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/*  cpu_asm.s

 *

 *  This file contains all assembly code for the Intel i386 implementation

 *  of RTEMS.

 *

 *  COPYRIGHT (c) 1989-1999.

 *  On-Line Applications Research Corporation (OAR).

 *

 *  The license and distribution terms for this file may be

 *  found in the file LICENSE in this distribution or at

 *  http://www.OARcorp.com/rtems/license.html.

 *

 *  $Id: cpu_asm.S,v 1.2 2001-09-27 11:59:26 chris Exp $

 */

#include 

/*

 * Format of i386 Register structure

 */

.set REG_EFLAGS,  0

.set REG_ESP,     REG_EFLAGS + 4

.set REG_EBP,     REG_ESP + 4

.set REG_EBX,     REG_EBP + 4

.set REG_ESI,     REG_EBX + 4

.set REG_EDI,     REG_ESI + 4

.set SIZE_REGS,   REG_EDI + 4

        BEGIN_CODE

/*

 *  void _CPU_Context_switch( run_context, heir_context )

 *

 *  This routine performs a normal non-FP context.

 */

        .p2align  1

        PUBLIC (_CPU_Context_switch)

.set RUNCONTEXT_ARG,   4                   # save context argument

.set HEIRCONTEXT_ARG,  8                   # restore context argument

SYM (_CPU_Context_switch):

        movl      RUNCONTEXT_ARG(esp),eax  # eax = running threads context

        pushf                              # push eflags

        popl      REG_EFLAGS(eax)          # save eflags

        movl      esp,REG_ESP(eax)         # save stack pointer

        movl      ebp,REG_EBP(eax)         # save base pointer

        movl      ebx,REG_EBX(eax)         # save ebx

        movl      esi,REG_ESI(eax)         # save source register

        movl      edi,REG_EDI(eax)         # save destination register

        movl      HEIRCONTEXT_ARG(esp),eax # eax = heir threads context

restore:

        pushl     REG_EFLAGS(eax)          # push eflags

        popf                               # restore eflags

        movl      REG_ESP(eax),esp         # restore stack pointer

        movl      REG_EBP(eax),ebp         # restore base pointer

        movl      REG_EBX(eax),ebx         # restore ebx

        movl      REG_ESI(eax),esi         # restore source register

        movl      REG_EDI(eax),edi         # restore destination register

        ret

/*

 *  NOTE: May be unnecessary to reload some registers.

 */

/*

 *  void _CPU_Context_restore( new_context )

 *

 *  This routine performs a normal non-FP context.

 */

        PUBLIC (_CPU_Context_restore)

.set NEWCONTEXT_ARG,   4                   # context to restore argument

SYM (_CPU_Context_restore):

        movl      NEWCONTEXT_ARG(esp),eax  # eax = running threads context

        jmp       restore

/*PAGE

 *  void _CPU_Context_save_fp_context( &fp_context_ptr )

 *  void _CPU_Context_restore_fp_context( &fp_context_ptr )

 *

 *  This section is used to context switch an i80287, i80387,

 *  the built-in coprocessor or the i80486 or compatible.

 */

.set FPCONTEXT_ARG,   4                    # FP context argument

        .p2align  1

        PUBLIC (_CPU_Context_save_fp)

SYM (_CPU_Context_save_fp):

        movl      FPCONTEXT_ARG(esp),eax   # eax = &ptr to FP context area

        movl      (eax),eax                # eax = FP context area

        fsave     (eax)                    # save FP context

        ret

        .p2align  1

        PUBLIC (_CPU_Context_restore_fp)

SYM (_CPU_Context_restore_fp):

        movl      FPCONTEXT_ARG(esp),eax   # eax = &ptr to FP context area

        movl      (eax),eax                # eax = FP context area

        frstor    (eax)                    # restore FP context

        ret

        PUBLIC (_Exception_Handler)

SYM (_Exception_Handler):

        pusha                              # Push general purpose registers

        pushl   esp                        # Push exception frame address

        movl    _currentExcHandler, eax    # Call function storead in _currentExcHandler

        call    * eax

        addl    $4, esp

        popa                               # restore general purpose registers

        addl    $8, esp                    # skill vector number and faultCode

        iret

#define DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY(_vector) \

        .p2align 4                         ; \

        PUBLIC (rtems_exception_prologue_ ## _vector ) ; \

SYM (rtems_exception_prologue_ ## _vector ):             \

        pushl   $ _vector       ; \

        jmp   SYM (_Exception_Handler) ;

#define DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY(_vector) \

        .p2align 4                         ; \

        PUBLIC (rtems_exception_prologue_ ## _vector ) ; \

SYM (rtems_exception_prologue_ ## _vector ):             \

        pushl   $ 0             ; \

        pushl   $ _vector       ; \

        jmp   SYM (_Exception_Handler) ;

/*

 * Divide Error

 */

DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (0)

/*

 * Debug Exception

 */

DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (1)

/*

 * NMI

 */

DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (2)

/*

 * Breakpoint

 */

DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (3)

/*

 * Overflow

 */

DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (4)

/*

 * Bound Range Exceeded

 */

DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (5)

/*

 * Invalid Opcode

 */

DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (6)

/*

 * No Math Coproc

 */

DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (7)

/*

 * Double Fault

 */

DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (8)

/*

 * Coprocessor segment overrun

 */

DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (9)

/*

 * Invalid TSS

 */

DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (10)

/*

 * Segment Not Present

 */

DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (11)

/*

 * Stack segment Fault

 */

DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (12)

/*

 * General Protection Fault

 */

DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (13)

/*

 * Page Fault

 */

DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (14)

/*

 * Floating point error (NB 15 is reserved it is therefor skipped)

 */

DISTINCT_EXCEPTION_WITHOUT_FAULTCODE_ENTRY (16)

/*

 * Aligment Check

 */

DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (17)

/*

 * Machine Check

 */

DISTINCT_EXCEPTION_WITH_FAULTCODE_ENTRY (18)

/*

 *  void *i386_Logical_to_physical(

 *     rtems_unsigned16  segment,

 *     void             *address

 *  );

 *

 *  Returns thirty-two bit physical address for segment:address.

 */

.set SEGMENT_ARG, 4

.set ADDRESS_ARG, 8

             PUBLIC (i386_Logical_to_physical)

SYM (i386_Logical_to_physical):

        xorl    eax,eax                # clear eax

        movzwl  SEGMENT_ARG(esp),ecx   # ecx = segment value

        movl    $ SYM (_Global_descriptor_table),edx

                                       # edx = address of our GDT

        addl    ecx,edx                # edx = address of desired entry

        movb    7(edx),ah              # ah = base 31:24

        movb    4(edx),al              # al = base 23:16

        shll    $16,eax                # move ax into correct bits

        movw    2(edx),ax              # ax = base 0:15

        movl    ADDRESS_ARG(esp),ecx   # ecx = address to convert

        addl    eax,ecx                # ecx = physical address equivalent

        movl    ecx,eax                # eax = ecx

        ret

/*

 *  void *i386_Physical_to_logical(

 *     rtems_unsigned16  segment,

 *     void             *address

 *  );

 *

 *  Returns thirty-two bit physical address for segment:address.

 */

/*

 *.set SEGMENT_ARG, 4

 *.set ADDRESS_ARG, 8   -- use sets from above

 */

       PUBLIC (i386_Physical_to_logical)

SYM (i386_Physical_to_logical):

        xorl    eax,eax                # clear eax

        movzwl  SEGMENT_ARG(esp),ecx   # ecx = segment value

        movl    $ SYM (_Global_descriptor_table),edx

                                       # edx = address of our GDT

        addl    ecx,edx                # edx = address of desired entry

        movb    7(edx),ah              # ah = base 31:24

        movb    4(edx),al              # al = base 23:16

        shll    $16,eax                # move ax into correct bits

        movw    2(edx),ax              # ax = base 0:15

        movl    ADDRESS_ARG(esp),ecx   # ecx = address to convert

        subl    eax,ecx                # ecx = logical address equivalent

        movl    ecx,eax                # eax = ecx

        ret

END_CODE

END