UM0144 datasheet(8/92 Pages) STMICROELECTRONICS

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2 ST7 Addressing Modes

ST7 Assembler Linker

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UM0144

ST7 Addressing Modes

2.1

Overview of ST7 addressing modes

The ST7 assembler instruction set incorporates the following different addressing modes:

All ST7 addressing modes are described in full detail, with specific examples, in the

ST7 Family

8-bit MCUs Programming Manual. This chapter seeks only to give a brief explanation of the

main addressing mode types.

2.2

General instruction syntax

The ST7 instruction set provide a single source-coding model regardless of which components

are operands—the accumulator (A), an index register (X or Y), an 8-bit stack pointer (S) for

ST7, the condition code register (CC), or a memory location. For example, a single instruction,

, originates register to register transfers as well as memory to accumulator data movements.

Table 2.

ST7 Addressing modes

Instruction Set

Addressing Mode

Example

ST7

Inherent

nop

Immediate

ld A,#$F5

Direct (short address)

ld A,$F5

Direct (long address)

ld A,$F5C2

X or Y Indexed (no offset)

ld A,(X)

X or Y Indexed (short offset)

ld A,($F5,X)

X or Y Indexed (long offset)

ld A,($F5C2,X)

Short Pointer Indirect (short pointed data)

ld A,[$F5]

Short Pointer Indirect (long pointed data)

ld A,[$F5.w]

Short Pointer Indirect (short pointed data) X

or Y Indexed

ld A,([$F5],X)

Short Pointer Indirect (long pointed data) X or

Y Indexed

ld A,([$F5.w],X)

Direct Relative (short offset)

jrt $F5

Short Pointer Indirect Relative (short pointed

data)

jrt [$F5]

Bit operation

bset byte, #5

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