nlpodyssey/spago

// 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"

// func Div(dst, s []float64)
TEXT ·Div(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
    CMPQ    CX, $0             // if CX == 0 { return }
    JE      div_end
    XORQ    AX, AX             // i = 0
    MOVQ    SI, BX
    ANDQ    $15, BX            // BX = &s & 15
    JZ      div_no_trim        // if BX == 0 { goto div_no_trim }

    // Align on 16-bit boundary
    MOVSD (DI)(AX*8), X0 // X0 = dst[i]
    DIVSD (SI)(AX*8), X0 // X0 /= s[i]
    MOVSD X0, (DI)(AX*8) // dst[i] = X0
    INCQ  AX             // ++i
    DECQ  CX             // --CX
    JZ    div_end        // if CX == 0 { return }

div_no_trim:
    MOVQ CX, BX
    ANDQ $7, BX         // BX = len(dst) % 8
    SHRQ $3, CX         // CX = floor( len(dst) / 8 )
    JZ   div_tail_start // if CX == 0 { goto div_tail_start }

div_loop: // Loop unrolled 8x   do {
    MOVUPS (DI)(AX*8), X0   // X0 = dst[i:i+1]
    MOVUPS 16(DI)(AX*8), X1
    MOVUPS 32(DI)(AX*8), X2
    MOVUPS 48(DI)(AX*8), X3
    DIVPD  (SI)(AX*8), X0   // X0 /= s[i:i+1]
    DIVPD  16(SI)(AX*8), X1
    DIVPD  32(SI)(AX*8), X2
    DIVPD  48(SI)(AX*8), X3
    MOVUPS X0, (DI)(AX*8)   // dst[i] = X0
    MOVUPS X1, 16(DI)(AX*8)
    MOVUPS X2, 32(DI)(AX*8)
    MOVUPS X3, 48(DI)(AX*8)
    ADDQ   $8, AX           // i += 8
    LOOP   div_loop         // } while --CX > 0
    CMPQ   BX, $0           // if BX == 0 { return }
    JE     div_end

div_tail_start: // Reset loop registers
    MOVQ BX, CX // Loop counter: CX = BX

div_tail: // do {
    MOVSD (DI)(AX*8), X0 // X0 = dst[i]
    DIVSD (SI)(AX*8), X0 // X0 /= s[i]
    MOVSD X0, (DI)(AX*8) // dst[i] = X0
    INCQ  AX             // ++i
    LOOP  div_tail       // } while --CX > 0

div_end:
    RET