Digital Photo Keychain User Manual

INSTRUCTION DESCRIPTIONS

A - 156 INSTRUCTION SET DETAILS MOTOROLA

Instruction Fields 1:

S1∗S2 Q Q Q Sign k D d

X0 X0 0 0 0 + 0 A 0

Y0 Y0 0 0 1 – 1 B 1

X1 X0 0 1 0

Y1 Y0 0 1 1

X0 Y1 1 0 0

Y0 X0 1 0 1

X1 Y0 1 1 0

Y1 X1 1 1 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:

MACR -Y0, #10, B ;

Explanation of Example 2

: The content of Y0 ($654321) is negated, multiplied by 2

-10

added to the content of the B accumulator ($00:100000:000000), placed in the B accu-

mulator and then rounded to a single precision number (24 bits in B1). The net effect of

this operation is to negate the content of Y0, divide the result by 2

and add the result

to the accumulator. An alternate interpretation is that Y0 is negated, right shifted 10

places, filled with the sign bit (0 for a positive number and 1 for a negative number), the

result is added to the accumulator and then rounded to a single precision number.

MACR Signed Multiply-Accumulate and Round MACR

Before Execution After Execution

$654321

B B

$00:100000:000000 $00:0FE6AF:000000

$654321