IDEC MicroSmart - Manual (Page 237)

11: B INARY A RITHMETIC I NSTRUCTIONS
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Repeat Operation in the MUL Instruction
Since the MUL (multiplication) instruction uses two destination operands, the result is stored to destination operands as
described below. Source operands S1 and S2 and destination operand D1 can be designated to repeat individually or in
combination. When destination operand D1 is not designated to repeat, the final result is set to destination operand D1 and
D1+1. When repeat is designated, consecutive operands as many as the repeat cycles starting with the designated operand
are used.
Since the repeat operation works similarly on the word and integer data types, the following examples are described using
the word data type.
Repeat One Source Operand
When only S1 (source) is designated to repeat, the final result is set to destination operands D1 and D1+1.
Repeat Destination Operand Only
When only D1 (destination) is designated to repeat, the same result is set to 6 operands starting with D1.
Repeat Two Source Operands
When S1 and S2 (source) are designated to repeat, the final result is set to destination operands D1 and D1+1.
Repeat Source and Destination Operands
When S1 (source) and D1 (destination) are designated to repeat, different results are set to 6 operands starting with D1.
Repeat All Source and Destination Operands
When all operands are designated to repeat, different results are set to 6 operands starting with D1.
I1
REP
3
S1 R
D10
D1 –
D30
D10
S1 (Repeat = 3) D1 (Repeat = 0)
S2 –
D20
S2 (Repeat = 0)
×
(D30) D20 (D31)
D11
D12
Ч
Ч
D20
D20 (D30)
D30
(D31)
D31
SOTU MUL(W)
I1
REP
3
S1 –
D10
D1 R
D30
D10
S1 (Repeat = 0) D1 (Repeat = 3)
S2 –
D20
S2 (Repeat = 0)
×
D30 D20 D31
D10
D10
Ч
Ч
D20
D20 D32
D34 D33
D35
SOTU MUL(W)
I1
REP
3
S1 R
D10
D1 –
D30
D10
S1 (Repeat = 3) D1 (Repeat = 0)
S2 R
D20
S2 (Repeat = 3)
×
(D30) D20 (D31)
D11
D12
Ч
Ч
D21
D22 (D30)
D30
(D31)
D31
SOTU MUL(W)
I1
REP
3
S1 R
D10
D1 R
D30
D10
S1 (Repeat = 3) D1 (Repeat = 3)
S2 –
D20
S2 (Repeat = 0)
×
D30 D20 D31
D11
D12
Ч
Ч
D20
D20 D32
D34 D33
D35
SOTU MUL(W)
I1
REP
3
S1 R
D10
D1 R
D30
D10
S1 (Repeat = 3) D1 (Repeat = 3)
S2 R
D20
S2 (Repeat = 3)
×
D30 D20 D31
D11
D12
Ч
Ч
D21
D22 D32
D34 D33
D35
SOTU MUL(W)