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RL78/G1A CHAPTER 14 MULTIPLIER AND DIVIDER/MULTIPLY-ACCUMULATOR
14.4.2 Multiplication (signed) operation
• Initial setting
<1> Set the multiplication/division control register (MDUC) to 08H.
<2> Set the multiplicand to multiplication/division data register A (L) (MDAL).
<3> Set the multiplier to multiplication/division data register A (H) (MDAH).
(There is no preference in the order of executing steps <2> and <3>. Multiplication operation is automatically
started when the multiplier and multiplicand are set to the MDAH and MDAL registers, respectively.)
• During operation processing
<4> Wait for at least one clock. The operation will end when one clock has been issued.
• Operation end
<5> Read the product (lower 16 bits) from multiplication/division data register B (L) (MDBL).
<6> Read the product (higher 16 bits) from multiplication/division data register B (H) (MDBH).
(There is no preference in the order of executing steps <5> and <6>.)
• Next operation
<7> Start with the initial settings of each step to change the operation mode. When the same operation mode is
used sequentially, settings <1> and <2> can be omitted.
Caution The data is in the two's complement format in multiplication mode (signed).
Remark Steps <1> to <7> correspond to <1> to <7> in Figure 14-7.
Figure 14-7. Timing Diagram of Multiplication (Signed) Operation (−2 × 32767 = −65534)
MDAL FFFFH
FFFFH
0000H
0001H
FFFEH
7FFFH
FFFFH
0002H
00H 08H
MDAH
MDBH
MDBL
MDUC
MDSM
8001H
FFFFH
<2>
<1>
<3> <5>, <6>
<4>
<7>
0000H
0000H
0000H
0000H
Operation clock
R01UH0305EJ0200 Rev.2.00 661
Jul 04, 2013