
380 EMBEDDED SYSTEMS
10.18.3.2 | Post-indexed Addressing Mode
In this mode, the eff ective address calculation is done after the execution of the specifi c
instruction has been done.
Take the case of the instruction LDR R0, [R4], #4
Here the data pointed by the content of R4 is fi rst copied to R0. After that, the
content of R4 is changed to R4 + 4. ere is no need of the ‘!’ operation because that is
exactly what post-indexing does.
Example 10.14
Let’s add 10 numbers which are in memory. e numbers are 16-bit long, that is, half
words, and use two byte spaces. e pre-indexed mode of addressing with write back is
used to index the half words which ...