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 23 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