//go:build amd64
// +build amd64

#include "textflag.h"

// func siluAVX2Asm(x *float32, n int)
TEXT ·siluAVX2Asm(SB), NOSPLIT, $0-16
	// Load args
	MOVQ x+0(FP), DI
	MOVQ n+8(FP), CX

	CMPQ CX, $0
	JLE done

	// Broadcast constants
	VBROADCASTSS ·expHi(SB), Y14
	VBROADCASTSS ·expLo(SB), Y13
	VBROADCASTSS ·log2EF(SB), Y12
	VBROADCASTSS ·halfConst(SB), Y11
	VBROADCASTSS ·expC1(SB), Y10
	VBROADCASTSS ·expC2(SB), Y9
	VBROADCASTSS ·oneConst(SB), Y8
	VPBROADCASTD ·signMaskConst(SB), Y15

loop:
	CMPQ CX, $8
	JL done

	VMOVUPS (DI), Y0         // original x
	VMOVAPS Y0, Y1           // copy for neg
	VXORPS Y15, Y1, Y1       // y1 = -x

	VMINPS Y14, Y1, Y1       // clamp hi
	VMAXPS Y13, Y1, Y1       // clamp lo

	VMULPS Y12, Y1, Y2       // y2 = x * log2e
	VADDPS Y11, Y2, Y2       // +0.5
	VROUNDPS $1, Y2, Y2      // floor

	VCVTPS2DQ Y2, Y6         // integer exponent
	VCVTDQ2PS Y6, Y5         // fx as float

	VMULPS Y10, Y5, Y3       // fx * C1
	VSUBPS Y3, Y1, Y1
	VMULPS Y9, Y5, Y3        // fx * C2
	VSUBPS Y3, Y1, Y1

	VMULPS Y1, Y1, Y3        // z = x*x

	VBROADCASTSS ·polyP0(SB), Y4
	VMULPS Y1, Y4, Y4
	VBROADCASTSS ·polyP1(SB), Y5
	VADDPS Y5, Y4, Y4
	VMULPS Y1, Y4, Y4
	VBROADCASTSS ·polyP2(SB), Y5
	VADDPS Y5, Y4, Y4
	VMULPS Y1, Y4, Y4
	VBROADCASTSS ·polyP3(SB), Y5
	VADDPS Y5, Y4, Y4
	VMULPS Y1, Y4, Y4
	VBROADCASTSS ·polyP4(SB), Y5
	VADDPS Y5, Y4, Y4
	VMULPS Y1, Y4, Y4
	VBROADCASTSS ·polyP5(SB), Y5
	VADDPS Y5, Y4, Y4

	VMULPS Y3, Y4, Y4        // y *= z
	VADDPS Y1, Y4, Y4        // y += x
	VADDPS Y8, Y4, Y4        // y += 1

	VPBROADCASTD ·expBiasConst(SB), Y5
	VPADDD Y5, Y6, Y6
	VPSLLD $23, Y6, Y6
	VMULPS Y6, Y4, Y4        // exp(-x)

	VADDPS Y8, Y4, Y3        // denom = 1 + exp(-x)
	VDIVPS Y3, Y8, Y3        // 1 / denom
	VMULPS Y0, Y3, Y0        // x * sigmoid(x)
	VMOVUPS Y0, (DI)

	ADDQ $32, DI
	SUBQ $8, CX
	JMP loop

done:
	RET

// Constants (single-float broadcast)
DATA ·expHi+0(SB)/4, $0x42b0c0a5
GLOBL ·expHi(SB), RODATA, $4

DATA ·expLo+0(SB)/4, $0xc2b0c0a5
GLOBL ·expLo(SB), RODATA, $4

DATA ·log2EF+0(SB)/4, $0x3fb8aa3b
GLOBL ·log2EF(SB), RODATA, $4

DATA ·halfConst+0(SB)/4, $0x3f000000
GLOBL ·halfConst(SB), RODATA, $4

DATA ·expC1+0(SB)/4, $0x3f318000
GLOBL ·expC1(SB), RODATA, $4

DATA ·expC2+0(SB)/4, $0xb95e8083
GLOBL ·expC2(SB), RODATA, $4

DATA ·polyP0+0(SB)/4, $0x39506967
GLOBL ·polyP0(SB), RODATA, $4

DATA ·polyP1+0(SB)/4, $0x3ab743ce
GLOBL ·polyP1(SB), RODATA, $4

DATA ·polyP2+0(SB)/4, $0x3c088908
GLOBL ·polyP2(SB), RODATA, $4

DATA ·polyP3+0(SB)/4, $0x3d2aa9c1
GLOBL ·polyP3(SB), RODATA, $4

DATA ·polyP4+0(SB)/4, $0x3e2aaaaa
GLOBL ·polyP4(SB), RODATA, $4

DATA ·polyP5+0(SB)/4, $0x3f000000
GLOBL ·polyP5(SB), RODATA, $4

DATA ·oneConst+0(SB)/4, $0x3f800000
GLOBL ·oneConst(SB), RODATA, $4

DATA ·signMaskConst+0(SB)/4, $0x80000000
GLOBL ·signMaskConst(SB), RODATA, $4

DATA ·expBiasConst+0(SB)/4, $0x0000007f
GLOBL ·expBiasConst(SB), RODATA, $4