Fake truecolor support using a RGB:332 palette.

function                                             old     new   delta
fb_setpal                                              -     212    +212
fbsplash_main                                       1136    1184     +48
fb_pixel_value                                        52      84     +32
fb_write_pixel                                        60      68      +8
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 3/0 up/down: 300/0)             Total: 300 bytes

Signed-off-by: Peter Korsgaard <[email protected]>
---
 miscutils/fbsplash.c |   52 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 51 insertions(+), 1 deletions(-)

diff --git a/miscutils/fbsplash.c b/miscutils/fbsplash.c
index 937c6a4..d9077c5 100644
--- a/miscutils/fbsplash.c
+++ b/miscutils/fbsplash.c
@@ -74,6 +74,33 @@ struct globals {
 #define DEBUG_MESSAGE(...) ((void)0)
 #endif
 
+/**
+ * Configure palette for RGB:332
+ */
+static void fb_setpal(int fd)
+{
+       struct fb_cmap cmap;
+       /* fb colors are 16 bit */
+       unsigned short red[256], green[256], blue[256];
+       int i;
+
+       /* RGB:332 */
+       for (i = 0; i < 256; i++)
+       {
+               red[i]   = ((i & 0xe0) << 8)  + ((i & 0x20) ? 0x1fff : 0);
+               green[i] = ((i & 0x1c) << 11) + ((i & 0x04) ? 0x1fff : 0);
+               blue[i]  = ((i & 0x03) << 14) + ((i & 0x01) ? 0x3fff : 0);
+       }
+
+       cmap.start = 0;
+       cmap.len   = 256;
+       cmap.red   = red;
+       cmap.green = green;
+       cmap.blue  = blue;
+       cmap.transp = 0;
+
+       xioctl(fd, FBIOPUTCMAP, &cmap);
+}
 
 /**
  * Open and initialize the framebuffer device
@@ -87,8 +114,21 @@ static void fb_open(const char *strfb_device)
        xioctl(fbfd, FBIOGET_VSCREENINFO, &G.scr_var);
        xioctl(fbfd, FBIOGET_FSCREENINFO, &G.scr_fix);
 
-       if (G.scr_var.bits_per_pixel < 16 || G.scr_var.bits_per_pixel > 32)
+       switch (G.scr_var.bits_per_pixel) {
+       case 8:
+               fb_setpal(fbfd);
+               break;
+
+       case 16:
+       case 24:
+       case 32:
+               break;
+
+       default:
                bb_error_msg_and_die("unsupported %u bpp", 
(int)G.scr_var.bits_per_pixel);
+               break;
+       }
+
        G.bytes_per_pixel = (G.scr_var.bits_per_pixel + 7) >> 3;
 
        // map the device in memory
@@ -109,6 +149,13 @@ static void fb_open(const char *strfb_device)
  */
 static unsigned fb_pixel_value(unsigned r, unsigned g, unsigned b)
 {
+       if (G.bytes_per_pixel == 1) {
+               r >>= 5;  // 3-bit red
+               g >>= 5;  // 3-bit green
+               b >>= 6;  // 2-bit blue
+               return b + (g << 2) + (r << (2+3));
+       }
+
        if (G.bytes_per_pixel == 2) {
                r >>= 3;  // 5-bit red
                g >>= 2;  // 6-bit green
@@ -125,6 +172,9 @@ static unsigned fb_pixel_value(unsigned r, unsigned g, 
unsigned b)
 static void fb_write_pixel(unsigned char *addr, unsigned pixel)
 {
        switch (G.bytes_per_pixel) {
+       case 1:
+               *addr = pixel;
+               break;
        case 2:
                *(uint16_t *)addr = pixel;
                break;
-- 
1.7.6.3

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