/hw/xfree86/os-support/misc/SlowBcopy.c

/*******************************************************************************
  for Alpha Linux
*******************************************************************************/
 
/* 
 *   Create a dependency that should be immune from the effect of register
 *   renaming as is commonly seen in superscalar processors.  This should
 *   insert a minimum of 100-ns delays between reads/writes at clock rates
 *   up to 100 MHz---GGL
 *   
 *   Slowbcopy(char *src, char *dst, int count)   
 *   
 */ 

#ifdef HAVE_XORG_CONFIG_H
#include <xorg-config.h>
#endif

#include <X11/X.h>
#include "xf86.h"
#include "xf86Priv.h"
#include "xf86_OSlib.h"
#include "compiler.h"

static int really_slow_bcopy;

void
xf86SetReallySlowBcopy(void)
{
	really_slow_bcopy = 1;
}

#if defined(__i386__) || defined(__amd64__)
static void xf86_really_slow_bcopy(unsigned char *src, unsigned char *dst, int len)
{
    while(len--)
    {
	*dst++ = *src++;
	outb(0x80, 0x00);
    }
}
#endif

/* The outb() isn't needed on my machine, but who knows ... -- ost */
void
xf86SlowBcopy(unsigned char *src, unsigned char *dst, int len)
{
#if defined(__i386__) || defined(__amd64__)
    if (really_slow_bcopy) {
	xf86_really_slow_bcopy(src, dst, len);
	return;
    }
#endif
    while(len--)
	*dst++ = *src++;
}

#ifdef __alpha__

#ifdef linux

unsigned long _bus_base(void);

#define useSparse() (!_bus_base())

#define SPARSE (7)

#else

#define useSparse() 0

#define SPARSE 0

#endif

void
xf86SlowBCopyFromBus(unsigned char *src, unsigned char *dst, int count)
{
	if (useSparse())
	{
		unsigned long addr;
		long result;

		addr = (unsigned long) src;
		while (count) {
			result = *(volatile int *) addr;
			result >>= ((addr>>SPARSE) & 3) * 8;
			*dst++ = (unsigned char) (0xffUL & result);
			addr += 1<<SPARSE;
			count--;
			outb(0x80, 0x00);
		}
	}
	else
		xf86SlowBcopy(src, dst, count);
}

void
xf86SlowBCopyToBus(unsigned char *src, unsigned char *dst, int count)
{
	if (useSparse())
	{
		unsigned long addr;

		addr = (unsigned long) dst;
		while (count) {
			*(volatile unsigned int *) addr = (unsigned short)(*src) * 0x01010101;
			src++;
			addr += 1<<SPARSE;
			count--;
			outb(0x80, 0x00);
		}
	}
	else
		xf86SlowBcopy(src, dst, count);
}
#endif