2. Concepts |
11 |
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2.2Loading and Execution of Programs
After a program has been compiled and linked, it can be executed. While compilation and linking is basically identical for embedded systems and general purpose computers, there are some differences regarding the execution of programs. Table 2.1 lists the steps performed during program execution and shows the differences between general purpose computers and embedded systems:
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General Purpose Computer |
Embedded System |
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1 |
The TEXT section of the program |
The TEXT section is already |
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is loaded into the program memory |
existing in the program memory |
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(part of the computer’s RAM). |
(EEPROM) of the embedded |
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system. |
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2 |
Depending on the object format |
The addresses are computed by the |
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generated by the linker, the |
linker. |
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addresses of the TEXT section may |
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need to be relocated. If the compiler |
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produced position independent |
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code (PIC), this step is omitted. |
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3 |
The DATA section of the program |
The DATA section is already in the |
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is loaded into program memory |
EEPROM of the embedded system. |
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(part of the computer’s RAM). |
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4 |
Depending of the object format |
The DATA section is copied as a |
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generated by the linker, the |
whole to its final address in RAM. |
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addresses of the TEXT section may |
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need to be relocated. |
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TABLE 2.1 Execution of a program
Obviously, the execution of a program in an embedded system is much easier than in a general purpose computer.