dsp56800e Freescale Semiconductor, Inc, dsp56800e Datasheet - Page 104

• Manufacturer Part Number: dsp56800e
• Description: 16-bit Digital Signal Controller Core
• Manufacturer: Freescale Semiconductor, Inc

Instruction Set Introduction
4.1.6
The bit-manipulation instructions are used to test or modify a set of one or more bits, called a bitfield,
within a word. They can operate on any data memory location, peripheral, or register. The carry bit in the
status register is the only condition code affected by these instructions. They all execute in 2, 3, or 4
instruction cycles.
For similar instructions that change execution flow based on a bitfield test, see Section 4.1.9, “Program
Control Instructions.”
Table 4-6 lists the bit-manipulation instructions.
Using the bit-manipulation instructions to modify AGU registers (Rn, N, SP, or M01) can result in pipeline
dependencies. See Section 10.4.2, “AGU Pipeline Dependencies,” on page 10-28 for more information.
4.1.7
The looping instructions are used to perform program looping with minimal overhead. The DSP56800E
architecture supports efficient hardware looping on a single instruction (using REP) or on a block of
instructions (using DO). Using these instructions can dramatically increase the performance of iterative
algorithms. For a full discussion of hardware looping and the looping instructions, see Section 8.5,
“Hardware Looping,” on page 8-18.
Table 4-7 lists the loop instructions.
4.1.8
The move instructions transfer data between core registers and memory or peripherals, or between two
memory or peripheral locations. Move instructions that write an accumulator register to memory or a
peripheral can also automatically saturate, limiting the value written. In addition to the following move
4-8
Bit-Manipulation Instructions
Looping Instructions
Move Instructions
Instruction
ENDDO
DOSLC
REP
Instruction
DO
BFTSTH
BFTSTL
BFCHG
BFCLR
BFSET
Load LC register with unsigned 16-bit loop count and start hardware loop
Start hardware loop with signed 16-bit loop count already in LC register
Terminate current hardware DO loops
Repeat immediately following instruction
DSP56800E Core Reference Manual
Table 4-7. Looping Instructions
Bitfield test and change
Bitfield test and clear
Bitfield test and set
Bitfield test for on condition
Bitfield test for off condition
Table 4-6. Bitfield Instructions
Description
Description
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