Motorola MCF5282 ユーザーズマニュアル
3-4
MCF5282 User’s Manual
MOTOROLA
General Operation
For all operations, the resulting 40-bit product is extended to a 48-bit value (using
sign-extension for signed integer and fractional operands, zero-fill for unsigned integer
operands) before being combined with the 48-bit destination accumulator.
sign-extension for signed integer and fractional operands, zero-fill for unsigned integer
operands) before being combined with the 48-bit destination accumulator.
Figure 3-4 and Figure 3-5 show relative alignment of input operands, the full 64-bit
product, the resulting 40-bit product used for accumulation, and 48-bit accumulator
formats.
product, the resulting 40-bit product used for accumulation, and 48-bit accumulator
formats.
Figure 3-4. Fractional Alignment
Figure 3-5. Signed and Unsigned Integer Alignment
X
OperandY
OperandX
Product
Extended Product
Accumulator
32
8
Extension Byte Upper [7:0]
+
“0”
32
40
23
40
8
40
8
Accumulator [31:0]
Extension Byte Lower [7:0]
X
OperandY
OperandX
Product
Extended Product
Accumulator
32
32
32
32
32
8
8
8
24
8
8
+
Extension Byte Upper [7:0]
Extension Byte Lower [7:0]
Accumulator [31:0]