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Altera_Forum's avatar
Altera_Forum
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20 years ago

Does alt_dcache_flush_all() work right?

Hi:

I want to flush all dcache of niosII/f core, I find a function in kitsv1.1\nios2\components\altera_nios2\HAL\src\alt_dcache_flush_all.c , but I wonder if it is correct. the function is like that:

/*

* alt_dcache_flush_all() is called to flush the entire data cache.

*/

void alt_dcache_flush_all (void)

{# if NIOS2_DCACHE_SIZE > 0

alt_dcache_flush (0, NIOS2_DCACHE_SIZE);# endif

}

I read the src of function alt_dcache_flush (void* start, alt_u32 len) in alt_dcache_flush.c. the first param is an address second is a size. we can invoke it like that alt_dcache_flush(&iVal , sizeof(iVal) ), but what does it mean to pass a zero to it as first param just like alt_dcache_flush_all() does? Is it correct?

I am anxious to know the answer. Who can give me some advice? http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/sad.gif

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    Yes, this is correct.

    The Nios II FLUSHD instruction ignores the tag portion of the memory address (the top bits).

    This means that a FLUSHD to address 0x0000 is the same as a FLUSHD to address 0x1000, 0x2000, 0x3000, etc. for a 4096 byte D-cache.

    +james+
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    I got it!thanks !

    I may have read the describtion of flushd and initd instruction, but I ignore the sentence"Ignore the tag,flushd identifies the cache line associated with the computed effective address". because I don&#39;t know what the tag refer to.

    thanks again. http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif