Handling Index Registers; Index Registers; Memory Areas Which Can Be Modified With Index Registers - Panasonic FP0 User Manual

FP0
8.3

Handling Index Registers

8.3.1

Index Registers

Like other registers, index registers have two points, IX and IY, for reading and writing
16-bit data.
Use an index register to indirectly specify a memory area number. (This is also called
index modification.)
Example:
Transferring the contents of data register DT100 to the number
specified by the contents of an index register.
In this example, the number of the destination data register varies depending on the
contents of IX with DT0 acting as a base. For example, when IX contains K10 the
destination will be DT10, and when IX is K20, the destination will be DT20.
In this way, index registers allow the specification of multiple memory areas with a single
instruction, and thus index registers are very convenient when handling large amounts
of data.
8.3.2

Memory Areas Which can be Modified with Index Registers

Index registers can be used to modify other types of memory areas in addition to data
registers DT.
IXWX0, IXWY1, IXWR0, IXSV0, IXEV2, IXDT100
Constants can also be modified.
IXK10, IXH1001
An index register cannot modify another index register.
IXIX, IXIY
When using index modification with an instruction which handles 32-bit data, specify
with IX. In this case, IX and IY are handled together as 32-bit data.
Higher 16-bit area
Contents of IY
R0
F0 MV, DT100, IXDT0
Base memory area.
Lower 16-bit area
Contents of IX
Precautions During Programming
8.3 Handling Index Registers
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