Posted on 2010-06-14 07:56
王小明 阅读(1520)
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先看手册怎么说：
will normally use a word aligned address. However, an
address offset from a word boundary will cause the data to be
rotated into the register so that the addressed byte occupies
bits 0 to 7. This means that half-words accessed at offsets 0
and 2 from the word boundary will be correctly loaded into
bits 0 through 15 of the register. Two shift operations are then
required to clear or to sign extend the upper 16 bits. This is
illustrated in Figure 5-15: Little Endian offset addressing on
page 5-21.
A word store (STR) should generate a word aligned address.
The word presented to the data bus is not affected if the
address is not word aligned. That is, bit 31 of the register
being stored always appears on data bus output 31.
就是说会rotate移位，一个0x12345678的值，在地址0x2，读取出来，会变成0x56781234
如果在地址0x1，读取出来，会变成0x34567812或者类似的效果，呵呵，本来以为会crash，然后说data misalignment，唉，没os就是麻烦。。。。。。