Sinopsis
A computer program is usually defined as a sequence of instructions that act on data and return an expected result. In a high-level language, the sequence and data are described in a symbolic, abstract form. It is necessary to use a compiler to translate them into machine language instructions, which are only understood by the processor. Assembly language is directly derived from machine language, so when programming in assembly language the programmer is forced to see things from the point of view of the processor.
When executing a program, a computer processor obeys a series of numerical orders – instructions – that are read from memory: these instructions are encoded in binary form. The collection of instructions in memory makes up the code of the program being executed. Other areas of memory are also used by the processor during the execution of code: an area containing the data (variables, constants) and an area containing the system stack, which is used by the processor to store, for example, local data when calling subprograms. Code, data and the system stack are the three fundamental elements of all programs during their execution.
It is possible to program directly in machine language – that is, to write the bit instruction sequences in machine language. In practice, however, this is not realistic, even when using a more condensed script thanks to hexadecimal notation (numeration in base 16) for the instructions. It is therefore preferable to use an assembly language. This allows code to be represented by symbolic names, adapted to human understanding, which correspond to instructions in machine language.
Content
- Overview of Cortex-M3 Architecture
- The Core of Cortex-M3
- The Proper Use of Assembly Directives
- Operands of Instructions
- Instruction Set
- Algorithmic and Data Structures
- Internal Modularity
- Managing Exceptions
- From Listing to Executable: External Modularity
