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10
10-2
i960 Processor Compiler User's Guide
•
Set the arithmetic controls (AC) register to
functions to execute correctly, the rounding mode bits of the AC must
be set to round-to-nearest, the floating-point normalizing bit must be
set, and the following faults must be masked:
integer overflow
floating-point overflow
floating-point underflow
floating-point inexact
•
Since the i960 C-series and J-series processors' AC register does not
allow setting of floating-point bits, use
and
_setac
_getac
work correctly for all i960 architectures. Startup routines for KA, KB,
SA, and SB processors can also use the
alternative.
When writing code to initialize the C runtime environment, you must
address the following issues:
•
The startup code provides the bias value for position-independent data
sections. If the program contains position-independent data (PID),
startup code must initialize register
register is the data address bias register. The compiler generates
g12
references to statically allocated variables relative to
contents of
must be divisible by 16 (i.e., the address must be on a
g12
quad-word boundary). After initialization,
read-only; user code should not modify it.
•
If the gcc960 command line specifies
contains the Generate option with the PID argument (
compiler does not use
does use
to offset static variables, as explained above.
g12
If the target environment includes the MON960 monitor, startup must
provide a global entry point called
entry point to the new program. Startup code must call
perform all initializations specific to the processor and to the board.
0x3B001000
_setac
routines are independent of architecture and
modac
to the data-address bias. The
g12
g12
or the ic960 command line
mpid
as a general purpose register. However, it
g12
, used by debug monitors as the
start
. For library
in the setup. The
instruction as an
. The
g12
must be considered
), the
-G pd
to
__LL_init
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