-nostdlib option!

-nostdlib option!

[ali hagigat]

I have copied part of gcc manual:
------------------------------------
Do not use the standard system startup files or libraries when
linking.  No startup files and only the libraries you specify will be
passed to the linker.  The compiler may generate calls to "memcmp",
"memset", "memcpy" and "memmove".  These entries are usually resolved
by entries in libc.  These entry points should be supplied through
some other mechanism when this option is specified.
------------------------------------
What is some other mechanism? How can i use -nostdlib?

Re: -nostdlib option!

[Drasko DRASKOVIC]

On Mon, Feb 7, 2011 at 12:03 PM, ali hagigat <hagigatali@gmail.com> wrote:
> I have copied part of gcc manual:
> ------------------------------------
> Do not use the standard system startup files or libraries when
> linking.  No startup files and only the libraries you specify will be
> passed to the linker.  The compiler may generate calls to "memcmp",
> "memset", "memcpy" and "memmove".  These entries are usually resolved
> by entries in libc.  These entry points should be supplied through
> some other mechanism when this option is specified.
> ------------------------------------
> What is some other mechanism? How can i use -nostdlib?

You posted the answer to your question already.

BR,
Drasko

RE: -nostdlib option!

[Manuel Coutinho]

Hi

Other mechanism: supply your own memset, memcpy, etc.
If you do this, the linker will know which memset, memcpy, etc to use and
will not complaint about not using libc.

Regards
Manuel Coutinho

-----Original Message-----
From: gcc-help-owner@gcc.gnu.org [mailto:gcc-help-owner@gcc.gnu.org] On
Behalf Of ali hagigat
Sent: 07 February 2011 11:04
To: gcc-help@gcc.gnu.org
Subject: -nostdlib option!

I have copied part of gcc manual:
------------------------------------
Do not use the standard system startup files or libraries when
linking.  No startup files and only the libraries you specify will be
passed to the linker.  The compiler may generate calls to "memcmp",
"memset", "memcpy" and "memmove".  These entries are usually resolved
by entries in libc.  These entry points should be supplied through
some other mechanism when this option is specified.
------------------------------------
What is some other mechanism? How can i use -nostdlib?

Re: -nostdlib option!

[ali hagigat]

Thank you Manuel.
How will be memset, memcpy, etc. Can i copy them from the source code
of gcc? But they are dependent to other functions in other libraries
probably and some headers.
Are those functions available stand alone some where?


On Mon, Feb 7, 2011 at 2:51 PM, Manuel Coutinho
> Hi
>
> Other mechanism: supply your own memset, memcpy, etc.
> If you do this, the linker will know which memset, memcpy, etc to use and
> will not complaint about not using libc.
>
> Regards
> Manuel Coutinho
>

Re: -nostdlib option!

[Kai Ruottu]

7.2.2011 14:44, ali hagigat kirjoitti:

> How will be memset, memcpy, etc. Can i copy them from the source code
> of gcc? But they are dependent to other functions in other libraries
> probably and some headers.

Most probably these functions are standalone and don't
call other functions... Does your program really call
them? What does 'nm' say anout undefined symbols in the
compiled object(s)?

> Are those functions available stand alone some where?

For instance in :
   newlib-1.18.0/newlib/libc/machine/i386
in the current newlib sources.

RE: -nostdlib option!

[Manuel Coutinho]

Yes.

Memset and memcpy are standalone functions. My team (at Edisoft) has a
version for these files.

For memcpy we have the file:

/**
 * @brief check if either of the addresses are aligned
 *
 * Nonzero if either X or Y is not aligned on a "long" boundary.
 */
#define UNALIGNED(X, Y) \
  (((uint32)X & (sizeof (uint32) - 1U)) | ((uint32)Y & (sizeof (uint32) -
1U)))

/**
 * @brief determine how many bytes are copied each iteration of the 4X
unrolled
 * loop
 */
#define BIGBLOCKSIZE    ((uint32)sizeof (sint32) << 2U)

/**
 * @brief determine how many bytes are copied each iteration of the word
copy
 * loop
 */
#define LITTLEBLOCKSIZE ((uint32)sizeof (sint32))

/**
 * @brief Threshhold for punting to the byte copier  */ #define
TOO_SMALL(LEN)  ((LEN) < BIGBLOCKSIZE)


void *memcpy(void *dst0 , const void *src0 , rtems_size len0) {

#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)

    /* get destination address as a byte pointer */
    sint8 *dst = (sint8 *) dst0;

    /* get source address as a byte pointer */
    sint8 *src = (const sint8 *) src0;

    
    /* save the destination address */
    void * save = dst0;

    /* copy the source vector to destination for len0 bytes*/
    while(len0--)
    {
        /* copy the source to the destination */
        *dst++ = *src++;
    }

    /* return the saved destination address */
    return save;

#else

    /* get destination address as a byte pointer */
    sint8 *dst = (sint8 *) dst0;

    /* get source address as a byte pointer */
    const sint8 *src = src0;

    /* alligned destination pointer */
    sint32 *aligned_dst;

    /* aligned source pointer */
    const sint32 *aligned_src;

    /* lenght in integer */
    uint32 len = (uint32) len0;


    /* If the size is small, or either SRC or DST is unaligned,
     * then punt into the byte copy loop.  This should be rare.  */
    if(( ( TOO_SMALL(len) ) == 0U ) &&
       ( ( UNALIGNED((uint32) src0 , (uint32) dst0) ) == FALSE ))
    {
        /* get the destination */
        aligned_dst = (sint32*) dst;

        /* get the source */
        aligned_src = (sint32*) src;

        /* Copy 4X long words at a time if possible.  */
        while(len >= BIGBLOCKSIZE)
        {
            /* copy the first 4 bytes */
            *aligned_dst = *aligned_src;
            aligned_dst++;
            aligned_src++;

            /* copy the second 4 bytes */
            *aligned_dst = *aligned_src;
            aligned_dst++;
            aligned_src++;

            /* copy the third 4 bytes */
            *aligned_dst = *aligned_src;
            aligned_dst++;
            aligned_src++;

            /* copy the fourth 4 bytes */
            *aligned_dst = *aligned_src;
            aligned_dst++;
            aligned_src++;

            /* decrement the number of bytes left to copy */
            len -= BIGBLOCKSIZE;
        }

        /* Copy one long word at a time if possible.  */
        while(len >= LITTLEBLOCKSIZE)
        {
            /* copy 4 bytes */
            *aligned_dst = *aligned_src;
            aligned_dst++;
            aligned_src++;

            /* decrement the number of bytes left to copy */
            len -= LITTLEBLOCKSIZE;
        }

        /* Pick up any residual with a byte copier.  */
        dst = (sint8*) aligned_dst;
        src = (sint8*) aligned_src;
    }

    /* copy residual bytes (maximum of 3) */
    while(len > 0U)
    {
        /* copy each byte */
        *dst = *src;

        /* increment the pointer */
        dst++;
        src++;

        /* decrement number of bytes */
        len--;
    }

    /* return the destination address */
    return dst0;
    
#endif /* not PREFER_SIZE_OVER_SPEED */
}




For the file memset.c we have the file:


/**
 * @brief size of a block
 */
#define LBLOCKSIZE ((uint32) sizeof(uintptr))

/**
 * @brief check if the address is alligned  */ #define UNALIGNED(X)
((uintptr)X & (LBLOCKSIZE - 1))

/**
 * @brief check if the size is too small  */ #define TOO_SMALL(LEN) ((LEN) <
LBLOCKSIZE)


void *memset(void *m , sint32 c , rtems_size n) {

#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)

    /* copy the destination address to another variable */
    sint8 *s = (sint8 *) m;


    /* while there are bytes left to copy */
    while(n != 0)
    {
        /* copy the byte */
        *s = (sint8) c;

        /* increment index on array */
        s++;

        /* decrement number of remaining bytes to copy */
        n--;
    }

    /* return the destination address */
    return m;

#else
    
    /* pointer to address where to write */
    sint8 *s = (sint8 *) m;

    /* iterator */
    uint32 i;

    /* buffer where to place small array */
    uint32 buffer;

    /* pointer to address aligned */
    uintptr *aligned_addr;

    /* To avoid sign extension, copy c to an unsigned variable.  */
    uint32 d = (uint32) c & 0xffU;


    /* check if the size is too small or the destination address in not
aligned */
    if(( TOO_SMALL(n) == 0U ) && ( UNALIGNED(m) == 0U ))
    {
        /* If we get this far, we know that n is large and m is
word-aligned. */
        aligned_addr = (uint32*) m;

        /* Store D into each char sized location in BUFFER so that
                we can set large blocks quickly.  */
        if(LBLOCKSIZE == 4U)
        {
            /* copy to the buffer */
            buffer = (uint32) ( ( d << 8U ) | d );
            buffer = buffer | ( buffer << 16U );
        }
        else
        {
            /* reset the buffer */
            buffer = 0U;

            /* copy to the buffer the char */
            for(i = 0U; i < LBLOCKSIZE; i++)
            {
                buffer = ( buffer << 8U ) | d;
            }
        }

        /* copy the aligned bytes */
        while(n >= LBLOCKSIZE * 4U)
        {
            /* copy the first four byte word */
            *aligned_addr = buffer;
            aligned_addr++;

            /* copy the second four byte word */
            *aligned_addr = buffer;
            aligned_addr++;

            /* copy the third four byte word */
            *aligned_addr = buffer;
            aligned_addr++;

            /* copy the fourth four byte word */
            *aligned_addr = buffer;
            aligned_addr++;

            /* decrement the number of bytes copied */
            n -= (rtems_size) ( 4U * LBLOCKSIZE );
        }

        /* copy the remaining bytes */
        while(n >= LBLOCKSIZE)
        {
            /* copy the first four byte word */
            *aligned_addr = buffer;
            aligned_addr++;

            /* decrement the number of bytes copied */
            n -= LBLOCKSIZE;
        }
        /* Pick up the remainder with a bytewise loop.  */
        s = (sint8*) aligned_addr;
    }

    /* copy the remaining bytes */
    while(n > 0U)
    {
        /* copy the byte */
        *s = (sint8) d;
        s++;
        /* decrement size */
        n--;
    }

    /* return the destination address */
    return m;

#endif /* not PREFER_SIZE_OVER_SPEED */
}





Hope this help ;)
Manuel Coutinho

-----Original Message-----
From: gcc-help-owner@gcc.gnu.org [mailto:gcc-help-owner@gcc.gnu.org] On
Behalf Of Kai Ruottu
Sent: 07 February 2011 14:43
To: gcc-help@gcc.gnu.org
Cc: ali hagigat
Subject: Re: -nostdlib option!

7.2.2011 14:44, ali hagigat kirjoitti:

> How will be memset, memcpy, etc. Can i copy them from the source code
> of gcc? But they are dependent to other functions in other libraries
> probably and some headers.

Most probably these functions are standalone and don't
call other functions... Does your program really call
them? What does 'nm' say anout undefined symbols in the
compiled object(s)?

> Are those functions available stand alone some where?

For instance in :
   newlib-1.18.0/newlib/libc/machine/i386
in the current newlib sources.

Re: -nostdlib option!

[Drasko DRASKOVIC]

I hope that you are not pasting NDA covered SW to this list.

BR,
Drasko

On Mon, Feb 7, 2011 at 5:10 PM, Manuel Coutinho
<manuel.coutinho@edisoft.pt> wrote:
> Yes.
>
> Memset and memcpy are standalone functions. My team (at Edisoft) has a
> version for these files.
>
> For memcpy we have the file:
>
> /**
>  * @brief check if either of the addresses are aligned
>  *
>  * Nonzero if either X or Y is not aligned on a "long" boundary.
>  */
> #define UNALIGNED(X, Y) \
>  (((uint32)X & (sizeof (uint32) - 1U)) | ((uint32)Y & (sizeof (uint32) -
> 1U)))
>
> /**
>  * @brief determine how many bytes are copied each iteration of the 4X
> unrolled
>  * loop
>  */
> #define BIGBLOCKSIZE    ((uint32)sizeof (sint32) << 2U)
>
> /**
>  * @brief determine how many bytes are copied each iteration of the word
> copy
>  * loop
>  */
> #define LITTLEBLOCKSIZE ((uint32)sizeof (sint32))
>
> /**
>  * @brief Threshhold for punting to the byte copier  */ #define
> TOO_SMALL(LEN)  ((LEN) < BIGBLOCKSIZE)
>
>
> void *memcpy(void *dst0 , const void *src0 , rtems_size len0) {
>
> #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
>
>    /* get destination address as a byte pointer */
>    sint8 *dst = (sint8 *) dst0;
>
>    /* get source address as a byte pointer */
>    sint8 *src = (const sint8 *) src0;
>
>
>    /* save the destination address */
>    void * save = dst0;
>
>    /* copy the source vector to destination for len0 bytes*/
>    while(len0--)
>    {
>        /* copy the source to the destination */
>        *dst++ = *src++;
>    }
>
>    /* return the saved destination address */
>    return save;
>
> #else
>
>    /* get destination address as a byte pointer */
>    sint8 *dst = (sint8 *) dst0;
>
>    /* get source address as a byte pointer */
>    const sint8 *src = src0;
>
>    /* alligned destination pointer */
>    sint32 *aligned_dst;
>
>    /* aligned source pointer */
>    const sint32 *aligned_src;
>
>    /* lenght in integer */
>    uint32 len = (uint32) len0;
>
>
>    /* If the size is small, or either SRC or DST is unaligned,
>     * then punt into the byte copy loop.  This should be rare.  */
>    if(( ( TOO_SMALL(len) ) == 0U ) &&
>       ( ( UNALIGNED((uint32) src0 , (uint32) dst0) ) == FALSE ))
>    {
>        /* get the destination */
>        aligned_dst = (sint32*) dst;
>
>        /* get the source */
>        aligned_src = (sint32*) src;
>
>        /* Copy 4X long words at a time if possible.  */
>        while(len >= BIGBLOCKSIZE)
>        {
>            /* copy the first 4 bytes */
>            *aligned_dst = *aligned_src;
>            aligned_dst++;
>            aligned_src++;
>
>            /* copy the second 4 bytes */
>            *aligned_dst = *aligned_src;
>            aligned_dst++;
>            aligned_src++;
>
>            /* copy the third 4 bytes */
>            *aligned_dst = *aligned_src;
>            aligned_dst++;
>            aligned_src++;
>
>            /* copy the fourth 4 bytes */
>            *aligned_dst = *aligned_src;
>            aligned_dst++;
>            aligned_src++;
>
>            /* decrement the number of bytes left to copy */
>            len -= BIGBLOCKSIZE;
>        }
>
>        /* Copy one long word at a time if possible.  */
>        while(len >= LITTLEBLOCKSIZE)
>        {
>            /* copy 4 bytes */
>            *aligned_dst = *aligned_src;
>            aligned_dst++;
>            aligned_src++;
>
>            /* decrement the number of bytes left to copy */
>            len -= LITTLEBLOCKSIZE;
>        }
>
>        /* Pick up any residual with a byte copier.  */
>        dst = (sint8*) aligned_dst;
>        src = (sint8*) aligned_src;
>    }
>
>    /* copy residual bytes (maximum of 3) */
>    while(len > 0U)
>    {
>        /* copy each byte */
>        *dst = *src;
>
>        /* increment the pointer */
>        dst++;
>        src++;
>
>        /* decrement number of bytes */
>        len--;
>    }
>
>    /* return the destination address */
>    return dst0;
>
> #endif /* not PREFER_SIZE_OVER_SPEED */
> }
>
>
>
>
> For the file memset.c we have the file:
>
>
> /**
>  * @brief size of a block
>  */
> #define LBLOCKSIZE ((uint32) sizeof(uintptr))
>
> /**
>  * @brief check if the address is alligned  */ #define UNALIGNED(X)
> ((uintptr)X & (LBLOCKSIZE - 1))
>
> /**
>  * @brief check if the size is too small  */ #define TOO_SMALL(LEN) ((LEN) <
> LBLOCKSIZE)
>
>
> void *memset(void *m , sint32 c , rtems_size n) {
>
> #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
>
>    /* copy the destination address to another variable */
>    sint8 *s = (sint8 *) m;
>
>
>    /* while there are bytes left to copy */
>    while(n != 0)
>    {
>        /* copy the byte */
>        *s = (sint8) c;
>
>        /* increment index on array */
>        s++;
>
>        /* decrement number of remaining bytes to copy */
>        n--;
>    }
>
>    /* return the destination address */
>    return m;
>
> #else
>
>    /* pointer to address where to write */
>    sint8 *s = (sint8 *) m;
>
>    /* iterator */
>    uint32 i;
>
>    /* buffer where to place small array */
>    uint32 buffer;
>
>    /* pointer to address aligned */
>    uintptr *aligned_addr;
>
>    /* To avoid sign extension, copy c to an unsigned variable.  */
>    uint32 d = (uint32) c & 0xffU;
>
>
>    /* check if the size is too small or the destination address in not
> aligned */
>    if(( TOO_SMALL(n) == 0U ) && ( UNALIGNED(m) == 0U ))
>    {
>        /* If we get this far, we know that n is large and m is
> word-aligned. */
>        aligned_addr = (uint32*) m;
>
>        /* Store D into each char sized location in BUFFER so that
>                we can set large blocks quickly.  */
>        if(LBLOCKSIZE == 4U)
>        {
>            /* copy to the buffer */
>            buffer = (uint32) ( ( d << 8U ) | d );
>            buffer = buffer | ( buffer << 16U );
>        }
>        else
>        {
>            /* reset the buffer */
>            buffer = 0U;
>
>            /* copy to the buffer the char */
>            for(i = 0U; i < LBLOCKSIZE; i++)
>            {
>                buffer = ( buffer << 8U ) | d;
>            }
>        }
>
>        /* copy the aligned bytes */
>        while(n >= LBLOCKSIZE * 4U)
>        {
>            /* copy the first four byte word */
>            *aligned_addr = buffer;
>            aligned_addr++;
>
>            /* copy the second four byte word */
>            *aligned_addr = buffer;
>            aligned_addr++;
>
>            /* copy the third four byte word */
>            *aligned_addr = buffer;
>            aligned_addr++;
>
>            /* copy the fourth four byte word */
>            *aligned_addr = buffer;
>            aligned_addr++;
>
>            /* decrement the number of bytes copied */
>            n -= (rtems_size) ( 4U * LBLOCKSIZE );
>        }
>
>        /* copy the remaining bytes */
>        while(n >= LBLOCKSIZE)
>        {
>            /* copy the first four byte word */
>            *aligned_addr = buffer;
>            aligned_addr++;
>
>            /* decrement the number of bytes copied */
>            n -= LBLOCKSIZE;
>        }
>        /* Pick up the remainder with a bytewise loop.  */
>        s = (sint8*) aligned_addr;
>    }
>
>    /* copy the remaining bytes */
>    while(n > 0U)
>    {
>        /* copy the byte */
>        *s = (sint8) d;
>        s++;
>        /* decrement size */
>        n--;
>    }
>
>    /* return the destination address */
>    return m;
>
> #endif /* not PREFER_SIZE_OVER_SPEED */
> }
>
>
>
>
>
> Hope this help ;)
> Manuel Coutinho
>
> -----Original Message-----
> From: gcc-help-owner@gcc.gnu.org [mailto:gcc-help-owner@gcc.gnu.org] On
> Behalf Of Kai Ruottu
> Sent: 07 February 2011 14:43
> To: gcc-help@gcc.gnu.org
> Cc: ali hagigat
> Subject: Re: -nostdlib option!
>
> 7.2.2011 14:44, ali hagigat kirjoitti:
>
>> How will be memset, memcpy, etc. Can i copy them from the source code
>> of gcc? But they are dependent to other functions in other libraries
>> probably and some headers.
>
> Most probably these functions are standalone and don't
> call other functions... Does your program really call
> them? What does 'nm' say anout undefined symbols in the
> compiled object(s)?
>
>> Are those functions available stand alone some where?
>
> For instance in :
>   newlib-1.18.0/newlib/libc/machine/i386
> in the current newlib sources.
>
>
>

RE: -nostdlib option!

[Manuel Coutinho]

Nope ;)

-----Original Message-----
From: Drasko DRASKOVIC [mailto:drasko.draskovic@gmail.com] 
Sent: 07 February 2011 16:21
To: Manuel Coutinho
Cc: Kai Ruottu; gcc-help@gcc.gnu.org; ali hagigat
Subject: Re: -nostdlib option!

I hope that you are not pasting NDA covered SW to this list.

BR,
Drasko

On Mon, Feb 7, 2011 at 5:10 PM, Manuel Coutinho
<manuel.coutinho@edisoft.pt> wrote:
> Yes.
>
> Memset and memcpy are standalone functions. My team (at Edisoft) has a
> version for these files.
>
> For memcpy we have the file:
>
> /**
>  * @brief check if either of the addresses are aligned
>  *
>  * Nonzero if either X or Y is not aligned on a "long" boundary.
>  */
> #define UNALIGNED(X, Y) \
>  (((uint32)X & (sizeof (uint32) - 1U)) | ((uint32)Y & (sizeof (uint32) -
> 1U)))
>
> /**
>  * @brief determine how many bytes are copied each iteration of the 4X
> unrolled
>  * loop
>  */
> #define BIGBLOCKSIZE    ((uint32)sizeof (sint32) << 2U)
>
> /**
>  * @brief determine how many bytes are copied each iteration of the word
> copy
>  * loop
>  */
> #define LITTLEBLOCKSIZE ((uint32)sizeof (sint32))
>
> /**
>  * @brief Threshhold for punting to the byte copier  */ #define
> TOO_SMALL(LEN)  ((LEN) < BIGBLOCKSIZE)
>
>
> void *memcpy(void *dst0 , const void *src0 , rtems_size len0) {
>
> #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
>
>    /* get destination address as a byte pointer */
>    sint8 *dst = (sint8 *) dst0;
>
>    /* get source address as a byte pointer */
>    sint8 *src = (const sint8 *) src0;
>
>
>    /* save the destination address */
>    void * save = dst0;
>
>    /* copy the source vector to destination for len0 bytes*/
>    while(len0--)
>    {
>        /* copy the source to the destination */
>        *dst++ = *src++;
>    }
>
>    /* return the saved destination address */
>    return save;
>
> #else
>
>    /* get destination address as a byte pointer */
>    sint8 *dst = (sint8 *) dst0;
>
>    /* get source address as a byte pointer */
>    const sint8 *src = src0;
>
>    /* alligned destination pointer */
>    sint32 *aligned_dst;
>
>    /* aligned source pointer */
>    const sint32 *aligned_src;
>
>    /* lenght in integer */
>    uint32 len = (uint32) len0;
>
>
>    /* If the size is small, or either SRC or DST is unaligned,
>     * then punt into the byte copy loop.  This should be rare.  */
>    if(( ( TOO_SMALL(len) ) == 0U ) &&
>       ( ( UNALIGNED((uint32) src0 , (uint32) dst0) ) == FALSE ))
>    {
>        /* get the destination */
>        aligned_dst = (sint32*) dst;
>
>        /* get the source */
>        aligned_src = (sint32*) src;
>
>        /* Copy 4X long words at a time if possible.  */
>        while(len >= BIGBLOCKSIZE)
>        {
>            /* copy the first 4 bytes */
>            *aligned_dst = *aligned_src;
>            aligned_dst++;
>            aligned_src++;
>
>            /* copy the second 4 bytes */
>            *aligned_dst = *aligned_src;
>            aligned_dst++;
>            aligned_src++;
>
>            /* copy the third 4 bytes */
>            *aligned_dst = *aligned_src;
>            aligned_dst++;
>            aligned_src++;
>
>            /* copy the fourth 4 bytes */
>            *aligned_dst = *aligned_src;
>            aligned_dst++;
>            aligned_src++;
>
>            /* decrement the number of bytes left to copy */
>            len -= BIGBLOCKSIZE;
>        }
>
>        /* Copy one long word at a time if possible.  */
>        while(len >= LITTLEBLOCKSIZE)
>        {
>            /* copy 4 bytes */
>            *aligned_dst = *aligned_src;
>            aligned_dst++;
>            aligned_src++;
>
>            /* decrement the number of bytes left to copy */
>            len -= LITTLEBLOCKSIZE;
>        }
>
>        /* Pick up any residual with a byte copier.  */
>        dst = (sint8*) aligned_dst;
>        src = (sint8*) aligned_src;
>    }
>
>    /* copy residual bytes (maximum of 3) */
>    while(len > 0U)
>    {
>        /* copy each byte */
>        *dst = *src;
>
>        /* increment the pointer */
>        dst++;
>        src++;
>
>        /* decrement number of bytes */
>        len--;
>    }
>
>    /* return the destination address */
>    return dst0;
>
> #endif /* not PREFER_SIZE_OVER_SPEED */
> }
>
>
>
>
> For the file memset.c we have the file:
>
>
> /**
>  * @brief size of a block
>  */
> #define LBLOCKSIZE ((uint32) sizeof(uintptr))
>
> /**
>  * @brief check if the address is alligned  */ #define UNALIGNED(X)
> ((uintptr)X & (LBLOCKSIZE - 1))
>
> /**
>  * @brief check if the size is too small  */ #define TOO_SMALL(LEN) ((LEN)
<
> LBLOCKSIZE)
>
>
> void *memset(void *m , sint32 c , rtems_size n) {
>
> #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
>
>    /* copy the destination address to another variable */
>    sint8 *s = (sint8 *) m;
>
>
>    /* while there are bytes left to copy */
>    while(n != 0)
>    {
>        /* copy the byte */
>        *s = (sint8) c;
>
>        /* increment index on array */
>        s++;
>
>        /* decrement number of remaining bytes to copy */
>        n--;
>    }
>
>    /* return the destination address */
>    return m;
>
> #else
>
>    /* pointer to address where to write */
>    sint8 *s = (sint8 *) m;
>
>    /* iterator */
>    uint32 i;
>
>    /* buffer where to place small array */
>    uint32 buffer;
>
>    /* pointer to address aligned */
>    uintptr *aligned_addr;
>
>    /* To avoid sign extension, copy c to an unsigned variable.  */
>    uint32 d = (uint32) c & 0xffU;
>
>
>    /* check if the size is too small or the destination address in not
> aligned */
>    if(( TOO_SMALL(n) == 0U ) && ( UNALIGNED(m) == 0U ))
>    {
>        /* If we get this far, we know that n is large and m is
> word-aligned. */
>        aligned_addr = (uint32*) m;
>
>        /* Store D into each char sized location in BUFFER so that
>                we can set large blocks quickly.  */
>        if(LBLOCKSIZE == 4U)
>        {
>            /* copy to the buffer */
>            buffer = (uint32) ( ( d << 8U ) | d );
>            buffer = buffer | ( buffer << 16U );
>        }
>        else
>        {
>            /* reset the buffer */
>            buffer = 0U;
>
>            /* copy to the buffer the char */
>            for(i = 0U; i < LBLOCKSIZE; i++)
>            {
>                buffer = ( buffer << 8U ) | d;
>            }
>        }
>
>        /* copy the aligned bytes */
>        while(n >= LBLOCKSIZE * 4U)
>        {
>            /* copy the first four byte word */
>            *aligned_addr = buffer;
>            aligned_addr++;
>
>            /* copy the second four byte word */
>            *aligned_addr = buffer;
>            aligned_addr++;
>
>            /* copy the third four byte word */
>            *aligned_addr = buffer;
>            aligned_addr++;
>
>            /* copy the fourth four byte word */
>            *aligned_addr = buffer;
>            aligned_addr++;
>
>            /* decrement the number of bytes copied */
>            n -= (rtems_size) ( 4U * LBLOCKSIZE );
>        }
>
>        /* copy the remaining bytes */
>        while(n >= LBLOCKSIZE)
>        {
>            /* copy the first four byte word */
>            *aligned_addr = buffer;
>            aligned_addr++;
>
>            /* decrement the number of bytes copied */
>            n -= LBLOCKSIZE;
>        }
>        /* Pick up the remainder with a bytewise loop.  */
>        s = (sint8*) aligned_addr;
>    }
>
>    /* copy the remaining bytes */
>    while(n > 0U)
>    {
>        /* copy the byte */
>        *s = (sint8) d;
>        s++;
>        /* decrement size */
>        n--;
>    }
>
>    /* return the destination address */
>    return m;
>
> #endif /* not PREFER_SIZE_OVER_SPEED */
> }
>
>
>
>
>
> Hope this help ;)
> Manuel Coutinho
>
> -----Original Message-----
> From: gcc-help-owner@gcc.gnu.org [mailto:gcc-help-owner@gcc.gnu.org] On
> Behalf Of Kai Ruottu
> Sent: 07 February 2011 14:43
> To: gcc-help@gcc.gnu.org
> Cc: ali hagigat
> Subject: Re: -nostdlib option!
>
> 7.2.2011 14:44, ali hagigat kirjoitti:
>
>> How will be memset, memcpy, etc. Can i copy them from the source code
>> of gcc? But they are dependent to other functions in other libraries
>> probably and some headers.
>
> Most probably these functions are standalone and don't
> call other functions... Does your program really call
> them? What does 'nm' say anout undefined symbols in the
> compiled object(s)?
>
>> Are those functions available stand alone some where?
>
> For instance in :
>   newlib-1.18.0/newlib/libc/machine/i386
> in the current newlib sources.
>
>
>

Re: -nostdlib option!

[ali hagigat]

I am compiling my C programs with -nostdlib option without providing
mem functions like memcpy and GNU tool chain has not complained so
far(gcc 4.4.2, Fedora 12). Is that natural? I have defined char
pointers, nested functions and no error so far. I wonder if anybody
can write a simple C program and compile it with -nostdlib so that the
compiler needs one of mem functions and the compiler stops with an
error.


On 2/15/11, Patrick Horgan <phorgan1@yahoo.com> wrote:
> On 02/07/2011 04:44 AM, ali hagigat wrote:
>> Thank you Manuel.
>> How will be memset, memcpy, etc. Can i copy them from the source code
>> of gcc? But they are dependent to other functions in other libraries
>> probably and some headers.
>> Are those functions available stand alone some where?
>>
>>
>> On Mon, Feb 7, 2011 at 2:51 PM, Manuel Coutinho
>>> Hi
>>>
>>> Other mechanism: supply your own memset, memcpy, etc.
>>> If you do this, the linker will know which memset, memcpy, etc to use and
>>> will not complaint about not using libc.
>>>
>>> Regards
>>> Manuel Coutinho
>>>
> you would just write your own copies of these methods.  These are very
> simple functions any beginning computer science student could write in a
> few minutes.  For example:
>
> void *memset(void *s, int c, size_t n)
> {
>      size_t ctr;
>      char *ptr=s;
>      for(ctr=0;ctr<n;ctr++){
>          *(ptr+ctr)=(char)c;
>      }
>      return s;
> }
>
>
>

Re: -nostdlib option!

[Axel Freyn]

Hi Ali,
On Tue, Feb 15, 2011 at 11:06:08AM +0330, ali hagigat wrote:
> I am compiling my C programs with -nostdlib option without providing
> mem functions like memcpy and GNU tool chain has not complained so
> far(gcc 4.4.2, Fedora 12). Is that natural? I have defined char
> pointers, nested functions and no error so far. I wonder if anybody
> can write a simple C program and compile it with -nostdlib so that the
> compiler needs one of mem functions and the compiler stops with an
> error.
try the program:
int main(){
  char *c = (char*) malloc(10*sizeof(char));
  free(c);
}
On my machine (gcc-4.3.2), this compiles fine without the switch (just
warning about the missing header file):
~> gcc nostdlib.c
nostdlib.c: In function ‘main’:
nostdlib.c:2: warning: incompatible implicit declaration of built-in function ‘malloc’

and with "-nostdlib", it gives the link error as expected:
~> gcc -nostdlib nostdlib.c
nano-th2 ~ $ gcc -nostdlib nostdlib.c
nostdlib.c: In function ‘main’:
nostdlib.c:2: warning: incompatible implicit declaration of built-in function ‘malloc’
nostdlib.c:3: warning: incompatible implicit declaration of built-in function ‘free’
/usr/bin/ld: warning: cannot find entry symbol _start; defaulting to 00000000004000e8
/tmp/cckDrpxw.o: In function `main':
nostdlib.c:(.text+0xe): undefined reference to `malloc'
nostdlib.c:(.text+0x1b): undefined reference to `free'
collect2: ld returned 1 exit status

Adding "#include <stdlib.h>" does not solve the problem, just removes
the warning.

Axel

> 
> 
> On 2/15/11, Patrick Horgan <phorgan1@yahoo.com> wrote:
> > On 02/07/2011 04:44 AM, ali hagigat wrote:
> >> Thank you Manuel.
> >> How will be memset, memcpy, etc. Can i copy them from the source code
> >> of gcc? But they are dependent to other functions in other libraries
> >> probably and some headers.
> >> Are those functions available stand alone some where?
> >>
> >>
> >> On Mon, Feb 7, 2011 at 2:51 PM, Manuel Coutinho
> >>> Hi
> >>>
> >>> Other mechanism: supply your own memset, memcpy, etc.
> >>> If you do this, the linker will know which memset, memcpy, etc to use and
> >>> will not complaint about not using libc.
> >>>
> >>> Regards
> >>> Manuel Coutinho
> >>>
> > you would just write your own copies of these methods.  These are very
> > simple functions any beginning computer science student could write in a
> > few minutes.  For example:
> >
> > void *memset(void *s, int c, size_t n)
> > {
> >      size_t ctr;
> >      char *ptr=s;
> >      for(ctr=0;ctr<n;ctr++){
> >          *(ptr+ctr)=(char)c;
> >      }
> >      return s;
> > }
> >
> >
> >

Re: -nostdlib option!

[Jonathan Wakely]

On 15 February 2011 09:50, Axel Freyn wrote:
> Hi Ali,
> On Tue, Feb 15, 2011 at 11:06:08AM +0330, ali hagigat wrote:
>> I am compiling my C programs with -nostdlib option without providing
>> mem functions like memcpy and GNU tool chain has not complained so
>> far(gcc 4.4.2, Fedora 12). Is that natural? I have defined char
>> pointers, nested functions and no error so far. I wonder if anybody
>> can write a simple C program and compile it with -nostdlib so that the
>> compiler needs one of mem functions and the compiler stops with an
>> error.
> try the program:
> int main(){
>  char *c = (char*) malloc(10*sizeof(char));
>  free(c);
> }
> On my machine (gcc-4.3.2), this compiles fine without the switch (just
> warning about the missing header file):
> ~> gcc nostdlib.c
> nostdlib.c: In function ‘main’:
> nostdlib.c:2: warning: incompatible implicit declaration of built-in function ‘malloc’
>
> and with "-nostdlib", it gives the link error as expected:

I think you've missed the point - obviously if you call a stdlib
function it will be required.

Ali is asking about the case where the compiler generates calls to
stdlib functions which do not appear explicitly in the code. See the
docs for -nostdlib in the manual.

       -nostdlib
           Do not use the standard system startup files or libraries when
           linking.  No startup files and only the libraries you specify will
           be passed to the linker.  The compiler may generate calls to "mem-
           cmp", "memset", "memcpy" and "memmove".  These entries are usually
           resolved by entries in libc.  These entry points should be supplied
           through some other mechanism when this option is specified.

Re: -nostdlib option!

[Axel Freyn]

On Tue, Feb 15, 2011 at 10:28:30AM +0000, Jonathan Wakely wrote:
> On 15 February 2011 09:50, Axel Freyn wrote:
> 
> I think you've missed the point - obviously if you call a stdlib
> function it will be required.
> 
> Ali is asking about the case where the compiler generates calls to
> stdlib functions which do not appear explicitly in the code. See the
> docs for -nostdlib in the manual.
I see -- sorry for the noise :-)

Axel

Re: -nostdlib option!

[Thomas Martitz]

Am 15.02.2011 08:36, schrieb ali hagigat:
>   I wonder if anybody
> can write a simple C program and compile it with -nostdlib so that the
> compiler needs one of mem functions and the compiler stops with an
> error.


Try struct assigments (e.g. struct foo bar = baz). Perhaps if they're 
big enough gcc doesn't inline the implicit memcpy anymore.

Best regards.

Re: -nostdlib option!

[Ian Lance Taylor]

ali hagigat <hagigatali@gmail.com> writes:

> I am compiling my C programs with -nostdlib option without providing
> mem functions like memcpy and GNU tool chain has not complained so
> far(gcc 4.4.2, Fedora 12). Is that natural? I have defined char
> pointers, nested functions and no error so far. I wonder if anybody
> can write a simple C program and compile it with -nostdlib so that the
> compiler needs one of mem functions and the compiler stops with an
> error.

If I compile this file:

struct s { char a[100000]; };
struct s v;
void f(struct s *p) { v = *p; }

for the x86_64 with no optimization, I get a call to memcpy.

Ian