swscale: remove unused U/V arguments from yuv2rgb_write().

Also document the function somewhat.

libswscale/swscale.c

@@ -884,9 +884,17 @@ YUV2PACKED16WRAPPER(yuv2, rgb48, rgb48le, PIX_FMT_RGB48LE)
 YUV2PACKED16WRAPPER(yuv2, rgb48, bgr48be, PIX_FMT_BGR48BE)
 YUV2PACKED16WRAPPER(yuv2, rgb48, bgr48le, PIX_FMT_BGR48LE)
 
+/*
+ * Write out 2 RGB pixels in the target pixel format. This function takes a
+ * R/G/B LUT as generated by ff_yuv2rgb_c_init_tables(), which takes care of
+ * things like endianness conversion and shifting. The caller takes care of
+ * setting the correct offset in these tables from the chroma (U/V) values.
+ * This function then uses the luminance (Y1/Y2) values to write out the
+ * correct RGB values into the destination buffer.
+ */
 static av_always_inline void
 yuv2rgb_write(uint8_t *_dest, int i, unsigned Y1, unsigned Y2,
-              unsigned U, unsigned V, unsigned A1, unsigned A2,
+              unsigned A1, unsigned A2,
               const void *_r, const void *_g, const void *_b, int y,
               enum PixelFormat target, int hasAlpha)
 {
@@ -1053,7 +1061,7 @@ yuv2rgb_X_c_template(SwsContext *c, const int16_t *lumFilter,
         g = (c->table_gU[U] + c->table_gV[V]);
         b =  c->table_bU[U];
 
-        yuv2rgb_write(dest, i, Y1, Y2, U, V, hasAlpha ? A1 : 0, hasAlpha ? A2 : 0,
+        yuv2rgb_write(dest, i, Y1, Y2, hasAlpha ? A1 : 0, hasAlpha ? A2 : 0,
                       r, g, b, y, target, hasAlpha);
     }
 }
@@ -1089,7 +1097,7 @@ yuv2rgb_2_c_template(SwsContext *c, const int16_t *buf[2],
             A2 = (abuf0[i * 2 + 1] * yalpha1 + abuf1[i * 2 + 1] * yalpha) >> 19;
         }
 
-        yuv2rgb_write(dest, i, Y1, Y2, U, V, hasAlpha ? A1 : 0, hasAlpha ? A2 : 0,
+        yuv2rgb_write(dest, i, Y1, Y2, hasAlpha ? A1 : 0, hasAlpha ? A2 : 0,
                       r, g, b, y, target, hasAlpha);
     }
 }
@@ -1121,7 +1129,7 @@ yuv2rgb_1_c_template(SwsContext *c, const int16_t *buf0,
                 A2 = abuf0[i * 2 + 1] >> 7;
             }
 
-            yuv2rgb_write(dest, i, Y1, Y2, U, V, hasAlpha ? A1 : 0, hasAlpha ? A2 : 0,
+            yuv2rgb_write(dest, i, Y1, Y2, hasAlpha ? A1 : 0, hasAlpha ? A2 : 0,
                           r, g, b, y, target, hasAlpha);
         }
     } else {
@@ -1140,7 +1148,7 @@ yuv2rgb_1_c_template(SwsContext *c, const int16_t *buf0,
                 A2 = abuf0[i * 2 + 1] >> 7;
             }
 
-            yuv2rgb_write(dest, i, Y1, Y2, U, V, hasAlpha ? A1 : 0, hasAlpha ? A2 : 0,
+            yuv2rgb_write(dest, i, Y1, Y2, hasAlpha ? A1 : 0, hasAlpha ? A2 : 0,
                           r, g, b, y, target, hasAlpha);
         }
     }