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Dr. Andrew Greensted
Last modified: 18th November 2009

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Code Segments

A few bits of information on code segments and linking.

Note: This HowTo uses Xilinx EDK version 9.1i

Code Segments

Below is a list of some of the code segments that GCC can produce with descriptions of their purpose.

.textProgram code
.dataInitialised global data
.sdataSmall .data
.bssUninitialised global data (Block Starting Symbol)
.sbssSmall .bss
.rodataConstants (Read only data)
.sdata2Small read only data

Below is an example taken from the Xilinx application note xapp642. It shows how different variables relate to code segments.

File: example.c
#include <stdio.h>
int array_data[10] = {0,1,2,3,4,5,6,7,8,9};
⇐ .data
const int array_const[10] = {9,8,7,6,5,4,3,2,1,0};
⇐ .rodata
int main(void)
   int i;
⇐ .bss
   i = i + 10;
⇐ .text
   printf("%d\n", array_data[0]);
⇐ .text
   array_data[0] = array_const[0];
⇐ .text
⇐ .text
   return 0;

Further Reading

Suggestions for further reading.

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