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CHAPTER 2 DEPENDENCE FUNCTIONS
2.2.4 On-the-fly Memory Access
While on-the-fly, the area mapped to the emulation memory is Read/Write enabled, but
the area mapped to the user memory area is Read-only enabled.
■ Read/Write Memory while On-the-fly
The user memory cannot be accessed while on-the-fly (when execute the MCU). However, the emulation
memory can be accessed. (The using cycle-steal algorithm eliminates any negative effect on the MCU
speed.)
This emulator allows the user to use part of the emulation memory as a mirror area. The mirror area holds a
copy of the user memory. Using this mirror area makes the Read-only enabled function available while on-
the-fly.
Each memory area operates as follows:
- User Memory Area
Access to the user memory is permitted only when the operation is suspended by a break.
- Emulation Memory Area
Access to the emulation memory is permitted regardless of whether the MCU is suspended, or while on-
the-fly.
- Mirror Area
The emulation memory with the MIRROR setting can be set up for the user memory area to be referred to
while on-the-fly. This area is specifically called the mirror area.
As shown in Figure 2.2-1, the mirror area performs access to the user memory while the MCU is stopped,
and such access is reflected simultaneously in the emulation memory specified as the mirror area. (Read
access is also reflected in the emulation memory specified as the mirror area).
In addition, as shown in Figure 2.2-2, access to the user memory by the MCU is reflected "as it is" in the
emulation memory of the mirror area.
While on-the -fly, the user memory cannot be accessed. However, the emulation memory specified as the
mirror area can be read instead. In other words, identical data to that of the user memory can be read by
accessing the mirror area.
However, at least one time access must be allowed before the emulation memory of the mirror area has
the same data as the user memory. The following copy types allow the emulation memory of the mirror
area to have the same data as the user memory.
(1) Copying all data when setting mirror area
When, /COPY is specified with the mirror area set using the SET MAP command, the whole area is
specified, as the mirror area is copied.
(2) Copying only required portion using memory access commands
Data in the specified portion can be copied by executing a command that accesses memory.