dsp56000 Freescale Semiconductor, Inc, dsp56000 Datasheet - Page 500

• Manufacturer Part Number: dsp56000
• Description: 24-bit Digital Signal Processor Family Manual
• Manufacturer: Freescale Semiconductor, Inc

Instruction Fields 1:
Note: Only the indicated S1 S2 combinations are valid. X1 X1 and Y1 Y1 are not valid.
Timing: 2+mv oscillator clock cycles
Memory: 1+mv program words
Example 2:
Explanation of Example 2: The content of Y1 is negated, multiplied by 2
a single precision number (24 bits in B1) and placed in the B accumulator. The net effect
of this operation is negate the content of Y1 and divide the result by 2
in the accumulator and then round to a single precision number. An alternate interpreta-
tion is that X1 is negated and placed in the accumulator, right shift ed 14 places, filled
with the sign bit (0 for a positive number and 1 for a negative number) and then rounded
to a single precision number.
A - 234
MPYR
MPYR -Y1,
S1 S2
X0 X0
Y0 Y0
X1 X0
Y1 Y0
X0 Y1
Y0 X0
X1 Y0
Y1 X1
Y1
B
:
:
Q Q Q
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
#14, B
$00:000000:000000
Before Execution
Freescale Semiconductor, Inc.
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INSTRUCTION DESCRIPTIONS
INSTRUCTION SET DETAILS
Signed Multiply and Round
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Sign k
+
–
;
1
0
Y1
B
D d
A 0
B 1
$FF:FFFE6B:000000
After Execution
$654321
14
, place the result
-14
MPYR
MOTOROLA
, rounded to