fpparchlib.c

vxworks源码源码解读是学习vxworks的最佳途径

/* fppArchLib.c - architecture-dependent floating-point coprocessor support */

/* Copyright 1984-1997 Wind River Systems, Inc. */

/*
modification history
--------------------
01e,27feb97,jpd  added ARM-specific documentation.
01d,25nov95,jdi  removed 29k stuff.
01c,31jan95,rhp update for MIPS R4000, AM29K, i386/i486.
            jdi changed 80960 to i960.
01b,20jan93,jdi documentation cleanup.
01a,23sep92,jdi	written, based on fppALib.s and fppArchLib.c for
		mc68k, sparc, i960, mips.
*/

/*
DESCRIPTION
This library contains architecture-dependent routines to support the 
floating-point coprocessor.  The routines fppSave() and fppRestore() save
and restore all the task floating-point context information.  The routine
fppProbe() checks for the presence of the floating-point coprocessor.  The
routines fppTaskRegsSet() and fppTaskRegsGet() inspect and set coprocessor
registers on a per-task basis.

With the exception of fppProbe(), the higher-level facilities in dbgLib
and usrLib should be used instead of these routines.  For information about
architecture-independent access mechanisms, see the manual entry for fppLib.

INITIALIZATION
To activate floating-point support, fppInit() must be called before any
tasks using the coprocessor are spawned.  This is done by the root task,
usrRoot(), in usrConfig.c.  See the manual entry for fppLib.

NOTE I386/I486
On this architecture, VxWorks disables the six FPU exceptions that can
send an IRQ to the CPU.

NOTE ARM
This architecture does not currently support floating-point coprocessors.


INCLUDE FILES: fppLib.h

SEE ALSO: fppLib, intConnect(),
.nf
.IR "Motorola MC68881/882 Floating-Point Coprocessor User's Manual" ,
.IR "SPARC Architecture Manual" ,
.IR "Intel 80960SA/SB Reference Manual" ,
.IR "Intel 80960KB Programmer's Reference Manual" ,
.IR "Intel 387 DX User's Manual" ,
.fi
Gerry Kane and Joe Heinrich:
.I "MIPS RISC Architecture Manual"
*/


/*******************************************************************************
*
* fppSave - save the floating-point coprocessor context
*
* This routine saves the floating-point coprocessor context.
* The context saved is:
*
* \&MC680x0:
*	- registers `fpcr', `fpsr', and `fpiar'
*	- registers `f0' - `f7'
*	- internal state frame (if NULL, the other registers are not saved.)
*
* \&SPARC:
*	- registers `fsr' and `fpq'
*	- registers `f0' - `f31'
*
* \&i960:
*	- registers `fp0' - `fp3'
*
* \&MIPS:
*	- register `fpcsr'
*	- registers `fp0' - `fp31'
*
* \&i386/i486:
*       - control word, status word, tag word, IP offset, CS selector,
*         data operand offset, and operand selector (4 bytes each)
*       - registers `st0' - `st7' (8 bytes each)
*
* \&ARM:
*       - currently, on this architecture, this routine does nothing.
*
* RETURNS: N/A
*
* SEE ALSO: fppRestore()
*/

void fppSave
    (
    FP_CONTEXT *  pFpContext	/* where to save context */
    )

    {
    ...
    }



/*******************************************************************************
*
* fppRestore - restore the floating-point coprocessor context
*
* This routine restores the floating-point coprocessor context.
* The context restored is:
*
* \&MC680x0:
*	- registers `fpcr', `fpsr', and `fpiar'
*	- registers `f0' - `f7'
*	- internal state frame (if NULL, the other registers are not saved.)
*
* \&SPARC:
*	- registers `fsr' and `fpq'
*	- registers `f0' - `f31'
*
* \&i960:
*	- registers `fp0' - `fp3'
*
* \&MIPS:
*	- register `fpcsr'
*	- registers `fp0' - `fp31'
*
* \&i386/i486:
*       - control word, status word, tag word, IP offset, CS selector,
*         data operand offset, and operand selector
*       - registers `st0' - `st7'
*
* \&ARM:
*       - currently, on this architecture, this routine does nothing.
*
* RETURNS: N/A
*
* SEE ALSO: fppSave()
*/

void fppRestore
    (
    FP_CONTEXT *  pFpContext	/* where to restore context from */
    )

    {
    ...
    }

/*******************************************************************************
*
* fppProbe - probe for the presence of a floating-point coprocessor
*
* This routine determines whether there is a
* floating-point coprocessor in the system.
*
* The implementation of this routine is architecture-dependent:
*
* .IP "MC680x0, SPARC, i386/i486:"
* This routine sets the illegal coprocessor opcode trap vector and executes
* a coprocessor instruction.  If the instruction causes an exception,
* fppProbe() returns ERROR.  Note that this routine saves and restores
* the illegal coprocessor opcode trap vector that was there prior to this
* call.
*
* The probe is only performed the first time this routine is called.
* The result is stored in a static and returned on subsequent
* calls without actually probing.
*
* .IP i960:
* This routine merely indicates whether VxWorks was compiled with
* the flag `-DCPU=I960KB'.
*
* .IP MIPS:
* This routine simply reads the R-Series status register and reports
* the bit that indicates whether coprocessor 1 is usable.  This bit
* must be correctly initialized in the BSP.
*
* .IP ARM:
* This routine currently returns ERROR to indicate no floating-point coprocessor
* support.
* 
* INTERNAL
* The STAR board will always have an on-board floating-point unit.
* What about others?
*
* RETURNS:
* OK, or ERROR if there is no floating-point coprocessor.
*/

STATUS fppProbe (void)

    {
    ...
    }

/*******************************************************************************
*
* fppTaskRegsGet - get the floating-point registers from a task TCB
*
* This routine copies a task's floating-point registers and/or status
* registers to the locations whose pointers are passed as
* parameters.  The floating-point registers are copied into
* an array containing all the registers.
*
* NOTE
* This routine only works well if <task> is not the calling task.
* If a task tries to discover its own registers, the values will be stale
* (that is, left over from the last task switch).
*
* RETURNS: OK, or ERROR if there is no floating-point
* support or there is an invalid state.
*
* SEE ALSO: fppTaskRegsSet()
*/

STATUS fppTaskRegsGet
    (
    int		 task,       	/* task to get info about */
    FPREG_SET *  pFpRegSet	/* ptr to floating-point register set */
    )

    {
    ...
    }

/*******************************************************************************
*
* fppTaskRegsSet - set the floating-point registers of a task
*
* This routine loads the specified values into the TCB of a specified task.
* The register values are copied from the array at <pFpRegSet>.
*
* RETURNS: OK, or ERROR if there is no floating-point
* support or there is an invalid state.
*
* SEE ALSO: fppTaskRegsGet()
*/

STATUS fppTaskRegsSet
    (
    int		 task,          /* task to set registers for */
    FPREG_SET *	 pFpRegSet	/* ptr to floating-point register set */
    )

    {
    ...
    }