MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
5-1
Chapter 5
MPC885 Instruction Set
This chapter describes the instructions implemented by the MPC885. These instructions are organized by
the level of architecture in which they are implemented—UISA, VEA, and OEA. These levels are
described in
Section 3.2.1, “Levels of the PowerPC Architecture.”
5.1
Operand Conventions
This section describes the operand conventions as they are represented in two levels of the architecture. It
also provides detailed descriptions of conventions used for storing values in registers and memory,
accessing the MPC885’s registers, and representing data in these registers.
5.1.1
Data Organization in Memory and Data Transfers
Bytes in memory are numbered consecutively starting with 0. Each number is the address of the
corresponding byte.
Memory operands may be bytes, half words, words, or double words, or, for the load/store multiple and
move assist instructions, a sequence of bytes or words. The address of a memory operand is the address of
its first byte (that is, of its lowest-numbered byte).
5.1.2
Aligned and Misaligned Accesses
The operand of a single-register memory access instruction has a natural alignment boundary equal to the
operand length. In other words, the natural address of an operand is an integer multiple of the operand
length. A memory operand is said to be aligned if it is aligned at its natural boundary; otherwise it is
misaligned.
Operands for single-register memory access instructions have the characteristics shown in
Table 5-1
.
(Although not permitted as memory operands, quad words are shown because quad-word alignment is
desirable for certain memory operands.)
Table 5-1. Memory Operands
Operand
Length
Addr[28–31] if Aligned
Byte
8 bits
xxxx
Half word
2 bytes
xxx0
Word
4 bytes
xx00
Double word
8 bytes
x000
Quad word
16 bytes
0000
Note
: An “x” in an address bit position indicates that the bit can be 0 or 1 independent of the state of other bits in the address.
Summary of Contents for PowerQUICC MPC870
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Page 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Page 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
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Page 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Page 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
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Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Page 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...