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RL78/G1A CHAPTER 14 MULTIPLIER AND DIVIDER/MULTIPLY-ACCUMULATOR
14.3 Register Controlling Multiplier and Divider/Multiply-Accumulator
The multiplier and divider/multiply-accumulator is controlled by using the multiplication/division control register (MDUC).
14.3.1 Multiplication/division control register (MDUC)
The MDUC register is an 8-bit register that controls the operation of the multiplier and divider/multiply-accumulator.
The MDUC register can be set by a 1-bit or 8-bit memory manipulation instruction.
<R>
Note that the overflow flag (MACOF) and sign flag (MACSF) of the multiply-accumulation result (accumulated) are
read-only flags.
Reset signal generation clears this register to 00H.
Figure 14-5. Format of Multiplication/Division Control Register (MDUC)
Address: F00E8H After reset: 00H R/W
Note 1
Symbol <7> <6> 5 4 <3> <2> <1> <0>
MDUC DIVMODE MACMODE 0 0 MDSM MACOF MACSF DIVST
DIVMODE MACMODE MDSM Operation mode selection
0 0 0 Multiplication mode (unsigned) (default)
0 0 1 Multiplication mode (signed)
0 1 0 Multiply-accumulator mode (unsigned)
0 1 1 Multiply-accumulator mode (signed)
1 0 0
Division mode (unsigned), generation of a division completion
interrupt (INTMD)
1 1 0
Division mode (unsigned), not generation of a division completion
interrupt (INTMD)
Other than above Setting prohibited
<R>
<R>
MACOF Overflow flag of multiply-accumulation result (accumulated value)
0 No overflow
1 With over flow
<Set condition>
• For the multiply-accumulator mode (unsigned)
The bit is set when the accumulated value goes outside the range from 00000000h to FFFFFFFFh.
• For the multiply-accumulator mode (signed)
The bit is set when the result of adding a positive product to a positive accumulated value exceeds
7FFFFFFFh and is negative, or when the result of adding a negative product to a negative accumulated
value exceeds 80000000h and is positive.
MACSF Sign flag of multiply-accumulation result (accumulated value)
0 The accumulated value is positive.
1 The accumulated value is negative.
Multiply-accumulator mode (unsigned): The bit is always 0.
Multiply-accumulator mode (signed): The bit indicates the sign bit of the accumulated value.
DIVST
Note 2
Division operation start/stop
0 Division operation processing complete
1 Starts division operation/division operation processing in progress
(Notes and Cautions are listed on the next page.)
R01UH0305EJ0200 Rev.2.00 658
Jul 04, 2013