9.2.3
LDI/TDI: Loading to or
Transferring from a 32-Bit
Memory Area Indirectly
The following table shows which register names you can use on the
CPU 948 for the LDI and TDI operations and how these are assigned.
Register name Register assignment (each 32 bits wide)
A1 ACCU 1 (ACCU1, bits 0 to 31)
1)
A2 ACCU 2 (ACCU1, bits 0 to 31)
SA STEP address counter (bits 0 to 19)
BA BA register (block start address, bits 0 to 19)
BR BR register (base address register, bits 0 to 19)
1)
Loading the contents of an addressed memory register into the A1 register overwrites
the address stored in ACCU 1.
Byte addresses
If you reference byte addresses with the LDI or TDI operations, note
the following:
•• the LDI operation overwrites the high byte of the register with non-
defined values (except for flags, PIQ, PII; with these areas, FFH is
written in the high byte)
and
•• the TDI operation transfers only the low bytes of the register (the
high bytes are lost – refer to the example on the following page
Data storage with LDI/TDI
Table 9-3 32-bit register for LDI/TDI
High register
Low register
31
16
15
15
DW n
Address
DW n+1
0
0
aaaa
aaaa
bbbb
bbbb
Memory Access via Address in ACCU 1
CPU 948 Programming Guide
C79000-G8576-C848-04
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