Cpu Registers; C28X With Floating-Point Registers - Texas Instruments TMS320C28 series Reference Manual

CPU Registers

2.1 CPU Registers
Devices with the C28x+FPU include the standard C28x register set plus an additional set of floating-point
unit registers. The additional floating-point unit registers are the following:
• Eight floating-point result registers, RnH (where n = 0 - 7)
• Floating-point Status Register (STF)
• Repeat Block Register (RB)
All of the floating-point registers except the repeat block register are shadowed. This shadowing can be
used in high priority interrupts for fast context save and restore of the floating-point registers.
Figure 2-1 shows a diagram of both register sets and
information on the standard C28x register set, see the TMS320C28x DSP CPU and Instruction Set
Reference Guide (literature number SPRU430).
Standard C28x Register Set
14 CPU Register Set
Figure 2-1. C28x With Floating-Point Registers
ACC (32-bit)
P (32-bit)
XT (32-bit)
XAR0 (32-bit)
XAR1 (32-bit)
XAR2 (32-bit)
XAR3 (32-bit)
XAR4 (32-bit)
XAR5 (32-bit)
XAR6 (32-bit)
XAR7 (32-bit)
PC (22-bit)
RPC (22-bit)
DP (16-bit)
SP (16-bit)
ST0 (16-bit)
ST1 (16-bit)
IER (16-bit)
IFR (16-bit)
DBGIER (16-bit)
Table 2-1 shows a register summary. For
Additional 32-bit FPU Registers
R0H (32-bit)
R1H (32-bit)
R2H (32-bit)
R3H (32-bit)
R4H (32-bit)
R5H (32-bit)
R6H (32-bit)
R7H (32-bit)
FPU Status Register (STF)
Repeat Block Register (RB)
FPU registers R0H - R7H and STF
are shadowed for fast context
save and restore
SPRUEO2A – June 2007 – Revised August 2008
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