XC2200 Derivatives
System Units (Vol. 1 of 2)
Central Processing Unit (CPU)
User’s Manual
4-29
V2.1, 2008-08
CPUSV2_X, V2.2
4.5
Use of General Purpose Registers
The CPU uses several banks of sixteen dedicated registers R0, R1, R2, … R15, called
General Purpose Registers (GPRs), which can be accessed in one CPU cycle. The
GPRs are the working registers of the arithmetic and logic units and many also serve as
address pointers for indirect addressing modes.
The register banks are accessed via the 5-port register file providing the high access
speed required for the CPU’s performance. The register file is split into three
independent physical register banks. There are
two types of register banks
:
•
Two local register banks
which are a part of the register file
•
A global register bank
which is memory-mapped and cached in the register file
Figure 4-5
Register File
R15
MCD04873
R15
R14
R13
R12
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
R15
R14
R13
R12
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
Core-RAM
Global
Local
R15
R0
Memory
mapped
GPR Bank
AGU Write Port
ALU Write Port
AGU Read Port
ALU Read Port 1
ALU Read Port 2
Registerfile
CP