The Thumb instruction set is a subset of the most commonly used bit ARM instructions. Thumb instructions are each 16 bits long, and have a corresponding bit ARM instruction that has the same effect on the processor model.
Thumb instructions operate with the standard ARM register configuration, allowing excellent interoperability between ARM and Thumb states. On execution, bit Thumb instructions are transparently decompressed to full bit ARM instructions in real time, without performance loss.
Thumb therefore offers a long branch range, powerful arithmetic operations, and a large address space. Thumb, therefore, makes the ARM7TDMI core ideally suited to embedded applications with restricted memory bandwidth, where code density and footprint is important.
The availability of both bit Thumb and bit ARM instruction sets gives designers the flexibility to emphasize performance or code size on a subroutine level, according to the requirements of their applications. For example, critical loops for applications such as fast interrupts and DSP algorithms can be coded using the full ARM instruction set then linked with Thumb code. The Thumb instruction set.
Thumb instruction set in ARM - Embedded Systems - Lec-15 - Bhanu priya
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