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+@c
+@c  COPYRIGHT (c) 1988-2006.
+@c  On-Line Applications Research Corporation (OAR).
+@c  All rights reserved.
+@c
+@c  $Id$
+@c
+
+@ifinfo
+@end ifinfo
+@chapter Blackfin Specific Information
+
+This chapter discusses the Blackfin architecture dependencies
+in this port of RTEMS.  
+
+@subheading Architecture Documents
+
+For information on the Blackfin architecture,
+refer to the following documents available from
+Analog Devices. 
+
+TBD
+
+@c @itemize @bullet
+@c @item @cite{"ADSP-BF533 Blackfin Processor Hardware Reference."
+@c @file{http://www.analog.com/UploadedFiles/Associated_Docs/892485982bf533_hwr.pdf} 
+@c 
+@c @end itemize
+
+
+@section CPU Model Dependent Features
+
+
+CPUs of the Blackfin 53X only differ in the perifericals
+and thus in the device drivers. This port does not yet
+support the 56X dual core variants.
+
+@subsection CPU Model Name
+
+The macro @code{CPU_MODEL_NAME} is a string which designates
+the architectural level of this CPU model.  The following is
+a list of the settings for this string based upon @code{gcc}
+CPU model predefines:
+
+@example
+"BF533"
+@end example
+
+@subsection Count Leading Zeroes Instruction
+
+The Blackfin CPU has the BITTST instruction
+which could be used to speed up the find first bit
+operation.  The use of this instruction should significantly speed up
+the scheduling associated with a thread blocking.
+
+@subsection Floating Point Unit
+
+The macro BF_HAS_FPU is set to 0 to indicate that
+this CPU model has no hardware floating point unit.
+Blackfin CPUs don't have floating point so 
+
+@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:
+
+@itemize @bullet
+@item register preservation and usage
+@item parameter passing
+@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.
+
+This section is heavily based on content taken from the
+Blackfin uCLinux documentation wiki which is edited
+by Analog Devices and Arcturus Networks.
+@file{http://docs.blackfin.uclinux.org/}
+
+@subsection Processor Background
+
+
+The Blackfin architecture supports a simple call and return mechanism.
+A subroutine is invoked via the call (@code{call}) instruction.
+This instruction saves the return address in the @code{RETS} register
+and transfers the execution to the given address.
+
+It is the called funcions responsability to use the link instruction to
+reserve space on the stack for the local variables.
+Returning from a subroutine is done by using the RTS (@code{RTS})
+instruction which loads the PC with the adress stored in RETS.
+
+It is is important to note that the @code{call} instruction does not
+automatically save or restore any registers.  It is the
+responsibility of the high-level language compiler to define the
+register preservation and usage convention.
+
+@subsection Register Usage
+
+A called function may clobber all registers, except RETS, R4-R7, P3-P5, FP and SP. 
+It may also modify the first 12 bytes in the caller’s stack frame which is used as
+an argument area for the first three arguments (which are passed in R0...R3 but may
+be placed on the stack by the called function).
+
+@subsection Parameter Passing
+
+RTEMS assumes that the Blackfin GCC calling convention is followed.
+The first three parameters are stored in registers R0, R1, and R2.
+All other parameters are put pushed on the stack.
+The result is returned through register R0.
+
+@subsection User-Provided Routines
+
+All user-provided routines invoked by RTEMS, such as
+user extensions, device drivers, and MPCI routines, must also
+adhere to these calling conventions.
+
+@section Memory Model
+
+The Blackfin family architecutre support a single unified 4
+G byte address space using 32-bit addresses. It maps all
+resources like internal and external memory and IO registers
+into separate sections of this common address space.
+
+The Blackfin architcture supporst some form of memory
+protection via its Memory Management Unit. Since the
+Blackfin port runs in supervisior mode this memory
+protection mechanisms are not used.
+
+@section Interrupt Processing
+
+Discussed in this chapter are the Blackfin's
+interrupt response and control mechanisms as they pertain to
+RTEMS. The Blackfin architecture support 16 kinds of
+interrupts broken down into Core and general-purpose
+interrupts.
+
+@subsection Vectoring of an Interrupt Handler
+
+RTEMS maps levels 0 -15 directly to Blackfins event
+vectors EVT0 - EVT15. Since EVT0 - EVT6 are core
+events and it is suggested to use EVT15 and EVT15 for
+Software interrupts, 7 Interrupts (EVT7-EVT13) are left
+for periferical use.
+
+When installing an RTEMS interrupt handler RTEMS installs
+a generic Interrupt Handler which saves some context and
+enables nested interrupt servicing and then vectors
+to the users interrupt handler.
+
+@subsection Disabling of Interrupts by RTEMS
+
+During the execution of directive calls, critical
+sections of code may be executed.  When these sections are
+encountered, RTEMS disables interrupts to level four (4) before
+the execution of this section and restores them to the previous
+level upon completion of the section. RTEMS uses the instructions
+CLI and STI to enable and disable Interrupts. Emulation,
+Reset, NMI and Exception Interrupts are never disabled.
+
+@subsection Interrupt Stack
+
+The Blackfin Architecuter works with two different kind of stacks,
+User and Supervisor Stack. Since RTEMS and its Application run
+in supervisor mode, all interrupts will use the interrupted
+tasks stack for execution.
+
+@section Default Fatal Error Processing
+
+the @code{rtems_fatal_error_occurred} directive when there is
+no user handler configured or the user handler returns control to
+RTEMS.  The default fatal error handler performs the
+following actions:
+
+@itemize @bullet
+@item disables processor interrupts,
+@item places the error code in @b{r0}, and
+@item executes an infinite loop (@code{while(0);} to
+simulate a halt processor instruction.
+@end itemize
+
+@section Board Support Packages
+
+
+@subsection System Reset
+
+TBD
+
+@subsection Processor Initialization
+
+TBD
+
+