Data Sheet
June 2001
DSP16410B Digital Signal Processor
Agere Systems Inc.
Agere Systems—Proprietary
Use pursuant to Company instructions
233
6 Software Architecture
(continued)
6.2 Registers
(continued)
6.2.3 Register Encodings
(continued)
Table 141. auc0 (Arithmetic Unit Control 0) Register
15—14
13—11
Reserved
10
9
8
7
6
5—4
3—2
1—0
P1SHFT[1:0]
FSAT
SHFT15
RAND
X=Y=
YCLR
ACLR[1:0]
ASAT[1:0]
P0SHFT[1:0]
Bit
Field
Value
Description
R/W
Reset
Value
00
15—14
P1SHFT[1:0]
00
01
10
11
0
0
1
p1
not shifted.
p1
>>2.
p1
<<2.
p1
<<1.
Reserved—write with zero.
Disabled when zero.
Enable 32-bit saturation for the following results: the scaled out-
puts of the
p0
and
p1
registers, the intermediate result of the
3-input ADDER
, and the results of the ALU/ACS, ADDER/ACS,
and BMU.
p1
>>15 in F1E operations performs normally.
To support GSM-EFR,
p1
>>15 in F1E operations actually per-
forms (
p1
>>16)<<1 clearing the least significant bit.
Enable pseudorandom sequence generator (PSG).
Reset and disable pseudorandom sequence generator (PSG).
Normal operation.
Data transfer statements that load the
y
register also load the
x
register with the same value.
§
The DAU clears
yl
if it loads
yh
.
The DAU leaves
yl
unchanged if it loads
yh
.
The DAU clears
a1l
if it loads
a1h
.
The DAU leaves
a1l
unchanged if it loads
a1h
.
The DAU clears
a0l
if it loads
a0h
.
The DAU leaves
a0l
unchanged if it loads
a0h
.
Enable
a1
saturation
on 32-bit overflow.
Disable
a1
saturation on 32-bit overflow.
Enable
a0
saturation
on 32-bit overflow.
Disable
a0
saturation on 32-bit overflow.
p0
not shifted.
p0
>>2.
p0
<<2.
p0
<<1.
R/W
13—11
10
Reserved
FSAT
R/W
R/W
R/W
0
0
0
§
Saturation takes effect only if the ADDER has three input operands and there is no ALU/ACS operation in the same instruction.
After re-enabling the PSG by clearing RAND, the program must wait one instruction cycle before testing the heads or tails condition.
The following apply:
Instructions that explicitly load any part of the
x
register (i.e.,
x
,
xh
, or
xl
) take precedence over the X=Y= mode.
Instructions that load
yh
(but not
x
or
xh
) load
xh
with the same data. If YCLR is zero, the DAU clears
yl
and
xl
.
Instructions that load
yl
load
xl
with the same data and leave
yh
and
xh
unchanged.
If enabled, 32-bit saturation of the accumulator value occurs if the DAU stores the value to memory or to a register. Saturation also applies if the DAU
stores the low half, high half, or guard bits of the accumulator. There is no change to the contents stored in the accumulator; only the value stored to
memory or a register is saturated.
9
SHFT15
0
1
R/W
0
8
RAND
0
1
0
1
R/W
0
7
X=Y=
R/W
0
6
YCLR
0
1
0
1
0
1
0
1
0
1
00
01
10
11
R/W
0
5
ACLR[1]
R/W
0
4
ACLR[0]
R/W
0
3
ASAT[1]
R/W
0
2
ASAT[0]
R/W
0
1—0
P0SHFT[1:0]
R/W
00