C166SV2 Datasheet, PDF (56/438 Pages) Infineon Technologies AG – 16-Bit Microcontroller

User Manual
C166S V2
Central Processing Unit
2.5.3 DSP Addressing
In addition to the Standard Address Generation Unit, the DSP Address Generation Unit
provides an additional set of pointer and offset registers. An independent arithmetic unit
allows the update of these dedicated pointer registers in parallel with the GPR-Pointer
modification of the Standard Address Generation Unit. The DSP Address Generation
Unit only supports indirect addressing modes that use the special pointer registers IDX0
and IDX1.
The Pointer Register IDX0 and IDX1
The additional set of pointer registers IDX0 and IDX1 allows the execution of DSP
specific CoXXX instruction in one CPU cycle.
IDX0
Address Pointer
SFRb
Reset Value: 0000_H
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
IDX
0
rw
r
IDX1
Address Pointer
SFRb
Reset Value: 0000_H
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
IDX
0
rw
r
Field
IDX
0
Bits Type Description
[15:1] rw
Modifiable portion of register IDXx
Specifies the 16-bit value of a dedicated address
pointer.
[0] r
Fixed to 0
Note: During the initialization of the IDX registers, instruction flow stalls are possible. For
the proper operation, refer to the Section 4.1.4.
The address pointers can be used for arithmetic operations as well as for the special
CoMOV instruction. But, the generation of the 24 bit memory address is different.
In case of arithmetic CoXXX operations, the IDX pointers are automatically zero
extended to a 24-bit memory address. The IDX address pointers should point to the
internal DPRAM area. Even if the IDX address pointers do not point to the internal
User Manual
2-56
V 1.7, 2001-01