Epson S5U1C17001C, Manual

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S5U1C17001C ManUal
EPSOn
6-13
(C COMPilEr PaCkagE fOr S1C17 faMily) (Ver. 1.5.0)
6 C COMPilEr
6
Compiler
return address
This is the return address to the caller function.
register save area
If any registers from
%r4
to
%r7
are used by the caller function, they are saved to this area.
If none of the registers from
%r4
to
%r7
is used by the caller function, this area is not allocated.
local variable area
If there are any local variables defined in the called function that cannot be stored in registers, an area is
allocated in the stack frame. Then they are saved sequentially beginning with the last-declared variable at
boundary addresses according to the data types.
Example:
{
char cData;
short sData;
long lData;
:
}
Low memory
+0 +1 +2 +3
cData Local start Unused
lData +4
+0
sData
Figure 6.4.5.2 Example of local variables saved to stack
Depending on the source codes, the variables may not be located in the order of declarations due to
optimization.
This area is not allocated if there is no local variable that needs to be saved in the stack.
6.4.6 grammar of C Source
Refer to Section 4.2, "Grammar of C Source", for data type, library functions and header files, in-line assemble, and
prototype declarations (declaring interrupt handler functions).
6.4.7 Compiler implementation Definition
C language specifications permit implementation-defined adjustment of the method of configuring member variables
of a structure or union.
The C compiler in this package is adjusted to yield even-number bytes for the size of a structure or union as an
implementation definition feature.