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CARM User's Guide
CARM Introduction Compiling Programs Language Extensions Preprocessor Advanced Programming Customization Files
Startup Code Basic I/O Memory Allocation Interfacing C to Assembler Function Parameters Function Return Values Using the SRC Directive Register Usage Example Routines ARM Code Example Thumb Code Example Data Storage Formats Byte Order Byte Alignment Integer Scalars 1-Byte Scalars 2-Byte Scalars 4-Byte Scalars 8-Byte Scalars float Scalars float Format float Errors double Scalars double Format double Errors Pointers Bit Fields Absolute Memory Access The __at Keyword Linker Location Controls Error Messages Library Reference Appendixfloat Errors
The CARM Compiler detects floating-point errors and reports them by setting the float value to one of several special binary values. Your software must appropriately respond to floating-point error conditions.
The floating-point error values are defined as a part of the IEEE standard and are used whenever an error occurs during normal processing of floating-point operations. Your code should check for possible arithmetic errors at the end of each floating-point operation.
| Name | Value | Meaning |
|---|---|---|
| NaN | 0xFFFFFFF | Not a Number |
| +INF | 0x7F80000 | Positive Infinity (positive overflow) |
| -INF | 0xFF80000 | Negative Infinity (negative overflow) |
| ZERO | 0x0000000 | Zero Value |
The CARM library function _chkfloat_ allows you to quickly check the floating-point status of float numbers.
Note
- Not a number (NaN) is represented by setting the exponent to the highest positive value and the mantissa to a non-zero value. The value of the sign bit is ignored.
- Infinity (+INF or -INF) is represented by setting the exponent to the highest value and the mantissa to zero. The sign bit signifies positive or negative infinity.
- Zero is represented by a zero sign, mantissa, and exponent.
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