Re: [U-Boot] [PATCH V2] lcd: align bmp header when uncopmressing image

Dear Piotr Wilczek,

In message 1370267979-17800-1-git-send-email-p.wilczek@samsung.com you wrote:

When compressed image is loaded, it must be decompressed to an aligned address + 2 to avoid unaligned access exception on some ARM platforms.

...

• dst = malloc(CONFIG_SYS_VIDEO_LOGO_MAX_SIZE);

• dst = malloc(CONFIG_SYS_VIDEO_LOGO_MAX_SIZE + 0x04);

Why + 4? This needs a comment. And please write 4 as 4, and not as 0x4 when there is no good reason for it.

• /* align to 32-bit-aligned-address + 2 */
• if ((unsigned int)bmp % 0x04 != 0x02)

• bmp = (bmp_image_t *)((((unsigned int)dst + 0x2) & ~0x1) | 0x2);
  

This is difficult to read and inefficient.

If you want to do it manually, just write it as

bmp = (bmp_image_t *)((((unsigned int)dst + 1) & ~3) + 2);

[Actually adding 3 to the "malloc()" size above would be sufficient with this].

A more readable way but slightly less efficient way might be:

u32_t n = (u32_t)dst;

bmp = (bmp_image_t *)(ALIGN(n, 4) + 2);

Best regards,

Wolfgang Denk