1 files changed, 91 insertions, 115 deletions

diff --git a/firmware/target/arm/ipod/video/lcd-video.c b/firmware/target/arm/ipod/video/lcd-video.c
index 237162b664..27f31c3511 100644
--- a/firmware/target/arm/ipod/video/lcd-video.c
+++ b/firmware/target/arm/ipod/video/lcd-video.c
@@ -104,7 +104,7 @@ static void lcd_bcm_setup_rect(unsigned cmd,
     lcd_bcm_write32(0xE001C, 0);
 }
 
-static unsigned lcd_bcm_read32(unsigned address) {
+static inline unsigned lcd_bcm_read32(unsigned address) {
     while ((inw(0x30020000) & 1) == 0);
 
     /* write out destination address as two 16bit values */
@@ -205,27 +205,39 @@ void lcd_update(void)
     lcd_update_rect(0, 0, LCD_WIDTH, LCD_HEIGHT);
 }
 
-#define CSUB_X 2
-#define CSUB_Y 2
-
-#define RYFAC (31*257)
-#define GYFAC (31*257)
-#define BYFAC (31*257)
-#define RVFAC 11170     /* 31 * 257 *  1.402    */
-#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)
+/*   YUV- > RGB565 conversion
+ *   |R|   |1.000000 -0.000001  1.402000| |Y'|
+ *   |G| = |1.000000 -0.334136 -0.714136| |Pb|
+ *   |B|   |1.000000  1.772000  0.000000| |Pr|
+ *   Scaled, normalized, rounded and tweaked to yield RGB 565:
+ *   |R|   |74   0 101| |Y' -  16| >> 9
+ *   |G| = |74 -24 -51| |Cb - 128| >> 8
+ *   |B|   |74 128   0| |Cr - 128| >> 9
+*/
+
+#define RGBYFAC   74   /*  1.0      */
+#define RVFAC    101   /*  1.402    */
+#define GVFAC   (-51)  /* -0.714136 */
+#define GUFAC   (-24)  /* -0.334136 */
+#define BUFAC    128   /*  1.772    */
+
+/* ROUNDOFFS contain constant for correct round-offs as well as
+   constant parts of the conversion matrix (e.g. (Y'-16)*RGBYFAC
+   -> constant part = -16*RGBYFAC). Through extraction of these
+   constant parts we save at leat 4 substractions in the conversion
+   loop */
+#define ROUNDOFFSR (256 - 16*RGBYFAC - 128*RVFAC)
+#define ROUNDOFFSG (128 - 16*RGBYFAC - 128*GVFAC - 128*GUFAC)
+#define ROUNDOFFSB (256 - 16*RGBYFAC             - 128*BUFAC)
+
+#define MAX_5BIT 0x1f
+#define MAX_6BIT 0x3f
 
 /* Performance function to blit a YUV bitmap directly to the LCD */
 void lcd_yuv_blit(unsigned char * const src[3],
                   int src_x, int src_y, int stride,
                   int x, int y, int width, int height)
 {
-    int ymax;
-
     width = (width + 1) & ~1;
 
     if (finishup_needed) {
@@ -261,119 +273,83 @@ void lcd_yuv_blit(unsigned char * const src[3],
     /* wait for it to be write ready */
     while ((inw(0x30030000) & 0x2) == 0);
 
-    ymax = y + height - 1 ;
-
-    const int stride_div_csub_x = stride/CSUB_X;
+    const int ymax = y + height - 1;
+    const int stride_div_sub_x = stride >> 1;
+    unsigned char *ysrc = 0;
+    unsigned char *usrc = 0;
+    unsigned char *vsrc = 0;
+    unsigned char *row_end = 0;
+    int uvoffset;
+    int yp, up, vp, rc, gc, bc; /* temporary variables */
+    int red1, green1, blue1;    /* contain RGB of 1st pixel */
+    int red2, green2, blue2;    /* contain RGB of 2nd pixel */
 
     for (; y <= ymax ; y++)
     {
         /* 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 red1, green1, blue1;
-        int red2, green2, blue2;
-        unsigned rbits, gbits, bbits;
-
-        int rc, gc, bc;
+        uvoffset = stride_div_sub_x*(src_y >> 1) + (src_x >> 1);
+        ysrc = src[0] + stride * src_y + src_x;
+        usrc = src[1] + uvoffset;
+        vsrc = src[2] + uvoffset;
+        
+        row_end = ysrc + width;
 
         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++;
-
-            red1   = RYFAC * y + rc;
-            green1 = GYFAC * y + gc;
-            blue1  = BYFAC * y + bc;
-
-            /* Pixel 2 */
-            y = *ysrc++;
-            red2   = RYFAC * y + rc;
-            green2 = GYFAC * y + gc;
-            blue2  = BYFAC * y + bc;
-
+            up = *usrc++;
+            vp = *vsrc++;
+            rc = RVFAC * vp              + ROUNDOFFSR;
+            gc = GVFAC * vp + GUFAC * up + ROUNDOFFSG;
+            bc =              BUFAC * up + ROUNDOFFSB;
+            
+            /* Pixel 1 -> RGB565 */
+            yp = *ysrc++ * RGBYFAC;
+            red1   = (yp + rc) >> 9;
+            green1 = (yp + gc) >> 8;
+            blue1  = (yp + bc) >> 9;
+
+            /* Pixel 2 -> RGB565 */
+            yp = *ysrc++ * RGBYFAC;
+            red2   = (yp + rc) >> 9;
+            green2 = (yp + gc) >> 8;
+            blue2  = (yp + bc) >> 9;
+            
             /* 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);
-                    }
+               negative values both being !=0 when bitmasking them.
+               We first check for red and blue components (5bit range). */
+            if ((red1 | blue1 | red2 | blue2) & ~MAX_5BIT)
+            {
+                if ((red1 | blue1) & ~MAX_5BIT)
+                {
+                    if (red1 & ~MAX_5BIT)
+                        red1  = (red1  >> 31) ? 0 : MAX_5BIT;
+                    if (blue1 & ~MAX_5BIT)
+                        blue1 = (blue1 >> 31) ? 0 : MAX_5BIT;
                 }
-
-                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);
-                    }
+                if ((red2 | blue2) & ~MAX_5BIT)
+                {
+                    if (red2 & ~MAX_5BIT)
+                        red2  = (red2 >> 31) ? 0 : MAX_5BIT;
+                    if (blue2 & ~MAX_5BIT)
+                        blue2 = (blue2 >> 31) ? 0 : MAX_5BIT;
                 }
             }
-                
-            rbits = red1 >> 16 ;
-            gbits = green1 >> 15 ;
-            bbits = blue1 >> 16 ;
-
-            outw((rbits << 11) | (gbits << 5) | bbits, 0x30000000);
+            /* We second check for green component (6bit range) */
+            if ((green1 | green2) & ~MAX_6BIT)
+            {
+                    if (green1 & ~MAX_6BIT)
+                        green1 = (green1 >> 31) ? 0 : MAX_6BIT;
+                    if (green2 & ~MAX_6BIT)
+                        green2 = (green2 >> 31) ? 0 : MAX_6BIT;
+            }
+            
+            /* pixel1 */
+            outw((red1 << 11) | (green1 << 5) | blue1, 0x30000000);
 
-            rbits = red2 >> 16 ;
-            gbits = green2 >> 15 ;
-            bbits = blue2 >> 16 ;
-            outw((rbits << 11) | (gbits << 5) | bbits, 0x30000000);
+            /* pixel2 */
+            outw((red2 << 11) | (green2 << 5) | blue2, 0x30000000);
         }
         while (ysrc < row_end);