STM8 addressing modes |
PM0044 |
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6.6Short Pointer Indirect Long addressing mode
The pointer address is a byte, the pointer size is a word, thus allowing up to 128 KB addressing space, and requires 1 byte after the op-code.
Example: |
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0040 |
42E5 |
ptr |
dc.w |
var |
0409 |
92C640 |
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LD |
A,[shortptr.w] |
42E5 |
11 |
var |
dc.b |
$11 |
Action: |
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A = [shortptr.w] = ((shortptr.w)) = (($40.w)) = ($42E5) = $11
Figure 16. Short Pointer Indirect Long addressing mode example
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Before Completion |
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0040 |
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A |
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ptr .word var |
42 |
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E5 |
0041 |
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Previous Value |
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PC |
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LD A, [shortptr.w] |
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0409 |
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0409 |
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040A |
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C6 |
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040B |
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40 |
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040C |
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Steps to determine Effective Address
PC = 0409
PC = PC + 2 = 40B EA = ((PC)) :((PC)+1)
= 42E5
var.byte 0x011 |
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42E5 |
EA |
42E5 |
11 |
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After Completion
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Instruction Complete |
ptr .word var |
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0040 |
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42 |
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0041 |
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A = (EA) = 0x11 |
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E5 |
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New PC = PC +1 = 040C |
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LD A, [shortptr.w] |
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0409 |
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040A |
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040B |
New PC |
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40 |
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040C |
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040C |
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A |
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var .byte 0x011 |
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42E5 |
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0x11 |
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11 |
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46/162 |
Doc ID 13590 Rev 3 |