Zilog ZUSBOPTS - Manual (Page 224)

ANSI Standard Compliance UM017105-0511
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Zilog Developer Studio II – ZNEO™
User Manual
By contrast, in the hosted environment, the closest allowed form for main is:
int main (void);
Double Treated as Float
The ZNEO C-Compiler does not support a double-precision floating-point type. The type
double is accepted, but is treated as if it were float .
Library Files Not Required for Freestanding Implementation
As noted in Freestanding Implementation on page 194, only four of the standard library
header files are required by the standard to be supported in a freestanding compiler such as
the ZNEO C-Compiler. However, the compiler does support many of the other standard
library headers as well. The supported headers are listed here. The support offered in the
Zilog libraries is fully compliant with the Standard except as noted here:
•
< assert.h >
•
< ctype.h >
•
< errno.h >
•
< math.h >

The Zilog implementation of the math.h library is not fully ANSI-compliant in the
general limitations of the handling of floating-point numbers: namely, Zilog does not
fully support floating-point NANs, INFINITYs, and related special values. These spe-
cial values are part of the full ANSI/IEEE 754-1985 floating-point standard that is ref-
erenced in the ANSI C Standard.
•
< stddef.h >
•
< stdio.h >
Zilog supports only the portions of stdio.h that make sense in the embedded envi-
ronment. Specifically, Zilog defines the ANSI required functions that do not depend
on a file system. For example,
printf and sprintf are supplied but not fprintf .
•
< stdlib.h >
The stdlib.h header is ANSI-compliant in the Zilog library except that the follow-
ing functions – which are of limited or no use in an embedded environment – are not
supplied:
strtoul()
_Exit()
atexit()