVAPS X0, X1 // X1 = X0
MOVAPS X2, X3
SHUFPD $1, X1, X1 // { X1[0], X1[1] } = { X1[1], X1[0] }
SHUFPD $1, X3, X3
ADDPD X0, X1 // X1 += X0
ADDPD X2, X3
SHUFPD $2, X1, X0 // { X0[0], X0[1] } = { X0[0], X1[1] }
SHUFPD $3, X1, X1 // { X1[0], X1[1] } = { X1[1], X1[1] }
SHUFPD $2, X3, X2
SHUFPD $3, X3, X3
ADDPD X5, X0 // X0 += p_sum
ADDPD X1, X5 // p_sum += X1
ADDPD X5, X2
MOVUPS X0, (DI)(AX*8) // dst[i] = X0
MOVUPS X2, 16(DI)(AX*8)
ADDPD X3, X5
ADDQ $4, AX // i += 4
LOOP cs_loop // } while --CX > 0
// if BX == 0 { return }
CMPQ BX, $0
JE cs_end
cs_tail_start: // Reset loop registers
MOVQ BX, CX // Loop counter: CX = BX
cs_tail: // do {
ADDSD (SI)(AX*8), X5 // p_sum *= s[i]
MOVSD X5, (DI)(AX*8) // dst[i] = p_sum
INCQ AX // ++i
LOOP cs_tail // } while --CX > 0
cs_end:
MOVQ DI, ret_base+48(FP) // &ret = &dst
MOVQ dst_cap+16(FP), SI // cap(ret) = cap(dst)
MOVQ SI, ret_cap+64(FP)
RET
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