4.2. Bit-banding

The processor memory map includes two bit-band regions. These occupy the lowest 1MB of the SRAM and Peripheral memory regions respectively. These bit-band regions map each word in an alias region of memory to a bit in a bit-band region of memory.

The memory map has two 32-MB alias regions that map to two 1-MB bit-band regions:

A mapping formula shows how to reference each word in the alias region to a corresponding bit, or target bit, in the bit-band region. The mapping formula is:

bit_word_offset = (byte_offset x 32) + (bit_number × 4)
bit_word_addr = bit_band_base + bit_word_offset


Figure 4.2 shows examples of bit-band mapping between the SRAM bit-band alias region and the SRAM bit-band region:

Figure 4.2. Bit-band mapping

Copyright © 2005, 2006 ARM Limited. All rights reserved.ARM DDI 0337E