Port Tom Meyer's lcd_yuv_blit() optimisations for the ipod 5g to the ipod Photo/Color and Nano - gives a similar 10-15% speedup in mpegplayer.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@10629 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 100 insertions, 80 deletions

diff --git a/firmware/drivers/lcd-ipod.c b/firmware/drivers/lcd-ipod.c
index d39aad163f..ed2847d665 100644
--- a/firmware/drivers/lcd-ipod.c
+++ b/firmware/drivers/lcd-ipod.c
@@ -404,14 +404,15 @@ void lcd_blit(const fb_data* data, int x, int by, int width,
 #define CSUB_Y 2
 
 #define RYFAC (31*257)
-#define GYFAC (63*257)
+#define GYFAC (31*257)
 #define BYFAC (31*257)
 #define RVFAC 11170     /* 31 * 257 *  1.402    */
-#define GVFAC (-11563)  /* 63 * 257 * -0.714136 */
-#define GUFAC (-5572)   /* 63 * 257 * -0.344136 */
+#define GVFAC (-5690)  /* 31 * 257 * -0.714136 */
+#define GUFAC (-2742)   /* 31 * 257 * -0.344136 */
 #define BUFAC 14118     /* 31 * 257 *  1.772    */
 
 #define ROUNDOFFS (127*257)
+#define ROUNDOFFSG (63*257)
 
 /* Performance function to blit a YUV bitmap directly to the LCD */
 void lcd_yuv_blit(unsigned char * const src[3],
@@ -478,14 +479,27 @@ void lcd_yuv_blit(unsigned char * const src[3],
         lcd_send_lo(LCD_CNTL_WRITE_TO_GRAM);
     }
 
+    const int stride_div_csub_x = stride/CSUB_X;
+
     h=0;
     while (1) {
-        int pixels_to_write;
+        /* upsampling, YUV->RGB conversion and reduction to RGB565 in one go */
         const unsigned char *ysrc = src[0] + stride * src_y + src_x;
+
+        const int uvoffset = stride_div_csub_x * (src_y/CSUB_Y) +
+                             (src_x/CSUB_X);
+
+        const unsigned char *usrc = src[1] + uvoffset;
+        const unsigned char *vsrc = src[2] + uvoffset;
         const unsigned char *row_end = ysrc + width;
+
         int y, u, v;
-        int red, green, blue;
+        int red1, green1, blue1;
+        int red2, green2, blue2;
         unsigned rbits, gbits, bbits;
+
+        int rc, gc, bc;
+        int pixels_to_write;
         fb_data pixel1,pixel2;
 
         if (h==0) {
@@ -509,90 +523,96 @@ void lcd_yuv_blit(unsigned char * const src[3],
             outl(0x34000000, 0x70008a20);
         }
 
-        /* upsampling, YUV->RGB conversion and reduction to RGB565 in one go */
-        const unsigned char *usrc = src[1] + (stride/CSUB_X) * (src_y/CSUB_Y)
-                                           + (src_x/CSUB_X);
-        const unsigned char *vsrc = src[2] + (stride/CSUB_X) * (src_y/CSUB_Y)
-                                           + (src_x/CSUB_X);
-        int rc, gc, bc;
-
-        u = *usrc++ - 128;
-        v = *vsrc++ - 128;
-        rc = RVFAC * v + ROUNDOFFS;
-        gc = GVFAC * v + GUFAC * u + ROUNDOFFS;
-        bc = BUFAC * u + ROUNDOFFS;
-
         do
         {
+            u = *usrc++ - 128;
+            v = *vsrc++ - 128;
+            rc = RVFAC * v + ROUNDOFFS;
+            gc = GVFAC * v + GUFAC * u + ROUNDOFFSG;
+            bc = BUFAC * u + ROUNDOFFS;
+
+            /* Pixel 1 */
             y = *ysrc++;
-            red   = RYFAC * y + rc;
-            green = GYFAC * y + gc;
-            blue  = BYFAC * y + bc;
-
-            if ((unsigned)red > (RYFAC*255+ROUNDOFFS))
-            {
-                if (red < 0)
-                    red = 0;
-                else
-                    red = (RYFAC*255+ROUNDOFFS);
-            }
-            if ((unsigned)green > (GYFAC*255+ROUNDOFFS))
-            {
-                if (green < 0)
-                    green = 0;
-                else
-                    green = (GYFAC*255+ROUNDOFFS);
-            }
-            if ((unsigned)blue > (BYFAC*255+ROUNDOFFS))
-            {
-                if (blue < 0)
-                    blue = 0;
-                else
-                    blue = (BYFAC*255+ROUNDOFFS);
-            }
-            rbits = ((unsigned)red) >> 16 ;
-            gbits = ((unsigned)green) >> 16 ;
-            bbits = ((unsigned)blue) >> 16 ;
 
-            pixel1 = swap16((rbits << 11) | (gbits << 5) | bbits);
+            red1   = RYFAC * y + rc;
+            green1 = GYFAC * y + gc;
+            blue1  = BYFAC * y + bc;
 
+            /* Pixel 2 */
             y = *ysrc++;
-            red   = RYFAC * y + rc;
-            green = GYFAC * y + gc;
-            blue  = BYFAC * y + bc;
-
-            if ((unsigned)red > (RYFAC*255+ROUNDOFFS))
-            {
-                if (red < 0)
-                    red = 0;
-                else
-                    red = (RYFAC*255+ROUNDOFFS);
-            }
-            if ((unsigned)green > (GYFAC*255+ROUNDOFFS))
-            {
-                if (green < 0)
-                    green = 0;
-                else
-                    green = (GYFAC*255+ROUNDOFFS);
-            }
-            if ((unsigned)blue > (BYFAC*255+ROUNDOFFS))
-            {
-                if (blue < 0)
-                    blue = 0;
-                else
-                    blue = (BYFAC*255+ROUNDOFFS);
+            red2   = RYFAC * y + rc;
+            green2 = GYFAC * y + gc;
+            blue2  = BYFAC * y + bc;
+
+            /* Since out of bounds errors are relatively rare, we check two
+               pixels at once to see if any components are out of bounds, and
+               then fix whichever is broken. This works due to high values and
+               negative values both becoming larger than the cutoff when
+               casted to unsigned.  And ORing them together checks all of them
+               simultaneously.  */
+            if (((unsigned)(red1 | green1 | blue1 |
+                     red2 | green2 | blue2)) > (RYFAC*255+ROUNDOFFS)) {
+                if (((unsigned)(red1 | green1 | blue1)) > 
+                    (RYFAC*255+ROUNDOFFS)) {
+                    if ((unsigned)red1 > (RYFAC*255+ROUNDOFFS))
+                    {
+                        if (red1 < 0)
+                            red1 = 0;
+                        else
+                            red1 = (RYFAC*255+ROUNDOFFS);
+                    }
+                    if ((unsigned)green1 > (GYFAC*255+ROUNDOFFSG))
+                    {
+                        if (green1 < 0)
+                            green1 = 0;
+                        else
+                            green1 = (GYFAC*255+ROUNDOFFSG);
+                    }
+                    if ((unsigned)blue1 > (BYFAC*255+ROUNDOFFS))
+                    {
+                        if (blue1 < 0)
+                            blue1 = 0;
+                        else
+                            blue1 = (BYFAC*255+ROUNDOFFS);
+                    }
+                }
+
+                if (((unsigned)(red2 | green2 | blue2)) > 
+                    (RYFAC*255+ROUNDOFFS)) {
+                    if ((unsigned)red2 > (RYFAC*255+ROUNDOFFS))
+                    {
+                        if (red2 < 0)
+                            red2 = 0;
+                        else
+                            red2 = (RYFAC*255+ROUNDOFFS);
+                    }
+                    if ((unsigned)green2 > (GYFAC*255+ROUNDOFFSG))
+                    {
+                        if (green2 < 0)
+                            green2 = 0;
+                        else
+                            green2 = (GYFAC*255+ROUNDOFFSG);
+                    }
+                    if ((unsigned)blue2 > (BYFAC*255+ROUNDOFFS))
+                    {
+                        if (blue2 < 0)
+                            blue2 = 0;
+                        else
+                            blue2 = (BYFAC*255+ROUNDOFFS);
+                    }
+                }
             }
-            rbits = ((unsigned)red) >> 16 ;
-            gbits = ((unsigned)green) >> 16 ;
-            bbits = ((unsigned)blue) >> 16 ;
+                
+            rbits = red1 >> 16 ;
+            gbits = green1 >> 15 ;
+            bbits = blue1 >> 16 ;
 
-            pixel2 = swap16((rbits << 11) | (gbits << 5) | bbits);
+            pixel1 = swap16((rbits << 11) | (gbits << 5) | bbits);
 
-            u = *usrc++ - 128;
-            v = *vsrc++ - 128;
-            rc = RVFAC * v + ROUNDOFFS;
-            gc = GVFAC * v + GUFAC * u + ROUNDOFFS;
-            bc = BUFAC * u + ROUNDOFFS;
+            rbits = red2 >> 16 ;
+            gbits = green2 >> 15 ;
+            bbits = blue2 >> 16 ;
+            pixel2 = swap16((rbits << 11) | (gbits << 5) | bbits);
 
             while ((inl(0x70008a20) & 0x1000000) == 0);