Multiply With Internal Accumulate Format; Multiply With Internal Accumulate Format - Intel XScale Core Developer's Manual

Intel XScale® Core Developer's Manual
Programming Model
2.3.1.1

Multiply With Internal Accumulate Format

A new multiply format has been created to define operations on 40-bit accumulators.
"Multiply with Internal Accumulate Format" on page 2-24
The opcode for this format lies within the coprocessor register transfer instruction type. These
instructions have their own syntax.
Table 2-1.

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 1 of 8
internal accumulators to operate on and opcode_3 defines the operation for this format. The Intel
®
XScale
define multiple internal accumulators. The Intel XScale
instructions, MIA, MIAPH, MIABB, MIABT, MIATB and MIATT.
24
1 1 1 0 0 0 1 0
Description
cond - ARM condition codes
opcode_3 - specifies the type of multiply with
internal accumulate
Rs - Multiplier
acc - select 1 of 8 accumulators
Rm - Multiplicand
core defines a single 40-bit accumulator referred to as acc0; future implementations may
January, 2004
shows the layout of the new format.
opcode_3 Rs 0 0 0 0
-
The Intel XScale
0b0000 =
0b1000 =
0b1100 =
0b1101 =
0b1110 =
0b1111 =
The effect of all other encodings are
unpredictable.
The Intel XScale
access to any other acc has an unpredictable
effect.
-
®
core uses opcode_3 to define six
Table 2-1,
8 7 6 5 4 3 2
acc 1
Notes
®
core defines the following:
MIA
MIAPH
MIABB
MIABT
MIATB
MIATT
®
core only implements acc0;
Developer's Manual
1 0
Rm