Typo in a comment: s/two avoid/to avoid/

[ffmpeg.git] / libswscale / internal_bfin.S

diff --git a/libswscale/internal_bfin.S b/libswscale/internal_bfin.S
index 91325af..fb7bda7 100644 (file)
--- a/libswscale/internal_bfin.S
+++ b/libswscale/internal_bfin.S
@@ -2,8 +2,8 @@
  * Copyright (C) 2007 Marc Hoffman <marc.hoffman@analog.com>
  *                    April 20, 2007
  *
  * 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.
  *
  *
  * This file is part of FFmpeg.
  *


@@ -24,78 +24,81 @@
 
 
 /*
 
 
 /*

-    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
 #define mL3 .text

+#ifdef __FDPIC__
+#define mL1 .l1.text
+#else
+#define mL1 mL3
+#endif

 #define MEM mL1
 
 #define DEFUN(fname,where,interface) \
 #define MEM mL1
 
 #define DEFUN(fname,where,interface) \