Multiply With Internal Accumulate Format - Intel IXP45X Developer's Manual

Intel
Two new instruction formats were added for coprocessor 0: Multiply with Internal
Accumulate Format and Internal Accumulate Access Format. The formats and
instructions are described next.
3.8.3.1.1

Multiply with Internal Accumulate Format

A new multiply format has been created to define operations on 40-bit accumulators.
Table 9, "MRC/MCR Format" on page 97
code for this format lies within the coprocessor register transfer instruction type. These
instructions have their own syntax.
Table 65. Multiply with Internal Accumulate Format
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
cond
Bits
31:28
19:16
15:12
7:5
3:0
Two new fields were created for this format, acc and opcode_3. The acc field specifies
one of eight internal accumulators to operate on and opcode_3 defines the operation
for this format. The Intel XScale processor defines a single 40-bit accumulator referred
to as acc0; future implementations may define multiple internal accumulators. The
Intel XScale processor uses opcode_3 to define six instructions, MIA, MIAPH, MIABB,
MIABT, MIATB and MIATT.
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1 1 1 0 0 0 1 0
Description
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cond - Intel StrongARM
opcode_3 - specifies the type of multiply with
internal accumulate
Rs - Multiplier
acc - select 1 of 8 accumulators
Rm - Multiplicand
shows the layout of the new format. The op
opcode_3 Rs
*
condition codes -
Intel XScale processor defines the following:
0b0000 =
0b1000 =
0b1100 =
0b1101 =
0b1110 =
0b1111 =
The effect of all other encodings are
unpredictable.
Intel XScale processor only implements acc0;
access to any other acc has unpredictable
effect.
-
®
8 7 6 5 4 3
0 0 0 0 acc 1
Notes
MIA
MIAPH
MIABB
MIABT
MIATB
MIATT
August 2006
Order Number: 306262-004US
Processor
2 1 0
Rm