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 AxpyInc(alpha float32, x, y []float32, n, incX, incY, ix, iy uintptr)
TEXT ·AxpyInc(SB), NOSPLIT, $0
    MOVQ  n+56(FP), CX      // CX = n
    CMPQ  CX, $0            // if n==0 { return }
    JLE   axpyi_end
    MOVQ  x_base+8(FP), SI  // SI = &x
    MOVQ  y_base+32(FP), DI // DI = &y
    MOVQ  ix+80(FP), R8     // R8 = ix
    MOVQ  iy+88(FP), R9     // R9 = iy
    LEAQ  (SI)(R8*4), SI    // SI = &(x[ix])
    LEAQ  (DI)(R9*4), DI    // DI = &(y[iy])
    MOVQ  DI, DX            // DX = DI   Read Pointer for y
    MOVQ  incX+64(FP), R8   // R8 = incX
    SHLQ  $2, R8            // R8 *= sizeof(float32)
    MOVQ  incY+72(FP), R9   // R9 = incY
    SHLQ  $2, R9            // R9 *= sizeof(float32)
    MOVSS alpha+0(FP), X0   // X0 = alpha
    MOVSS X0, X1            // X1 = X0  // for pipelining
    MOVQ  CX, BX
    ANDQ  $3, BX            // BX = n % 4
    SHRQ  $2, CX            // CX = floor( n / 4 )
    JZ    axpyi_tail_start  // if CX == 0 { goto axpyi_tail_start }

axpyi_loop: // Loop unrolled 4x   do {
    MOVSS (SI), X2       // X_i = x[i]
    MOVSS (SI)(R8*1), X3
    LEAQ  (SI)(R8*2), SI // SI = &(SI[incX*2])
    MOVSS (SI), X4
    MOVSS (SI)(R8*1), X5
    MULSS X1, X2         // X_i *= a
    MULSS X0, X3
    MULSS X1, X4
    MULSS X0, X5
    ADDSS (DX), X2       // X_i += y[i]
    ADDSS (DX)(R9*1), X3
    LEAQ  (DX)(R9*2), DX // DX = &(DX[incY*2])
    ADDSS (DX), X4
    ADDSS (DX)(R9*1), X5
    MOVSS X2, (DI)       // y[i] = X_i
    MOVSS X3, (DI)(R9*1)
    LEAQ  (DI)(R9*2), DI // DI = &(DI[incY*2])
    MOVSS X4, (DI)
    MOVSS X5, (DI)(R9*1)
    LEAQ  (SI)(R8*2), SI // SI = &(SI[incX*2])  // Increment addresses
    LEAQ  (DX)(R9*2), DX // DX = &(DX[incY*2])
    LEAQ  (DI)(R9*2), DI // DI = &(DI[incY*2])
    LOOP  axpyi_loop     // } while --CX > 0
    CMPQ  BX, $0         // if BX == 0 { return }
    JE    axpyi_end

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

axpyi_tail: // do {
    MOVSS (SI), X2   // X2 = x[i]
    MULSS X1, X2     // X2 *= a
    ADDSS (DI), X2   // X2 += y[i]
    MOVSS X2, (DI)   // y[i] = X2
    ADDQ  R8, SI     // SI = &(SI[incX])
    ADDQ  R9, DI     // DI = &(DI[incY])
    LOOP  axpyi_tail // } while --CX > 0

axpyi_end:
    RET