NEON向量化无符号字节乘积之和：（a [i] -int1）*（b [i] -int2）NEON vectorize sum of products of unsigned bytes: (a[i]-int1) * (b[i]-int2)

• `w`总是320（16/32的倍数）。
• `pa``pb`是16字节对齐的
• `ma``mb`是积极的。

`````` int whileInstruction (const unsigned char *pa,const unsigned char *pb,int ma,int mb,int w)
{
int sum=0;

do {
sum += ((*pa++)-ma)*((*pb++)-mb);

} while(--w);

return sum;
}
``````

``````int whileInstruction (const unsigned char *pa,const unsigned char *pb,int ma,int mb,int w)
{

asm volatile("lsr          %2, %2, #3      \n"
".loop:                       \n"
"vld4.8      {d0-d3}, [%1]!   \n"
"vld4.8      {d4-d7}, [%2]!   \n"
"# do the operation:     \n"
"vmlal.u8    q7, q7, q8       \n"
"# Sum the vector a save in sum (this is wrong):\n"
"subs        %2, %2, #1       \n" // Decrement iteration count
"bne         .loop            \n" // Repeat unil iteration count is not zero
:
: "r"(pa), "r"(pb), "r"(w),"r"(ma),"r"(mb),"r"(sum)
: "r4", "r5", "r6","r7","r8","r9"
);

return sum;
}
``````

2 个回复2

===============>>#1 票数：7 已采纳

``````#include <arm_neon.h>

int whileInstruction_neon(const unsigned char *pa, const unsigned char *pb, int ma, int mb, int w)
{
int sum = 0;

const int32x4_t vma = { ma, ma, ma, ma };
const int32x4_t vmb = { mb, mb, mb, mb };

int32x4_t vsumll = { 0 };
int32x4_t vsumlh = { 0 };
int32x4_t vsumhl = { 0 };
int32x4_t vsumhh = { 0 };
int32x4_t vsum;

int i;

for (i = 0; i <= (w - 16); i += 16)
{
uint8x16_t va = vld1q_u8(pa);   // load vector from pa
uint8x16_t vb = vld1q_u8(pb);   // load vector from pb

// unpack va into 4 vectors

int16x8_t val =  (int16x8_t)vmovl_u8(vget_low_u8(va));
int16x8_t vah =  (int16x8_t)vmovl_u8(vget_high_u8(va));
int32x4_t vall = vmovl_s16(vget_low_s16(val));
int32x4_t valh = vmovl_s16(vget_high_s16(val));
int32x4_t vahl = vmovl_s16(vget_low_s16(vah));
int32x4_t vahh = vmovl_s16(vget_high_s16(vah));

// subtract means

vall = vsubq_s32(vall, vma);
valh = vsubq_s32(valh, vma);
vahl = vsubq_s32(vahl, vma);
vahh = vsubq_s32(vahh, vma);

// unpack vb into 4 vectors

int16x8_t vbl =  (int16x8_t)vmovl_u8(vget_low_u8(vb));
int16x8_t vbh =  (int16x8_t)vmovl_u8(vget_high_u8(vb));
int32x4_t vbll = vmovl_s16(vget_low_s16(vbl));
int32x4_t vblh = vmovl_s16(vget_high_s16(vbl));
int32x4_t vbhl = vmovl_s16(vget_low_s16(vbh));
int32x4_t vbhh = vmovl_s16(vget_high_s16(vbh));

// subtract means

vbll = vsubq_s32(vbll, vmb);
vblh = vsubq_s32(vblh, vmb);
vbhl = vsubq_s32(vbhl, vmb);
vbhh = vsubq_s32(vbhh, vmb);

// update 4 partial sum of products vectors

vsumll = vmlaq_s32(vsumll, vall, vbll);
vsumlh = vmlaq_s32(vsumlh, valh, vblh);
vsumhl = vmlaq_s32(vsumhl, vahl, vbhl);
vsumhh = vmlaq_s32(vsumhh, vahh, vbhh);

pa += 16;
pb += 16;
}

// sum 4 partial sum of product vectors

// do scalar horizontal sum across final vector

sum = vgetq_lane_s32(vsum, 0);
sum += vgetq_lane_s32(vsum, 1);
sum += vgetq_lane_s32(vsum, 2);
sum += vgetq_lane_s32(vsum, 3);

// handle any residual non-multiple of 16 points

for ( ; i < w; ++i)
{
sum +=  (*pa++ - ma) * (*pb++ - mb);
}

return sum;
}
``````

===============>>#2 票数：1

``````int whileInstruction8Valors (const unsigned char *pa,const unsigned char *pb,int ma,int mb,int w)
{

int sum=0;
//int 32 bits /4 elementos?

const int32x4_t vma = { ma, ma, ma, ma };
const int32x4_t vmb = { mb, mb, mb, mb };

int32x4_t vsumll = { 0 };
int32x4_t vsumlh = { 0 };

int32x4_t vsum;

//char 8 bytes / 8 elementos
uint8x8_t  va2= vld1_u8(pa); // VLD1.8 {d0}, [r0]
uint8x8_t  vb2= vld1_u8(pb); // VLD1.8 {d0}, [r0]

//int 16 bytes /8 elementos
int16x8_t val =  (int16x8_t)vmovl_u8(va2);

//int 32 /4 elementos *2
int32x4_t vall = vmovl_s16(vget_low_s16(val));
int32x4_t valh = vmovl_s16(vget_high_s16(val));

// subtract means
vall = vsubq_s32(vall, vma);
valh = vsubq_s32(valh, vma);

//int 16 bytes /8 elementos
int16x8_t vbl2 =  (int16x8_t)vmovl_u8(vb2);

//int 32 /4 elementos *2
int32x4_t vbll = vmovl_s16(vget_low_s16(vbl2));
int32x4_t vblh = vmovl_s16(vget_high_s16(vbl2));

// subtract means

vbll = vsubq_s32(vbll, vmb);
vblh = vsubq_s32(vblh, vmb);

// update 4 partial sum of products vectors

vsumll = vmlaq_s32(vsumll, vall, vbll);
vsumlh = vmlaq_s32(vsumlh, valh, vblh);

// sum 4 partial sum of product vectors

// do scalar horizontal sum across final vector

sum = vgetq_lane_s32(vsum, 0);
sum += vgetq_lane_s32(vsum, 1);
sum += vgetq_lane_s32(vsum, 2);
sum += vgetq_lane_s32(vsum, 3);

return sum;
}
``````

1回复

1回复

1回复

1回复

2回复

1回复

1回复

1回复

1回复

1回复