XC2200 Derivatives
System Units (Vol. 1 of 2)
Central Processing Unit (CPU)
User’s Manual
4-48
V2.1, 2008-08
CPUSV2_X, V2.2
Figure 4-15 Arithmetic MAC Operations and Addressing via the IDX Pointers
Table 4-21
Generating Physical Addresses from Indirect Pointers (IDXx)
Step Executed Action
Calculation
Notes
1
Determine the used IDXx
pointer
---
–
2
Calculate an intermediate
long address for the parallel
data move operation and
in/decrement indirect
pointer (‘IDXx
±
’) by 2
(
∆
= 2), or depending on
offset registers (
∆
= QXx)
Interm. Addr. =
(IDXx Address)
± ∆
Optional step, executed only if
required by instruction
CoXXXM and addressing
mode
3
Calculate long 16-bit
address
Long Address =
(IDXx Pointer)
–
4
Calculate the physical 24-bit
address using the resulting
pointer
Physical Addr. =
Page/S
Pointer offset
Uses DPPs or page/segment
override mechanisms, see
5
Post-in/decrement indirect
pointer (‘IDXx
±
’) by 2
(
∆
= 2), or depending on
offset registers (
∆
= QXx)
(IDXx Pointer) =
(IDXx Pointer)
± ∆
Optional step, executed only if
required by addressing mode
0
23
0
2
MCA04926
16-Bit IDX Pointer
15
12
Memory
02'0000
H
11
11
01'0000
H
00'0000
H
DPRAM in Data Page 3
1
0
1
0
1
1
1
0
0
0
0
0
0
15
12
0