Motorola 24-Bit Digital Signal Processor manual Register and Y Memory Data Move Class II Example

INSTRUCTION DESCRIPTIONS

	R:Y	Register and Y Memory Data Move		R:Y
Class II Example:
:
	MAC X0,Y0,A	Y0,B B,Y:(R1)+	;multiply X0 and Y0 and accumulate in A
:			;move B to Y memory location pointed to
			;by R1 and postincrement R1
			;move Y0 to B

X0

Before Execution

$400000

X0

After Execution

$400000

Y0

$600000

Y0

$600000

A

$00:000000:000000

A

$00:300000:000000

B

$00:800000:000000

B

$00:600000:000000

Y:$1234

$000000

Y:$1234

$7FFFFF

R1

$1234

R1

$1235

Explanation of the Class II Example: Prior to execution, the 24-bit registers, X0 and Y0, contain $400000 and $600000, respectively. The 56-bit accumulators A and B con- tain the values $00:000000:000000 and $00:800000:000000 (+1.0000), respectively. The 24-bit Y memory location Y:$1234 contains the value $000000, and the 16-bit R1 register contains the value $1234. Execution of the parallel move portion of the instruc- tion (Y0,B B,Y:(R1)+) moves the Y0 register ($600000) into accumulator B1 ($600000), sign extends B1 into B2 ($00), and zero fills B0 ($000000). It also moves the 24-bit lim- ited value of B ($7FFFFF) into the Y:$1234 memory location and increments R1 to $1235.

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