Syntax: SWP {<cond>}{B} <destination>, <operand1>, [<address>]
Operation: destination = value from memory at 'address'
value in memory at 'address' = operand1
Flags: Unaffected
This instruction swaps a word (or byte) in memory for a word (or byte) in a register,if <destination> and <operand1> are the same register they truly are swapped which is considerably less effort than a sequence of LDRs and STRs with the added advantage that the operation is atomic.
When a word fetch is made from a non-word aligned address, the data will be rotated right by 8 times the value in lower two bits of address. For byte fetches the alignment is unimportant and the upper 24 bits of <destination> are zeroed.
This instruction was introduced in ARM architecture 2A and later.
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