/*
 * Compute size of DRAM based on contents of the Madam System Control Register.
 *
 *             |  x8 == 0   |  x8 == 0  |  x8 == 1
 *  MSYS       | MSYS DRAM  | MSYS DRAM | MSYS
 *  2:0  VRAM  | 6:5  SET0  | 4:3 SET1  | 6:3  DRAM
 *  ---  ----  | ---- ----  | ---- ---- | ---- ----
 *             |  00  0 MB  |  00 0 MB  |
 *  001  1 MB  |  01  1 MB  |  01 1 MB  | 0101 2 MB
 *  010  2 MB  |  10  4 MB  |  10 4 MB  | 1010 8 MB
 *
 * Combinations not shown in the above tables are not supported and
 * this routine is not guaranteed to return anything sensible (even
 * though it usually will do something vaguely rational).
 */
void
FindMemSize(uint32 *pDramSize, uint32 *pVramSize)
{
    uint32 bits = *MSYSBits;
    uint32 dram_size;
    uint32 vram_size;

    /*
     * This may look complex, but it only takes about eight ARM
     * instructions to evaluate. Basicly, take each DRAM set size
     * field, and double it to get the left-shift count. Then
     * shift "a quarter megabyte" left by the count, casting off
     * anything less than a megabyte; this is easiest to do if you
     * shift "1" left by the count, then right by two. We turn it
     * into megabytes later.
     */
    dram_size =
        (((1<<((bits>> (DRAMSIZE_SET0SHIFT-1))&(DRAMSIZE_SETMASK<<1)))>>2) +
         ((1<<((bits>> (DRAMSIZE_SET1SHIFT-1))&(DRAMSIZE_SETMASK<<1)))>>2));

    vram_size = ((bits & VRAMSIZE_MASK)>> VRAMSIZE_SHIFT);

    /* Convert to megabytes */
    *pDramSize = dram_size * 1024*1024;
    *pVramSize = vram_size * 1024*1024;
}