diff options
Diffstat (limited to 'miscutils')
| -rw-r--r-- | miscutils/fbsplash.c | 27 |
1 files changed, 22 insertions, 5 deletions
diff --git a/miscutils/fbsplash.c b/miscutils/fbsplash.c index 988439b..37ca665 100644 --- a/miscutils/fbsplash.c +++ b/miscutils/fbsplash.c @@ -50,6 +50,10 @@ struct globals { struct fb_var_screeninfo scr_var; struct fb_fix_screeninfo scr_fix; unsigned bytes_per_pixel; + // cached (8 - scr_var.COLOR.length): + unsigned red_shift; + unsigned green_shift; + unsigned blue_shift; }; #define G (*ptr_to_globals) #define INIT_G() do { \ @@ -139,6 +143,9 @@ static void fb_open(const char *strfb_device) break; } + G.red_shift = 8 - G.scr_var.red.length; + G.green_shift = 8 - G.scr_var.green.length; + G.blue_shift = 8 - G.scr_var.blue.length; G.bytes_per_pixel = (G.scr_var.bits_per_pixel + 7) >> 3; // map the device in memory @@ -155,10 +162,13 @@ static void fb_open(const char *strfb_device) /** - * Return pixel value of the passed RGB color + * Return pixel value of the passed RGB color. + * This is performance critical fn. */ static unsigned fb_pixel_value(unsigned r, unsigned g, unsigned b) { + /* We assume that the r,g,b values are <= 255 */ + if (G.bytes_per_pixel == 1) { r = r & 0xe0; // 3-bit red g = (g >> 3) & 0x1c; // 3-bit green @@ -166,10 +176,17 @@ static unsigned fb_pixel_value(unsigned r, unsigned g, unsigned b) return r + g + b; } if (G.bytes_per_pixel == 2) { - r = (r & 0xf8) << 8; // 5-bit red - g = (g & 0xfc) << 3; // 6-bit green - b = b >> 3; // 5-bit blue - return r + g + b; + // ARM PL110 on Integrator/CP has RGBA5551 bit arrangement. + // We want to support bit locations like that. + // + // First shift out unused bits + r = r >> G.red_shift; + g = g >> G.green_shift; + b = b >> G.blue_shift; + // Then shift the remaining bits to their offset + return (r << G.scr_var.red.offset) + + (g << G.scr_var.green.offset) + + (b << G.scr_var.blue.offset); } // RGB 888 return b + (g << 8) + (r << 16); |