Analog Devices ADSP-BF53x Blackfin Reference page 804

Introduction
Notation Conventions
This appendix uses the following conventions:
• Register names are alphabetic, followed by a number in cases where
there are more than one register in a logical group. Thus, examples
include ASTAT, FP, R3, and M2.
Register names are reserved and may not be used as program
identifiers.
• Some operations require a register pair. Register pairs are always Data
Registers and are denoted using a colon, for example, R3:2. The
larger number must is written first. Note: The hardware supports
only odd-even pairs, for example, R7:6, R5:4, R3:2, and R1:0.
• Some instructions require a group of adjacent registers. Adjacent reg-
isters are denoted by the range enclosed in brackets, e.g., R[7:3].
Again, the larger number appears first.
• Portions of a particular register may be individually specified. This is
written with a dot (".") following the register name, then a letter
denoting the desired portion. For 32-bit registers, ".H" denotes the
most significant ("High") portion, ".L" denotes the least significant
portion. The subdivisions of the 40-bit registers are described later.
Register names are reserved and may not be used as program identifiers.
C-4 ADSP-BF53x/BF56x Blackfin Processor Programming Reference