* Copyright (C) 2007 Marc Hoffman <marc.hoffman@analog.com>
* April 20, 2007
*
- * Blackfin Video Color Space Converters Operations
- * convert I420 YV12 to RGB in various formats,
+ * Blackfin video color space converter operations
+ * convert I420 YV12 to RGB in various formats
*
* This file is part of FFmpeg.
*
/*
- YUV420 to RGB565 conversion. This routine takes a YUV 420 planar macroblock
- and converts it to RGB565. R:5 bits, G:6 bits, B:5 bits.. packed into shorts
+YUV420 to RGB565 conversion. This routine takes a YUV 420 planar macroblock
+and converts it to RGB565. R:5 bits, G:6 bits, B:5 bits.. packed into shorts.
- The following calculation is used for the conversion:
+The following calculation is used for the conversion:
- r = clipz((y-oy)*cy + crv*(v-128))
- g = clipz((y-oy)*cy + cgv*(v-128) + cgu*(u-128))
- b = clipz((y-oy)*cy + cbu*(u-128))
+ r = clipz((y-oy)*cy + crv*(v-128))
+ g = clipz((y-oy)*cy + cgv*(v-128) + cgu*(u-128))
+ b = clipz((y-oy)*cy + cbu*(u-128))
- y,u,v are pre scaled by a factor of 4 i.e. left shifted to gain precision.
+y,u,v are prescaled by a factor of 4 i.e. left-shifted to gain precision.
- New factorization to elliminate the truncation error which was
- occuring due to the byteop3p.
+New factorization to eliminate the truncation error which was
+occurring due to the byteop3p.
- 1) use the bytop16m to subtract quad bytes we use this in U8 this
- then so the offsets need to be renormalized to 8bits.
+1) Use the bytop16m to subtract quad bytes we use this in U8 this
+ then so the offsets need to be renormalized to 8bits.
- 2) scale operands up by a factor of 4 not 8 because Blackfin
- multiplies include a shift.
+2) Scale operands up by a factor of 4 not 8 because Blackfin
+ multiplies include a shift.
- 3) compute into the accumulators cy*yx0, cy*yx1
+3) Compute into the accumulators cy*yx0, cy*yx1.
- 4) compute each of the linear equations
- r = clipz((y-oy)*cy + crv*(v-128))
+4) Compute each of the linear equations:
+ r = clipz((y - oy) * cy + crv * (v - 128))
- g = clipz((y-oy)*cy + cgv*(v-128) + cgu*(u-128))
+ g = clipz((y - oy) * cy + cgv * (v - 128) + cgu * (u - 128))
- b = clipz((y-oy)*cy + cbu*(u-128))
+ b = clipz((y - oy) * cy + cbu * (u - 128))
- reuse of the accumulators requires that we actually multiply
- twice once with addition and the second time with a subtaction.
+ Reuse of the accumulators requires that we actually multiply
+ twice once with addition and the second time with a subtraction.
- because of this we need to compute the equations in the order R B
- then G saving the writes for B in the case of 24/32 bit color
- formats.
+ Because of this we need to compute the equations in the order R B
+ then G saving the writes for B in the case of 24/32 bit color
+ formats.
- api: yuv2rgb_kind (uint8_t *Y, uint8_t *U, uint8_t *V, int *out,
- int dW, uint32_t *coeffs);
+ API: yuv2rgb_kind (uint8_t *Y, uint8_t *U, uint8_t *V, int *out,
+ int dW, uint32_t *coeffs);
- A B
- --- ---
- i2 = cb i3 = cr
- i1 = coeff i0 = y
+ A B
+ --- ---
+ i2 = cb i3 = cr
+ i1 = coeff i0 = y
- Where coeffs have the following layout in memory.
+Where coeffs have the following layout in memory.
- uint32_t oy,oc,zero,cy,crv,rmask,cbu,bmask,cgu,cgv;
+uint32_t oy,oc,zero,cy,crv,rmask,cbu,bmask,cgu,cgv;
- coeffs is a pointer to oy.
+coeffs is a pointer to oy.
- the {rgb} masks are only utilized by the 565 packing algorithm. Note the data
- replication is used to simplify the internal algorithms for the dual mac architecture
- of BlackFin.
+The {rgb} masks are only utilized by the 565 packing algorithm. Note the data
+replication is used to simplify the internal algorithms for the dual Mac
+architecture of BlackFin.
- All routines are exported with _ff_bfin_ as a symbol prefix
+All routines are exported with _ff_bfin_ as a symbol prefix.
- rough performance gain compared against -O3:
+Rough performance gain compared against -O3:
- 2779809/1484290 187.28%
-
- which translates to ~33c/pel to ~57c/pel for the reference vs 17.5
- c/pel for the optimized implementations. Not sure why there is such a
- huge variation on the reference codes on Blackfin I guess it must have
- to do with the memory system.
+2779809/1484290 187.28%
+which translates to ~33c/pel to ~57c/pel for the reference vs 17.5
+c/pel for the optimized implementations. Not sure why there is such a
+huge variation on the reference codes on Blackfin I guess it must have
+to do with the memory system.
*/
-#define mL1 .l1.text
#define mL3 .text
+#ifdef __FDPIC__
+#define mL1 .l1.text
+#else
+#define mL1 mL3
+#endif
#define MEM mL1
#define DEFUN(fname,where,interface) \
projects / ffmpeg / blobdiff