Analog Devices ADSP-BF53x Blackfin, Reference

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ADSP-BF53x/BF56x Blackfin Processor Programming Reference 5-9
Address Arithmetic Unit
For example:
R0 = [ I2 ]
;
loads a 32-bit value from an address pointed to by
I2
and stores it in the
destination register
R0
.
R0.H = W [ I2 ]
;
loads a 16-bit value from an address pointed to by
I2
and stores it in the
16-bit destination register
R0.H.
[ P1 ] = R0
;
is an example of a 32-bit store operation.
Pointer registers can be used for 8-bit loads and stores.
For example:
B [ P1++ ] = R0
;
stores the 8-bit value from the
R0
register in the address pointed to by the
P1
register, then increments the
P1
register.
Loads With Zero or Sign Extension
When a 32-bit register is loaded by an 8-bit or 16-bit memory read, the
value can be extended to the full register width. A trailing Z character in
parenthesis is used to zero-extend the loaded value. An X character forces
sign extension. The following examples assume that
P1
points to a mem-
ory location that contains a value of 0x8080.
R0 = W[P1] (Z) ; /* R0 = 0x0000 8080 */
R1 = W[P1] (X) ; /* R1 = 0xFFFF 8080 */
R2 = B[P1] (Z) ; /* R2 = 0x0000 0080 */
R3 = B[P1] (X) ; /* R3 = 0xFFFF FF80 */