alt_remap_uncached.c

nios中自定义指令集实现三角函数的软件部分。

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#include "sys/alt_cache.h"
#include "system.h"

#ifdef NIOS2_MMU_PRESENT
/* Convert KERNEL region address to IO region address */
#define BYPASS_DCACHE_MASK   (0x1 << 29)
#else
/* Set bit 31 of address to bypass D-cache */
#define BYPASS_DCACHE_MASK   (0x1 << 31)
#endif

/*
 * Convert a pointer to a block of cached memory, into a block of
 * uncached memory.
 */

volatile void* alt_remap_uncached (void* ptr, alt_u32 len)
{
  alt_dcache_flush (ptr, len);
  return (volatile void*) (((alt_u32) ptr) | BYPASS_DCACHE_MASK);
}