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doc: Clarify ABI in SPARC CPU supplement

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Sebastian Huber
2014-09-12 16:13:55 +02:00
parent f9eca790ac
commit 1434dbd6eb
1 changed files with 16 additions and 11 deletions
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doc/cpu_supplement/sparc.t
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@@ -214,11 +214,9 @@ initialization time.
@section Calling Conventions
Each high-level language compiler generates
subroutine entry and exit code based upon a set of rules known
as the compiler's calling convention. These rules address the
following issues:
Each high-level language compiler generates subroutine entry and exit code
based upon a set of rules known as the application binary interface (ABI)
calling convention. These rules address the following issues:
@itemize @bullet
@item register preservation and usage
@@ -228,12 +226,13 @@ following issues:
@item call and return mechanism
@end itemize
A compiler's calling convention is of importance when
interfacing to subroutines written in another language either
assembly or high-level. Even when the high-level language and
target processor are the same, different compilers may use
different calling conventions. As a result, calling conventions
are both processor and compiler dependent.
An ABI calling convention is of importance when interfacing to subroutines
written in another language either assembly or high-level. It determines also
the set of registers to be saved or restored during a context switch and
interrupt processing.
The ABI relevant for RTEMS on SPARC is defined by SYSTEM V APPLICATION BINARY
INTERFACE, SPARC Processor Supplement, Third Edition.
@subsection Programming Model
@@ -567,6 +566,12 @@ call and return mechanism does not automatically save and
restore any registers. This is accomplished via the save and
restore instructions which manage the set of registers windows.
In case a floating-point unit is supported, then floating-point return values
appear in the floating-point registers. Single-precision values occupy %f0;
double-precision values occupy %f0 and %f1. Otherwise, these are scratch
registers. Due to this the hardware and software floating-point ABIs are
incompatible.
@subsection Calling Mechanism
All RTEMS directives are invoked using the regular