ARM Compiler toolchain v4.1 for µVision Using the Compiler

Compiler Coding Practices
5.55 Examining parameters when integer division-by-zero errors occur in C code
If you want to examine parameters and save them for postmortem debugging, you can trap
__aeabi_idiv0. You can intervene in all calls to __aeabi_idiv0 by using the $Super$$ and $Sub$$
mechanism.
To examine parameters when integer division-by-zero occurs:
1. Prefix __aeabi_idiv0() with $Super$$ to identify the original unpatched function
__aeabi_idiv0().
2. Use __aeabi_idiv0() prefixed with $Super$$ to call the original function directly.
3. Prefix __aeabi_idiv0() with $Sub$$ to identify the new function to be called in place of
the original version of __aeabi_idiv0().
4. Use __aeabi_idiv0() prefixed with $Sub$$ to add processing before or after the original
function __aeabi_idiv0().
5.55.1 Example
Example 5-5 illustrates the use of the $Super$$ and $Sub$$ mechanism to intercept __aeabi_div0.
Example 5-5 Intercepting __aeabi_div0 using $Super$$ and $Sub$$
extern void $Super$$__aeabi_idiv0(void);
/* this function is called instead of the original __aeabi_idiv0() */
void $Sub$$__aeabi_idiv0()
{
// insert code to process a divide by zero
...
// call the original __aeabi_idiv0 function
$Super$$__aeabi_idiv0();
}
5.55.2 See also
Concepts
• Integer division-by-zero errors in C code on page 5-67.
Using the Linker:
• Using $Super$$ and $Sub$$ to patch symbol definitions on page 7-28.
Other information
• Run-time ABI for the ARM Architecture,
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0043-/index.html.
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