hal_misc.c

eCos1.31版

//===========================================================================
//
//      hal_misc.c
//
//      HAL miscellaneous functions
//
//===========================================================================
//####COPYRIGHTBEGIN####
//                                                                          
// -------------------------------------------                              
// The contents of this file are subject to the Red Hat eCos Public License 
// Version 1.1 (the "License"); you may not use this file except in         
// compliance with the License.  You may obtain a copy of the License at    
// http://www.redhat.com/                                                   
//                                                                          
// Software distributed under the License is distributed on an "AS IS"      
// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See the 
// License for the specific language governing rights and limitations under 
// the License.                                                             
//                                                                          
// The Original Code is eCos - Embedded Configurable Operating System,      
// released September 30, 1998.                                             
//                                                                          
// The Initial Developer of the Original Code is Red Hat.                   
// Portions created by Red Hat are                                          
// Copyright (C) 1998, 1999, 2000 Red Hat, Inc.                             
// All Rights Reserved.                                                     
// -------------------------------------------                              
//                                                                          
//####COPYRIGHTEND####
//===========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):    nickg
// Contributors: proven, pjo
// Date:        1999-02-20
// Purpose:     HAL miscellaneous functions
// Description: This file contains miscellaneous functions provided by the
//              HAL.
//
//####DESCRIPTIONEND####
//
//===========================================================================

#include <pkgconf/hal.h>

#include <cyg/infra/cyg_type.h>

#include <cyg/hal/hal_arch.h>

void hal_zero_bss(void)
{	extern char _end ;
	extern char __bss_start ;

	asm(
		"movl %0, %%ecx;"           /* Get the address of _end */
		"movl %1, %%edi;"           /* Address of __bss_start */
		"subl %%edi, %%ecx;"        /* Number of bytes in %ecx */
		"addl $3, %%ecx;"           /* Round up to the next 32-bits */
		"shr $2, %%ecx;"            /* Divide by 4: we'll fill 32-bit words. */
		"xorl %%eax, %%eax;"        /* Store zeros. */
		"rep
		stosl"                      /* Fill the region. */
	:	/* No outputs. */
	:	"g" (&_end), "g" (&__bss_start)
	:	"ecx", "edi", "eax"
	);
}

//---------------------------------------------------------------------------

#ifdef CYGSEM_HAL_STOP_CONSTRUCTORS_ON_FLAG
cyg_bool cyg_hal_stop_constructors;
#endif

typedef void (*pfunc) (void);
extern pfunc __CTOR_LIST__[];
extern pfunc __CTOR_END__[];

void
cyg_hal_invoke_constructors (void)
{
#ifdef CYGSEM_HAL_STOP_CONSTRUCTORS_ON_FLAG
    static pfunc *p = &__CTOR_END__[-1];
    
    cyg_hal_stop_constructors = 0;
    for (; p >= __CTOR_LIST__; p--) {
        (*p) ();
        if (cyg_hal_stop_constructors) {
            p--;
            break;
        }
    }
#else
    pfunc *p;

    for (p = &__CTOR_END__[-1]; p >= __CTOR_LIST__; p--)
        (*p) ();
#endif
}

//---------------------------------------------------------------------------
// Determine the index of the ls bit of the supplied mask.

cyg_uint32
hal_lsbit_index(cyg_uint32 mask)
{
    cyg_uint32 n = mask;

    static const signed char tab[64] =
    { -1, 0, 1, 12, 2, 6, 0, 13, 3, 0, 7, 0, 0, 0, 0, 14, 10,
      4, 0, 0, 8, 0, 0, 25, 0, 0, 0, 0, 0, 21, 27 , 15, 31, 11,
      5, 0, 0, 0, 0, 0, 9, 0, 0, 24, 0, 0 , 20, 26, 30, 0, 0, 0,
      0, 23, 0, 19, 29, 0, 22, 18, 28, 17, 16, 0
    };

    n &= ~(n-1UL);
    n = (n<<16)-n;
    n = (n<<6)+n;
    n = (n<<4)+n;

    return tab[n>>26];
}

//---------------------------------------------------------------------------
// Determine the index of the ms bit of the supplied mask.

cyg_uint32
hal_msbit_index(cyg_uint32 mask)
{
    cyg_uint32 x = mask;    
    cyg_uint32 w;

    // Phase 1: make word with all ones from that one to the right.
    x |= x >> 16;
    x |= x >> 8;
    x |= x >> 4;
    x |= x >> 2;
    x |= x >> 1;

    // Phase 2: calculate number of "1" bits in the word.
    w = (x & 0x55555555) + ((x >> 1) & 0x55555555);
    w = (w & 0x33333333) + ((w >> 2) & 0x33333333);
    w = w + (w >> 4);
    w = (w & 0x000F000F) + ((w >> 8) & 0x000F000F);
    return (cyg_uint32)((w + (w >> 16)) & 0xFF);

}

//---------------------------------------------------------------------------
// First level C exception handler.

#if 0 // FIXME - exceptions aren't supported

void
cyg_hal_exception_handler(HAL_SavedRegisters *regs)
{
    // We should decode the vector and pass a more appropriate
    // value as the second argument. For now we simply pass a
    // pointer to the saved registers. We should also divert
    // breakpoint and other debug vectors into the debug stubs.
    
#if defined(CYGFUN_HAL_COMMON_KERNEL_SUPPORT) && defined(CYGPKG_HAL_EXCEPTIONS)

    cyg_hal_deliver_exception( regs->vector>>8, (CYG_ADDRWORD)regs );

#else
    
    CYG_FAIL("Exception!!!");
    
#endif    
    
    return;
}

#endif
//---------------------------------------------------------------------------
// End of hal_misc.c