我在前面的两篇随笔中，写到了YUV与RGB的互转公式，也写了一些SSE指令学习的常用指令。因为接下来我决定暂停对SSE指令的简单翻译，而要把他用到实践中去。因此会贴上大篇幅的看起来让人头晕目眩的代码，不过我会尽力写好注释，以免大家看起来比较费劲。
既然说SSE能够对重复大量相同运算的数据在运算效率上有很大的提升，那就需要与高级语言（因为我常用的是C++,所以就采用C++语言）做一个对比。
在此之前，我要提前做一下说明，YUV我采用的4:2:2的压缩方式，也就是两个Y分量公用一组UV分量，并且每个YUV分量分别占10bit,但是考虑的内存对齐，YUV分量其实分别占用2个字节，并且我在这里使用的公式BT709的数字RGB与数字YUV的转换公式。
如果不清楚转换公式，可以转到我的一篇关于YUV与RGB互转的公式总结的随笔。
http://www.cnblogs.com/zhengjianhong/p/7872459.html
C++代码如下：
void RGB2YUV(OUT ushort &Y, OUT ushort &U, OUT ushort &V, IN const BYTE r, IN const BYTE g, IN const BYTE b){
Y = ushort(16 + 0.183 * r + 0.614 * g + 0.062 * b + 0.5);
U = ushort(128 - 0.101 * r - 0.339 * g + 0.439 * b + 0.5);
V = ushort(128 + 0.439 * r - 0.399 * g - 0.040* b + 0.5);
}bool RGB2YUV422_10BIT_CPLUSPLUS(OUT void* pYUV, IN void *pRGB, int nPixelCount, bool bAlpha)
{
if(pYUV == NULL || pRGB == NULL || nPixelCount <= 0)
return false;
// RGB 到 YUV422 10bit的转换
BYTE *pRGBByte = (BYTE *)pRGB;
ushort *pYUVShort = (ushort *)pYUV;
int nBitCount = 3;
if(bAlpha)
nBitCount = 4;
for(int i = 0; i < nPixelCount; i += 2)
{
// 第一个像素
ushort y, u, v; pRGBByte += nBitCount; RGB2YUV(y, u, v, *(pRGBByte), *(pRGBByte + 1), *(pRGBByte + 2));
*(pYUVShort + 2 * i) = y;
*(pYUVShort + 2 * i + 1) = u;
*(pYUVShort + 2 * i + 3) = v;
// 第二个像素 pRGBByte += nBitCount; RGB2YUV(y, u, v, *(pRGBByte), *(pRGBByte + nBitCount * (i + 1) + 1), *(pRGBByte + nBitCount * (i + 1) + 2));*(pYUVShort + 2 * i + 2) = y; }return true;}
SSE代码如下：
// 在这里我考虑在精度允许的情况下，综合考虑在不产生进位的情况下对RGB转YUV的因子做了放大处理（放大256倍），以消除浮点运算，提高指令的执行效率。
实现思路：一条跳转指令完成8个像素的处理，先将8个像素的RGB分量分别用一个128位寄存器来存储,RGB的每个分量占2个字节, 并且用128位来存储每个转换因子，每个因子一样占2个字节。简单点说就是
(R0R1 R2R3 R4R5 R6R7) * (YrYr YrYr YrYr YrYr) 这样就计算出了构成Y的R部分简称YR，以此类推，分别计算出YG, YB,然后在将YR，YG，YB做加法运算，最终计算出Y的结果。
// 因子的顺序为YrYg YbUr UgUb VgVb // Vr = Ub__declspec(align(16)) short dwRGB2YCbCrCoefFR256[8] = {77, 150, 29, -43, -85, 128, -107, -21}; // Full Range
__declspec(align(16)) short dwRGB2YCbCrCoefHD256[8] = {47, 157, 16, -26, -87, 112, -102, -10};
__declspec(align(16)) short dwRGB2YCbCrCoefSD256[8] = {66, 129, 25, -38, -74, 112, -94, -18};bool RGBA2YUV422_10BIT_SSE_Nofloat(OUT void* pYUV, IN void *pRGB, int nPixelCount, short* dwRGBA2YCbCrCoef)
{
if(pYUV == NULL || pRGB == NULL || nPixelCount <= 0)
return false;
int n32 = nPixelCount / 8;
int m32 = nPixelCount % 8;
BYTE *pByte = (BYTE *)pRGB;
ushort *pYuvShort = (ushort *)pYUV;
__m128i _m128i;
__asm
{
mov esi, pByte;
mov edi, pYuvShort;
mov ecx, n32;
mov edx, m32;
mov eax, dwRGBA2YCbCrCoef;
movaps xmm7, [eax];
movaps _m128i, xmm7;
prefetchnta [esi];
test ecx, ecx;
jz loop_m32;
loop_32:
prefetchnta [esi + 32]; // prefetchnta指令，将内存数据加载到缓存中，提高指令的数据命中率
movups xmm0, [esi]; // A3B3G3R3 A2B2G2R2 A1B1G1R1 A0B0G0R0
movups xmm1, [esi + 16]; // A7B7G7R7 A6B6G6R6 A5B5G5R5 A4B4G4R4
pand xmm0, dwMaskA; // 0B3G3R3 0B2G2R2 0B1G1R1 0B0G0R0
pand xmm1, dwMaskA; // 0B7G7R7 0B6G6R6 0B5G5R5 0B4G4R4
movaps xmm2, xmm0;
movaps xmm3, xmm1;
pand xmm2, dwMaskR; // 000R3 000R2 000R1 000R0
pand xmm3, dwMaskR; // 000R7 000R6 000R5 000R4
packssdw xmm2, xmm3; // 0R70R6 0R50R4 0R30R2 0R10R0
movaps xmm3, xmm0;
movaps xmm4, xmm1;
psrld xmm3, 8;
psrld xmm4, 8;
pand xmm3, dwMaskR; // 000G3 000G2 000G1 000G0
pand xmm4, dwMaskR; // 000G7 000G6 000G5 000G4
packssdw xmm3, xmm4; // 0G70G6 0G50G4 0G30G2 0G10G0
movaps xmm4, xmm0;
movaps xmm5, xmm1;
psrld xmm4, 16;
psrld xmm5, 16;
pand xmm4, dwMaskR; // 000B3 000B2 000B1 000B0
pand xmm5, dwMaskR; // 000B7 000B6 000B5 000B4
packssdw xmm4, xmm5; // 0B70B6 0B50B4 0B30B2 0B10B0
movaps xmm0, xmm7; // VbVg UbUg UrYb YgYr // 系数
pshuflw xmm0, xmm0, 0x00; // VbVg UbUg YrYr YrYr
shufps xmm0, xmm0, 0x00; // YrYr YrYr YrYr YrYr
movups _m128i, xmm0;
movaps xmm1, xmm2;
pmullw xmm1, xmm0; // YR7YR6 YR5YR4 YR3Yr2 YR1YR0
movups _m128i, xmm1;
movaps xmm0, xmm7;
pshuflw xmm0, xmm0, 0x05; // VbVg UbUg YrYr YgYg
shufps xmm0, xmm0, 0x00; // YgYg YgYg YgYg YgYg
movups _m128i, xmm0;
movaps xmm5, xmm3;
pmullw xmm5, xmm0; // YG7YG6 YG5YG4 YG3YG2 YG1YG0
paddw xmm1, xmm5; // YR+YG
movups _m128i, xmm1;
movaps xmm0, xmm7;
pshuflw xmm0, xmm0, 0x0a; // VbVg UbUg YrYr YbYb
shufps xmm0, xmm0, 0x00; // YbYb YbYb YbYb YbYb
movups _m128i, xmm0;
movaps xmm5, xmm4;
pmullw xmm5, xmm0; // YB7YB6 YB5YB4 YB3YB2 YB1YB0
paddw xmm1, xmm5; // YR+YG+YB
movups _m128i, xmm1;
paddw xmm1, dwAdjust128;
psrlw xmm1, 8; // Y7Y6 Y5Y4 Y3Y2 Y1Y0
movups _m128i, xmm1;
movaps xmm0, xmm7;
pshuflw xmm0, xmm0, 0x0f; // VbVg UbUg YrYr UrUr;
shufps xmm0, xmm0, 0x00; // UrUr UrUr UrUr UrUr
movups _m128i, xmm0;
movaps xmm5, xmm2;
pmullw xmm5, xmm0; // UR7UR6 UR5UR4 UR3UR2 UR1UR0
movups _m128i, xmm5;
movaps xmm0, xmm7;
pshufhw xmm0, xmm0, 0x00; // UgUg UgUg UrYb YgYr
shufps xmm0, xmm0, 0xaa; // UgUg UgUg UgUg UgUg
movups _m128i, xmm0;
movaps xmm6, xmm3;
pmullw xmm6, xmm0; // UG7UG6 UG5UG4 UG3UG2 UG1UG0
movups _m128i, xmm6;
paddw xmm5, xmm6; // UR+UG
movups _m128i, xmm5;
movaps xmm0, xmm7;
pshufhw xmm0, xmm0, 0x05; // UgUg UbUb UrYb YgYr
shufps xmm0, xmm0, 0xaa; // UbUb UbUb UbUb UbUb
movups _m128i, xmm0;
movaps xmm6, xmm4;
pmullw xmm6, xmm0; // UB7UB6 UB5UB4 UB3UB2 UB1UB0
movups _m128i, xmm6;
paddw xmm5, xmm6; // UR + UG + UB
movups _m128i, xmm5;
paddw xmm5, dwAdjust;
paddw xmm5, dwAdjust128;
movups _m128i, xmm5;
psrlw xmm5, 8; // U7U6 U5U4 U3U2 U1U0
movups _m128i, xmm5;
pmullw xmm2, xmm0; // VR7VR6 VR5VR4 VR3VR2 VR1VR0
movaps xmm0, xmm7;
pshufhw xmm0, xmm0, 0xaa; // VgVg VgVg UrYb YgYr
shufps xmm0, xmm0, 0xaa; // VgVg VgVg VgVg VgVg
pmullw xmm3, xmm0; // VG7VG6 VG5VG4 VG3VG2 VG1VG0
paddw xmm2, xmm3; // VR + VG
movaps xmm0, xmm7;
pshufhw xmm0, xmm0, 0xff; // VbVb VbVb UrYb YgYr
shufps xmm0, xmm0, 0xaa; // VbVb VbVb VbVb VbVb
pmullw xmm4, xmm0; // VB7VB6 VB5VB4 VB3VB2 VB1VB0
paddw xmm2, xmm4; // VR + VG + VB
paddw xmm2, dwAdjust;
paddw xmm2, dwAdjust128;
psrlw xmm2, 8; // V7V6 V5V4 V3V2 V1V0
movaps xmm4, xmm5;
punpcklwd xmm4, xmm2; // V3U3 V2U2 V1U1 V0U0
punpckhwd xmm5, xmm2; // V7U7 V6U6 V5U5 V4U4
shufps xmm4, xmm5, 0x88; // V6U6 V4U4 V2U2 V0U0
movaps xmm3, xmm1;
punpcklwd xmm3, xmm4; // V2Y3 U2Y2 V0Y1 U0Y0
punpckhwd xmm1, xmm4; // V6Y7 U6Y6 V4Y5 U4Y4
movups [edi], xmm3;
movups [edi + 16], xmm1;
add edi, 32;
add esi, 32;
dec ecx;
jnz loop_32;
loop_m32:
test edx, edx;
jz loop_exit;
cmp edx, 4;
jl loop_2pixel;
movups xmm0, [esi]; //A3B3G3R3 A2B2G2R2 A1B1G1R1 A0B0G0R0
pand xmm0, dwMaskA; // 0B3G3R3 0B2G2R2 0B1G1R1 0B0G0R0
movaps xmm1, xmm0;
pand xmm1, dwMaskR; // 000R3 000R2 000R1 000R0
pshuflw xmm1, xmm1, 0xd8; // 000R3 000R2 0000 0R10R0
pshufhw xmm1, xmm1, 0xd8; // 0000 0R30R2 0000 0R10R0
shufps xmm1, xmm1, 0xd8; // 0000 0000 0R30R2 0R10R0
movaps xmm2, xmm0;
psrld xmm2, 8;
pand xmm2, dwMaskR;
pshuflw xmm2, xmm2, 0xd8;
pshufhw xmm2, xmm2, 0xd8;
shufps xmm2, xmm2, 0xd8; // 0000 0000 0G30G2 0G10G0
movaps xmm3, xmm0;
psrld xmm3, 16;
pand xmm3, dwMaskR;
pshuflw xmm3, xmm3, 0xd8;
pshufhw xmm3, xmm3, 0xd8;
shufps xmm3, xmm3, 0xd8; // 0000 0000 0B30B2 0B10B0
movaps xmm0, xmm7; // VbVg UbUg UrYb YgYr
pshuflw xmm0, xmm0, 0x00; // VbVg UbUg YrYr YrYr
movups xmm4, xmm1;
pmullw xmm4, xmm0; // 0000 0000 YR3YR2 YR1YR0
movaps xmm0, xmm7;
pshuflw xmm0, xmm0, 0x55; // VbVg UbUg YgYg YgYg
movaps xmm5, xmm2;
pmullw xmm5, xmm0; // 0000 0000 YG3YG2 YG1YG0
paddw xmm4, xmm5; // 00 00 (YR+YG)(YR+YG) (YR+YG)(YR+YG)
movaps xmm0, xmm7;
pshuflw xmm0, xmm0, 0xaa; // VbVg UbUg YbYb YbYb
movups xmm5, xmm3;
pmullw xmm5, xmm0; // 00 00 YB3YB2 YB1YB0
paddw xmm4, xmm5; // 00 00 Y3Y2 Y1Y0
psrlw xmm4, 8;
movaps xmm0, xmm7;
pshuflw xmm0 ,xmm0, 0xff; // VbVb UbUg UrUr UrUr;
movups xmm5, xmm1;
pmullw xmm5, xmm0; // 00 00 UR3UR2 UR1UR0
movaps xmm0, xmm7;
pshufhw xmm0, xmm0, 0x00; // UgUg UgUg UrYb YgYr
shufps xmm0, xmm0, 0xee; // UgUg UgUg UgUg UgUg
movups xmm6, xmm2;
pmullw xmm6, xmm0; // 00 00 UG3UG2 UG1UG0
paddw xmm5, xmm6; // 00 00 U3'U2' U1'U0'
movaps xmm0, xmm7;
pshufhw xmm0, xmm0, 0x55;
shufps xmm0, xmm0, 0xee; // UbUb UbUb UbUb UbUb
movups xmm6, xmm3;
pmullw xmm6, xmm0; // 00 00 UB3UB2 UB1UB0
paddw xmm5, xmm6; // 00 00 U3U2 U1U0
psrlw xmm5, 8;
paddw xmm5, dwAdjust;
pmullw xmm1, xmm0; // 00 00 VR3VR2 VR1VR0
movaps xmm0, xmm7;
pshufhw xmm0, xmm0, 0xaa; // VgVg VgVg UrYb YgYr
shufps xmm0, xmm0, 0xee; // VgVg VgVg VgVg VgVg;
pmullw xmm2, xmm0; // 00 00 VG3VG2 VG1VG0
paddw xmm1, xmm2; // 00 00 U3'U2' U1'U0'
movaps xmm0, xmm7;
pshufhw xmm0, xmm0, 0xff; // VbVb VbVb UrYb YgYr
shufps xmm0, xmm0, 0xee; // VbVb VbVb VbVb VbVb
pmullw xmm3, xmm0; // 00 00 VB3VB2 VB1VB0
paddw xmm1, xmm3; // 00 00 V3V2 V1V0
psrlw xmm1, 8;
paddw xmm1, dwAdjust;
punpcklwd xmm5, xmm1; // V3U3 V2U2 V1U1 V0U0
shufps xmm5, xmm5, 0xd8; // V3U3 V1U1 V2U2 V0U0
punpcklwd xmm4, xmm5; // V2Y3 U2Y2 V0Y1 U0Y0
movups [edi], xmm4;
add esi, 16;
add edi, 16;
sub edx, 4;
jnz loop_m32;
loop_2pixel:
test edx, edx;
jz loop_exit;
cmp edx, 2;
jl loop_spixel;
movups xmm0, [esi];
pand xmm0, dwMaskA; // 0000 0000 0B1G1R1 0B0G0R0
movups xmm1, xmm0;
pand xmm1, dwMaskR; // 0000 0000 000R1 000R0
pshuflw xmm1, xmm1, 0xd8; // 0000 0000 0000 0R10R0
movups xmm2, xmm0;
psrld xmm2, 8;
pand xmm2, dwMaskR;
pshuflw xmm2, xmm2, 0xd8; // 0000 0000 0000 0G10G0
movups xmm3, xmm0;
psrld xmm3, 16;
pand xmm3, dwMaskR;
pshuflw xmm3, xmm3, 0xd8; // 0000 0000 0000 0B10B0
movups xmm0, xmm7; // VbVg UbUg UrYb YgYr
pshuflw xmm0, xmm0, 0x00; // VbVg UbUg YrYr YrYr;
movups xmm4, xmm1;
pmullw xmm4, xmm0; // 00 00 00 YR1YR0
movups xmm0, xmm7;
pshuflw xmm0, xmm0, 0x55;
movups xmm5, xmm2;
pmullw xmm5, xmm0; // 00 00 00 YG1YG0
paddw xmm4, xmm5; // 00 00 00 Y1'Y0'
movups xmm0, xmm7;
pshuflw xmm0, xmm0, 0xaa;
movups xmm5, xmm3;
pmullw xmm5, xmm0; // 00 00 00 YB1YB0
paddw xmm4, xmm5; // 00 00 00 Y1Y0
psrlw xmm4, 8;
movups xmm0, xmm7;
pshuflw xmm0, xmm0, 0xff;
movups xmm5, xmm1;
pmullw xmm5, xmm0; // 00 00 00 UR1UR0
movups xmm0, xmm7;
pshufhw xmm0, xmm0, 0x00; // UgUg UgUg .. ..
shufps xmm0, xmm0, 0xee; // .. .. UgUg UgUg
movups xmm6, xmm2;
pmullw xmm6, xmm0; // 00 00 00 UG1 UG0;
paddw xmm5, xmm6;
movups xmm0, xmm7;
pshufhw xmm0, xmm0, 0x55;
shufps xmm0, xmm0, 0xee;
movups xmm6, xmm3;
pmullw xmm6, xmm0; // 00 00 00 UB1UB0
paddw xmm5, xmm6; // 00 00 00 U1U0
psrlw xmm5, 8;
psrlw xmm5, dwAdjust;
pmullw xmm1, xmm0; // 00 00 00 VR1VR0
movups xmm0, xmm7;
pshufhw xmm0, xmm0, 0xaa;
shufps xmm0, xmm0, 0xee;
pmullw xmm2, xmm0; // 00 00 00 VG1VG0
paddw xmm1, xmm2;
movups xmm0, xmm7;
pshufhw xmm0, xmm0, 0xff;
shufps xmm0, xmm0, 0xee;
pmullw xmm3, xmm0; // 00 00 00 VB1VB0
paddw xmm1, xmm3; // 00 00 00 V1V0;
punpcklwd xmm5, xmm1; // 00 00 V1U1 V0U0
punpcklwd xmm4, xmm5; // V10 U10 V0Y1 U0Y0
movlps [edi], xmm4;
add edi, 8;
add esi, 8;
sub edx, 2;
jnz loop_2pixel;
loop_spixel:
loop_exit:
}
return true;
}
下面附上两种转换对比的贴图：
前面代表debug下的执行截图，后面表示Releas下的执行截图。总体而言SSE指令优化之后的代码执行效率比较稳定，而Release开启优化之后的C++代码提升比较明显，但是仍然没有SSE指令的效率高。
至于YUV转RGB的指令优化，有兴趣的同学，可以自己尝试写一下。
在这里，我也是刚刚入门SSE指令优化，如果有同学发现问题，还希望可以指出来。
原文链接: https://www.cnblogs.com/zhengjianhong/p/7883945.html
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