Computer Hardware User's Guide

CPU Multiport Register File
3-2
3.1 CPU Multiport Register File
The ’C3x provides 28 registers in a multiport register file that is tightly coupled to
the CPU. The program counter (PC) is not included in the 28 registers. All of these
registers can be operated on by the multiplier and the ALU and can be used as
general-purpose 32-bit registers.
Table 3–1 lists the registers’ names and assigned functions of the ’C3x.
Table 3–1. CPU Registers
Register
Symbol
Register
Machine
Value (hex)
Assigned Function Name Section Page
R0 00 Extended-precision register 0 3.1.1 3-3
R1 01 Extended-precision register 1 3.1.1 3-3
R2 02 Extended-precision register 2 3.1.1 3-3
R3 03 Extended-precision register 3 3.1.1 3-3
R4 04 Extended-precision register 4 3.1.1 3-3
R5 05 Extended-precision register 5 3.1.1 3-3
R6 06 Extended-precision register 6 3.1.1 3-3
R7 07 Extended-precision register 7 3.1.1 3-3
AR0 08 Auxiliary register 0 3.1.2 3-4
AR1 09 Auxiliary register 1 3.1.2 3-4
AR2 0A Auxiliary register 2 3.1.2 3-4
AR3 0B Auxiliary register 3 3.1.2 3-4
AR4 0C Auxiliary register 4 3.1.2 3-4
AR5 0D Auxiliary register 5 3.1.2 3-4
AR6 0E Auxiliary register 6 3.1.2 3-4
AR7 0F Auxiliary register 7 3.1.2 3-4
DP 10 Data-page pointer 3.1.3 3-4
IR0 11 Index register 0 3.1.4 3-4
IR1 12 Index register 1 3.1.4 3-4
BK 13 Block-size register 3.1.5 3-4
SP 14 System-stack pointer 3.1.6 3-4
ST 15 Status register 3.1.7 3-5
IE 16 CPU/DMA interrupt-enable 3.1.8 3-9
IF 17 CPU interrupt flags 3.1.9 3-11
IOF 18 I/O flags 3.1.10 3-16
RS 19 Repeat start-address 3.1.11 3-17
RE 1A Repeat end-address 3.1.11 3-17
RC
1B Repeat counter 3.1.11 3-17