高深的问题

caobinec

高深的问题 [复制链接]

如下这个函数是在WINCE的BSP里面的,pTOC是ROMHDR结构,/* Routine to copy the flashed NK image to RAM */
int EverythingRelocate(void)
{
    LONG len;
    ROMHDR *ptoc;
    ULONG pc, *toc, offset, dest;

    /*
     * First make sure we're running in flash, in
     * which case we want to copy everything into
     * RAM.
     */
    pc = GetPC();
    if ((pc <= PHYS_FLASH_BASE) || (pc >= ARMVPB_FLASH_END))
        return -1;

    /*
     * The image has been built to run in RAM
     * but is currently stored in flash,
     * so we have to calculate the pTOC's address
     * relative to the flash address.
     */
    offset = NK_FLASH_BASE - ((ULONG)(&pTOC) & 0xffff0000);

        //LJP ADD
          RETAILMSG(1, (TEXT("-ROM OFFSET  0X%X\r\n"), offset));
    toc = (ULONG *)((LONG)(&pTOC) + offset);
    ptoc = (ROMHDR *)((LONG)(*toc) + offset);

    if( ptoc == (ROMHDR *)-1 )
    {
        lpWriteDebugStringFunc(TEXT("No TOC found!\r\n"));
        while( 1 )
        {
            /* Spin Forever */ ;
        }
    }

    len = (ptoc->physlast - ptoc->physfirst);
    /*
     * Convert the start address from a Virtual to a Physical
     * address as the MMU is not on yet.
     */
    dest = ptoc->physfirst - VA_RAM_BASE + PHYS_RAM_BASE;
    memcpy((void *)dest, (void *)NK_FLASH_BASE, len);
    /*
     * Return new memory location, but skip image header
     */
    return (dest + IMAGE_HEADER_SIZE);
}请问    offset = NK_FLASH_BASE - ((ULONG)(&pTOC) & 0xffff0000);
    toc = (ULONG *)((LONG)(&pTOC) + offset);
    ptoc = (ROMHDR *)((LONG)(*toc) + offset);这几句计算的意思是什么呀?谢谢,不胜感谢!

305932515

好高深，没看懂。

kvin

故弄玄虚

ysbqw

wince没去弄过,不过,肯定不是什么高深的问题.多看看帮助说明就知道的.

evilsop

等待牛人来答.