Jun Sun (email@example.com) writes:
> The USB sub-system uses "unaligned.h" file to access unaligned data.
> All the unaligned data access functions depend on "uld" and "usw"
> instructions, which are not available on many CPUs.
You won't find the instruction 'uld' in *any* MIPS CPU.
uld is an assembler macro-instruction translating into a
pair (the instructions are called load-double-left and
load-double-right). The exact translation depends on whether you're
running big-endian or little-endian... but the 32-bit version on a
big-endian CPU is that
ulw $1, <address>
is assembled as
lwl $1, <address>
lwr $1, <address+3>
The way that the load-left and load-right work together is kind of
tricky to get your head round.
So far as I know, all 64-bit MIPS CPUs implement ldl/ldr and the store
equivalents. MIPS patented these instructions, so clones like Lexra's
don't implement the 32-bit versions (lwl, lwr etc).
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