Fujitsu FR60 Hardware Manual page 58

CHAPTER 2 HANDLING THE DEVICE
■ Specification of the -K lib Option when Character String Operation Functions are Used
When the -K lib option is specified, the compiler expands several character string operation functions
inline. Because the compiler selects the optimum processing method at this time, processing may change
for each halfword or word.
If the processing changes, processing for the little-endian area will not be executed correctly.
Do not specify the -K lib option when executing processing that uses character string operation functions
for the little-endian area. In addition, do not specify the -O 4 or -K speed option that includes the -K lib
option.
■ Use of the Double Type and Long Double Type
In double type access, the high-order word is accessed. In long double type access, the low-order word is
accessed.
For this reason, the correct result will not be obtained when double type and long double type variables
mapped in the little-endian area are accessed.
Variables of the same type allocated in the little-endian area can be assigned among the variables.
However, optimization can replace the assignment of these variables with an assignment of literals.
Do not map double type and long double type variables in the little-endian area.
Incorrect processing example:
Transferring double type data
The result of executing the above code is shown below. An error occurs when the double type data is
transferred.
■ Mapping of the Stack to the Little-endian Area
Operation will be unpredictable if part or all of the stack is mapped to the little-endian area.
40
double big = 1.0;
extern int little;
little = big;
(Big-endian area)
3f f0 00 00 00 00 00 00
(Correct result)
/* Big-endian area */
/* Little-endian area */
/* Transfer double type data */
(Little-endian area)
00 00 f0 3f 00 00 00 00
00 00 00 00 00 00 f0 3f