PM0044 |
STM8 addressing modes |
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6.4Indexed addressing mode (No Offset, Short, SP, Long, Extended)
Table 24. |
Overview Indexed addressing mode instructions |
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Addressing mode |
Syntax |
EA formula |
Ptr Adr |
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Ptr Size |
Dest adr |
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No offset |
Direct |
Indexed |
(ndx) |
(ndx) |
--- |
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--- |
00..FFFF |
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Short |
Direct |
Indexed |
(shortoff,ndx) |
(ptr + ndx) |
op + 1 |
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Byte |
00..100FE |
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Stack |
Direct |
Indexed |
(shortoff,SP) |
(ptr + SP) |
op + 1 |
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Byte |
00..(FF+stacktop) |
Pointer |
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Long |
Direct |
Indexed |
(longoff,ndx) |
(ptr.w + ndx) |
op + 1..2 |
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Word |
000000..01FFFE |
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Extended |
Direct |
Indexed |
(extoff,ndx) |
(ptr.e + ndx) |
op + 1..3 |
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Ext Word |
000000..FFFFFF |
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The data byte required for operation is found by its memory address, which is defined by the unsigned addition of an index register (X or Y or SP) with an offset which follows the opcode.
The indexed addressing mode is made of five sub-modes:
Table 25. No Offset, Long, Short and SP Indexed instructions |
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Instructions |
Functions |
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LD, LDW |
Load |
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CLR |
Clear |
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CP |
Compare |
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AND, OR, XOR |
Logical Operations |
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ADC, ADD, SUB, SBC, ADDW, SUBW |
Arithmetic Addition/Subtraction operations |
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INC, DEC |
Increment/Decrement |
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TNZ |
Test Negative or Zero |
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CPL, NEG |
1’s or 2’s Complement |
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SLA, SLL, SRL, SRA, RLC, RRC |
Shift and Rotate Operations |
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SWAP |
Swap Nibbles |
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Table 26. |
No Offset, Long, Short Indexed Instructions |
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Instructions |
Functions |
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CALL, JP |
Call or Jump subroutine |
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Table 27. |
Extended Indexed Instructions only |
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Instructions |
Functions |
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LDF |
Far Load |
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Doc ID 13590 Rev 3 |
39/162 |