Configure address translation for XIP virtual addresses 0x800000 through 0xbfffff (a 4 MiB window starting at +8 MiB).
Address translation allows a program image to be executed in place at multiple physical flash addresses (for example, a double-buffered flash image for over-the-air updates), without the overhead of position-independent code.
At reset, the address translation registers are initialised to an identity mapping, so that they can be ignored if address translation is not required.
Note that the XIP cache is fully virtually addressed, so a cache flush is required after changing the address translation.
| BASE | Physical address base for this virtual address range, in units of 4 kiB (one flash sector). Taking a 24-bit virtual address, firstly bits 23:22 (the two MSBs) are masked to zero, and then BASE is added to bits 23:12 (the upper 12 bits) to form the physical address. Translation wraps on a 16 MiB boundary. |
| SIZE | Translation aperture size for this virtual address range, in units of 4 kiB (one flash sector). Bits 21:12 of the virtual address are compared to SIZE. Offsets greater than SIZE return a bus error, and do not cause a QSPI access. |