IDT
Operation Section Notation and Functions
79RC32355 User Reference Manual
A - 9
November 4, 2002
Notes
StoreMemory
The StoreMemory function stores a value to memory.
The specified data is stored into the physical location pAddr using the memory hierarchy (data caches
and main memory) as specified by the Cache Coherence Algorithm (CCA). The MemElem contains the
data for an aligned, fixed-width memory element (a word for 32-bit processors, a doubleword for 64-bit
processors), though only the bytes that are actually stored to memory need be valid. The low-order two (or
three) bits of pAddr and the AccessLength field indicate which of the bytes within the MemElem data should
be stored; only these bytes in memory will actually be changed.
StoreMemory (CCA, AccessLength, MemElem, pAddr, vAddr)
/* CCA:
/*
/* AccessLength: Length, in bytes, of access */
/* MemElem: Data in the width and alignment of a memory element. */
/*
The width is the same size as the CPU general */
/*
purpose register, either 4 or 8 bytes, aligned on */
/*
a 4- or 8-byte boundary. For a partial-memory-element */
/*
store, only the bytes that will be*/
/*
stored must be valid.*/
/* pAddr:
physical address */
/* vAddr:
virtual address */
Cache Coherence Algorithm, the method used to access */
caches and memory and resolve the reference. */
Prefetch
The Prefetch function prefetches data from memory.
Prefetch is an advisory instruction for which an implementation-specific action is taken. The action taken
may increase performance but must not change the meaning of the program or alter architecturally visible
state.
Prefetch (CCA, pAddr, vAddr, DATA, hint)
/* CCA:
/*
/* pAddr:
/* vAddr:
/* DATA:
/* hint:
Cache Coherence Algorithm, the method used to access */
caches and memory and resolve the reference. */
physical address */
virtual address */
Indicates that access is for DATA */
hint that indicates the possible use of the data */
endfunction Prefetch
Table A.1 lists the data access lengths and their labels for loads and stores.
Miscellaneous Functions
This section lists miscellaneous functions not covered in previous sections.
AccessLength Name
Value
Meaning
WORD
3
4 bytes (32 bits)
TRIPLEBYTE
2
3 bytes (24 bits)
HALFWORD
1
2 bytes (16 bits)
BYTE
0
1 byte (8 bits)
Table A.1 AccessLength Specifications for Loads/Stores