dsp56800e Freescale Semiconductor, Inc, dsp56800e Datasheet - Page 93

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

3.6.5.2
In this addressing mode, the instruction specifies only the 6 LSBs of the effective address. The upper 18
bits are hard-wired to a specific area of memory, which varies depending on the specific implementation of
the chip. This scheme allows efficient access to a 64-location area in data memory, which may be
dedicated to on-chip peripheral registers.
Figure 3-31 demonstrates the I/O short addressing mode. Note the use of the assembler forcing operator
(<<) in this example, indicating that the I/O short addressing mode is in use (see Table 3-13 on page 3-26).
Freescale Semiconductor
Available for: Word
Assembler Syntax: X:<<pp
Additional Instruction Execution Cycles: 0
Additional Effective Address Program Words: 0
I/O Short Address: <<pp
$00FFFB
$00FFFF
R3
Figure 3-31. Absolute Addressing: 6-Bit I/O Short Address
15
15
5
Before Execution
X Memory
I/O Short Address Example:
6
XXXX
7
Data Types and Addressing Modes
8
0
0
MOVEU.W X:<<$FFFB,R3
$00FFFB
$00FFFF
R3
15
15
5
After Execution
X Memory
6
$5678
7
8
Addressing Modes
0
0
3-43