Digital Photo Keychain User Manual

INSTRUCTION DESCRIPTIONS
A - 152 INSTRUCTION SET DETAILS MOTOROLA
Timing: 2+mv oscillator clock cycles
Memory: 1+mv program words
Example 2:
:
MAC X0, #3, A ;
:
Explanation of Example 2: The content of X0 ($654321) is multiplied by 2
-3
and then
added to the content of the A accumulator ($00:100000:000000). The result is then
placed in the A accumulator. The net effect of this operation is to divide the content of
X0 by 2
3
and add the result to the accumulator. An alternate interpretation is that X0 is
right shifted 3 places and filled with the sign bit (0 for a positive number and 1 for a neg-
ative number) and then the result is added to the accumulator.
Instruction Format 2:
MAC (
±)S,#n,D
Opcode 2:
Instruction Fields:
S Q Q Sign k D d
Y1 0 0 + 0 A 0
X0 0 1 – 1 B 1
Y0 1 0
X1 1 1
MAC Signed Multiply-Accumulate MAC
Before Execution After Execution
X0
$654321
A A
$00:100000:000000 $00:1CA864:200000
$654321
X0
23 16 15 8 7 0
00000001000sssss11QQdk10