Revision 4bdc44c7 libswscale/internal_bfin.S
libswscale/internal_bfin.S  

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/* 
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YUV420 to RGB565 conversion. This routine takes a YUV 420 planar macroblock


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and converts it to RGB565. R:5 bits, G:6 bits, B:5 bits.. packed into shorts


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YUV420 to RGB565 conversion. This routine takes a YUV 420 planar macroblock 

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and converts it to RGB565. R:5 bits, G:6 bits, B:5 bits.. packed into shorts 

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The following calculation is used for the conversion:


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The following calculation is used for the conversion: 

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r = clipz((yoy)*cy + crv*(v128))


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g = clipz((yoy)*cy + cgv*(v128) + cgu*(u128))


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b = clipz((yoy)*cy + cbu*(u128))


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r = clipz((yoy)*cy + crv*(v128)) 

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g = clipz((yoy)*cy + cgv*(v128) + cgu*(u128)) 

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b = clipz((yoy)*cy + cbu*(u128)) 

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y,u,v are pre scaled by a factor of 4 i.e. left shifted to gain precision.


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y,u,v are pre scaled by a factor of 4 i.e. left shifted to gain precision. 

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New factorization to eliminate the truncation error which was


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occuring due to the byteop3p.


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New factorization to eliminate the truncation error which was 

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occuring due to the byteop3p. 

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1) use the bytop16m to subtract quad bytes we use this in U8 this


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then so the offsets need to be renormalized to 8bits.


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1) use the bytop16m to subtract quad bytes we use this in U8 this 

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then so the offsets need to be renormalized to 8bits. 

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2) scale operands up by a factor of 4 not 8 because Blackfin


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multiplies include a shift.


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2) scale operands up by a factor of 4 not 8 because Blackfin 

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multiplies include a shift. 

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3) compute into the accumulators cy*yx0, cy*yx1


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3) compute into the accumulators cy*yx0, cy*yx1 

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4) compute each of the linear equations


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r = clipz((yoy)*cy + crv*(v128))


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4) compute each of the linear equations 

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r = clipz((y  oy) * cy + crv * (v  128))


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g = clipz((yoy)*cy + cgv*(v128) + cgu*(u128))


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g = clipz((y  oy) * cy + cgv * (v  128) + cgu * (u  128))


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b = clipz((yoy)*cy + cbu*(u128))


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b = clipz((y  oy) * cy + cbu * (u  128))


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reuse of the accumulators requires that we actually multiply


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twice once with addition and the second time with a subtaction.


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reuse of the accumulators requires that we actually multiply 

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twice once with addition and the second time with a subtaction. 

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because of this we need to compute the equations in the order R B


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then G saving the writes for B in the case of 24/32 bit color


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formats.


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because of this we need to compute the equations in the order R B 

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then G saving the writes for B in the case of 24/32 bit color 

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formats. 

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api: yuv2rgb_kind (uint8_t *Y, uint8_t *U, uint8_t *V, int *out,


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int dW, uint32_t *coeffs);


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api: yuv2rgb_kind (uint8_t *Y, uint8_t *U, uint8_t *V, int *out, 

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int dW, uint32_t *coeffs); 

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A B


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i2 = cb i3 = cr


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i1 = coeff i0 = y


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A B 

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i2 = cb i3 = cr 

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i1 = coeff i0 = y 

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Where coeffs have the following layout in memory.


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Where coeffs have the following layout in memory. 

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uint32_t oy,oc,zero,cy,crv,rmask,cbu,bmask,cgu,cgv;


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uint32_t oy,oc,zero,cy,crv,rmask,cbu,bmask,cgu,cgv; 

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coeffs is a pointer to oy.


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coeffs is a pointer to oy. 

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the {rgb} masks are only utilized by the 565 packing algorithm. Note the data


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replication is used to simplify the internal algorithms for the dual mac architecture


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of BlackFin.


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the {rgb} masks are only utilized by the 565 packing algorithm. Note the data 

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replication is used to simplify the internal algorithms for the dual mac architecture 

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of BlackFin. 

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All routines are exported with _ff_bfin_ as a symbol prefix


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All routines are exported with _ff_bfin_ as a symbol prefix 

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rough performance gain compared against O3:


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rough performance gain compared against O3: 

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2779809/1484290 187.28% 

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which translates to ~33c/pel to ~57c/pel for the reference vs 17.5 

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c/pel for the optimized implementations. Not sure why there is such a 

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huge variation on the reference codes on Blackfin I guess it must have 

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to do with the memory system. 

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2779809/1484290 187.28% 

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which translates to ~33c/pel to ~57c/pel for the reference vs 17.5 

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c/pel for the optimized implementations. Not sure why there is such a 

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huge variation on the reference codes on Blackfin I guess it must have 

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to do with the memory system. 

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*/ 
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#define mL3 .text 
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