Intel i960 - Language Extensions

Language Implementation
7-39
7
index is the index of the system function in the system
procedure table and is available to the linker
through the symbol table entry for the function.
This value must be in the range
0 to 259.
For information on the
calljx and calls instructions and the system
function table, refer to the i960 Processor Assembler User's Guide.
You must associate a single system procedure table index with each
system function before the final link of your program. The linker
generates an error message for any system function that has no index or
multiple conflicting indexes.
You can make this association in either or both of the following ways, if
the defined index is consistent across all definitions:
• Specify
pragma system at both the definition and the calling of the
function. The compiler then generates the appropriate symbol table
information, including the index.
• Use the
.sysproc assembler directive to associate a system function
name with an index.
Since register
g13 is used for the system function index, a system function
cannot return a value larger than four words. Refer to the i960 Processor
Software Utilities User's Guide for more information.
Language Extensions
GNU C provides several language features not found in ANSI standard C.
(The
pedantic option directs gcc960 to print a warning message if any of
these features is used.) To test for the availability of these features in
conditional compilation, check for a predefined macro
__GNUC__, which
is automatically defined under gcc960 (but not under ic960).