15
15 – 46
rounding is unbiased, except on the ADSP-217x, ADSP-218x, and ADSP-
21msp58/59 processors, which offer a biased rounding mode. For a
discussion of biased vs. unbiased rounding, see “Rounding Mode” in the
“Multiplier/Accumulator” section of Chapter 2, Computation Units.
Status Generated:
ASTAT:
7
6
5
4
3
2
1
0
SS
MV AQ AS
AC AV AN AZ
–
*
–
–
–
–
–
–
MV
Set on MAC overflow (if any of the upper 9 bits of MR are
not all one or zero). Cleared otherwise.
Instruction Format:
(xop * yop) Conditional ALU/MAC Operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 0 1 0 0 Z AMF Yop Xop 0 0 0 0 COND
AMF: Specifies the ALU or MAC Operation. In this case,
AMF
FUNCTION
Data Format
X-Operand
Y-Operand
0 1 1 0 0
MR–xop * yop
(SS)
Signed
Signed
0 1 1 0 1
MR–xop * yop
(SU)
Signed
Unsigned
0 1 1 1 0
MR–xop * yop
(US)
Unsigned
Signed
0 1 1 1 1
MR–xop * yop
(UU)
Unsigned
Unsigned
0 0 0 1 1
MR–xop * yop
(RND)
Signed
Signed
Z: Destination register
Yop: Y operand register
Xop: X operand register
COND: condition
(xop * xop) Conditional ALU/MAC Operation, Instruction Type 9:
(ADSP-217x, ADSP-218x, ADSP-21msp58/59 only)
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 0 1 0 0 Z AMF 0 0 Xop 0 0 0 1 COND
AMF: Specifies the ALU or MAC Operation. In this case,
AMF
FUNCTION
Data Format
X-Operand
0 1 1 0 0
MR–xop * xop
(SS)
Signed
0 1 1 1 1
MR–xop * xop
(UU)
Unsigned
0 0 0 1 1
MR–xop * xop
(RND)
Signed
MAC
MULTIPLY / SUBTRACT