dsp56800e Freescale Semiconductor, Inc, dsp56800e Datasheet - Page 58

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

Data Types and Addressing Modes
3.3
The DSP56800E core implements a powerful set of memory-access operations that eases the task of
programming the CPU, decreases program code size, improves efficiency, and decreases the power
consumption and processing power that are required to perform a given task.
Memory is accessed in a variety of ways. Examples include the following types of instructions:
Each of these memory accesses can be performed both on different sizes of data and with a number of
different addressing modes. Byte, word, and long-word memory accesses, on both signed and unsigned
data, are supported. The provided addressing modes make it easy to access memory quickly and
efficiently.
3.3.1
The DSP56800E supports memory moves to and from both data and program memory, multiple data sizes,
and a variety of addressing modes. Understanding the syntax for each of these options is essential to
understanding and taking advantage of this flexibility.
3-8
•
•
•
Move instructions that access data or program memory
Arithmetic or bit-manipulation instructions where one operand is located in data memory
Parallel move instructions that perform an operation and move data to or from memory
simultaneously
Memory Access Overview
Move Instruction Syntax
Representation
$F E000 0000
$F C000 0000
$2 0000 0000
$0 8000 0000
$0 4000 0000
$0 2000 0000
$0 0000 0000
$F 8000 0000
$E 0000 0000
Hexadecimal
Table 3-3. Interpretation of 36-Bit Data Values
DSP56800E Core Reference Manual
Entire Accumulator
36-Bit Integer in
–1073741824
–2147483648
–8589934592
8589934592
2147483648
1073741824
–536870912
536870912
0
Decimal Representation
16-Bit Integer in MSP of
Accumulator
(Overflows)
(Overflows)
(Overflows)
–16384
–32768
16384
–8192
8192
0
Freescale Semiconductor
Fraction
–0.25
–0.5
–4.0
0.25
–1.0
4.0
1.0
0.5
0.0