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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Developer’s Manual
Order Number: 306262-004US
97
Intel XScale
®
Processor—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
The format of LDC and STC for CP14 is shown in
. LDC and STC follow the
programming notes in the ARM* Architecture Reference Manual. Note that access to
CP15 with LDC and STC will cause an undefined exception.
LDC and STC transfer a single 32-bit word between a coprocessor register and
memory. These instructions do not allow the programmer to specify values for
opcode_1, opcode_2, or Rm; those fields implicitly contain zero, which means the
performance monitoring registers are not accessible.
Table 9.
MRC/MCR Format
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
cond
1 1 1 0
opcode_1
n
CRn
Rd
cp_num
opcode_2
1
CRm
Bits
Description
Notes
31:28
cond - Intel
®
StrongARM
*
condition codes
-
23:21
opcode_1 - Reserved
Should be programmed to zero for future
compatibility
20
n - Read or write coprocessor register
0 = MCR
1 = MRC
-
19:16
CRn - specifies which coprocessor register
-
15:12
Rd - General-Purpose Register, R0..R15
-
11:8
cp_num - coprocessor number
Intel XScale
®
Processor defines three
coprocessors:
0b1111 = CP15
0b1110 = CP14
0x0000 = CP0
Note:
Mappings are implementation defined
for all coprocessors below CP14 and
above CP0. Access to unimplemented
coprocessors (as defined by the
cpConfig bus) cause exceptions.
7:5
opcode_2 - Function bits
This field should be programmed to zero for
future compatibility unless a value has been
specified in the command.
3:0
CRm - Function bits
This field should be programmed to zero for
future compatibility unless a value has been
specified in the command.
Table 10.
LDC/STC Format when Accessing CP14 (Sheet 1 of 2)
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
cond
1 1 0 P U N W L
Rn
CRd
cp_num
8_bit_word_offset
Bits
Description
Notes
31:28
cond - Intel
®
StrongARM
*
condition codes
-
24:23,21
P, U, W - specifies 1 of 3 addressing modes
identified by addressing mode 5 in the ARM*
Architecture Reference Manual.
-
22
N - should be 0 for CP14 coprocessors. Setting
this bit to 1 has will have an undefined effect.
20
L - Load or Store
0 = STC
1 = LDC
-