I have Asked a near question few days ago but I am still confused about the following :
I know that there is ARM Instruction set which is all 32-bit wide Encoding
but for thumb and thumb-2 comes the confusion:
1) thumb : for each 16 bit instruction there is an ARM (32-bit Encoding) with corresponding functionality BUT : Does THUMB contain 32-bit encoded instructions in addition to those 16-bit instructions .... if yes do they have Similar Encoding like ARM or Totally different ?
2) I understand That thumb-2 added some new 16-bit and 32-bit instructions .... is that the only difference between Thumb and Thumb2 ?
please tell the reference for ur answer
The encodings of Thumb2 and ARM ISAs are totally different.
ARM and Thumb have instructions with the same functionality and assembler mnemonics but different encodings.
Thumb2 is a superset of Thumb.
I'm not sure there is a modern reference for this as the architecture describes Thumb as a single instruction set with certain groups of instructions being optional.
Look at page 6 of this guide for more on Thumb2
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